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The upper Silurian(?) to Lower Devonian (Lochkovian) Clam Bank Formation is the most northerly exposed middle Paleozoic foreland-basin succession in the Appalachian orogen. Understanding of its sedimentary history is poor, and there are contradictory interpretations of placement of its lower structural boundary. Our study redefines the lithostratigraphy and subdivides the ~600 m thick formation into three paleoenvironmental successions: a lower coastal plain setting with fluvial channels giving way upsection to coastal flats with carbonate, colluvium with reworked paleosol material, and aeolian (silt) deposits; a middle coastal zone succession following marine transgression and deposition of shoreface sandstone; and an upper alluvial succession host to pedogenic and groundwater calcretes. A basal disconformity, though not exposed, is inferred from lithic and geochemical evidence for sediment mixing with underlying Upper Ordovician sources in the lowermost part of the formation. This supports previous interpretations of Silurian uplift along the Laurentian margin in response to the Salinian orogeny. Sedimentary provenance indicates quartzo-feldspathic sources throughout the formation, and sediment-transport indicators identify a northeast-southwest-oriented basin with northwest-directed fluvial input. U-Pb detrital zircon distributions associated with the paleocolluvium and younger transgressive sandstone document upsection loss of prominent age peaks of late Grenville (~0.98 Ga) and pre-Grenville (1.5, 1.65, and 1.75 Ga) sources. The coastal plain succession and related detrital-zircon signature imply a mixture of distal and proximal sediment sources, the latter related to erosion of a weathered upland and exhumed Precambrian inliers in western Newfoundland. A more regional provenance signature with marine transgression suggests sediment transport in response to Acadian orogenesis. Key words: Clam Bank Formation, sedimentary provenance, U-Pb detrital zircon, Middle Paleozoic, foreland basin, Canadian Appalachians, Introduction The late Silurian (Pridoli) through Early Devonian (Lochkovian) was an interval of significant global change that included onset of Pangaea assembly (Ziegler 1988), pC[O.sub.2] drawdown and global cooling (Chen [...]

Lac Simard is a glaciated Shield basin situated in the Western Quebec Seismic Zone, an area of recurrent intraplate seismicity encompassing several densely populated areas. Previous works nearby have demonstrated that sediments preserved in lake basins hold the potential to serve as valuable archives of paleoseismicity. Correspondingly, a high-resolution chirp seismic reflection survey was conducted in Lac Simard, with results showing four acoustic facies (Af-1 to Af-4) within two stratigraphic successions (SS-1 and SS-2). The lowermost SS-1 is dominated by high-amplitude, laminated Af-2, interpreted as lateglacial varves deposited by suspension from primarily overflows and interflows during glacial lake ponding following deglaciation. Suspension deposition of Af-2 was episodically interrupted by stacked, chaotically bedded, weakly graded to opaque, channelled Af-3 interpreted as either debris flows or high-density turbidity currents. Presence of silt-clast breccias in Af-3 also suggests downslope collapse and reworking of varves from basin sidewalls. The overlying SS-2 is dominated by weakly reflective, laminated, high-frequency varved Af-4, suggesting a continuing seasonal control on postglacial sedimentation but with relative sediment starvation. A basin-wide erosional unconformity separating SS-1 and postglacial SS-2 records the abrupt drainage of glacial Lake Barlow-Ojibway around 8 000 years ago. Considering the history of lake floor disturbance in the region, mass flow facies Af-3 may be seismogenic, and thus, have regional tectonic significance. However, we cannot rule out the possibility of mass flows triggered by abrupt inflows of meltwater and sediment from a highly dynamic retreating Laurentide Ice Sheet prone to surging. Key words: large glacial lakes, glacial sedimentation, seismic reflection stratigraphy, Western Quebec Seismic Zone, 1 Introduction Eastern North America experiences recurrent intraplate earthquakes that are still inadequately understood, particularly with regard to their origin, frequency, and magnitude (e.g., Basham and Adams 1989; Mazzotti 2007; [...]

The Cumberland Basin is one of several sedimentary basins composing the late Paleozoic Maritimes Basin complex of eastern Canada. Pennsylvanian salt tectonics in the Cumberland Basin caused two salt mini-basins to evolve on either side of the Minudie Anticline, a salt wall. South of the wall (Athol Syncline), along the Joggins World Heritage shoreline, an--3000 m succession of strata (Little River, Joggins, Springhill Mines, and Ragged Reef formations) accumulated conformably on the Boss Point Formation. North of the wall (Black Point sub-basin), the biostratigraphically equivalent, but mostly unstudied,--600 m thick succession of Grande Anse Formation lies in angular unconformity on folded and faulted Boss Point and basal Little River formations. Grande Anse Formation sedimentology indicates four lithofacies associations: floodplain (LA1), braided channel (LA2), sheet flood (LA3), and debris flow deposits (LA4). One possible model has the Black Point sub-basin with its own hydrological system, completely separated from the Athol Syncline. A low subsidence rate combined with the low sedimentation rate produced the--600 m thick sand- and mud-prone succession that was contemporaneous with the--3 km succession to the south. The second model proposes that north of the salt wall was exposed to erosion during accumulation of Joggins and Springhill Mines formation strata to the south. Subsequently, the sediment of the lithologically similar Ragged Reef and Grande Anse formations either (i) onlapped to the north, unconformably on the folded Boss Point; or (ii) unconformably-disconformably on the underlying strata after a period of time indistinguishable in the biostratigraphic record. Key words: Grande Anse Formation, Joggins, salt tectonics, stratigraphy, sedimentology. Le bassin de Cumberland estun des bassins sedimentaires qui composent le complexe tardi-paleozoique de bassins des Maritimes, dans l'est du Canada. Une tectonique salifere au Pennsylvanien dans le bassin de Cumberland a entraine la formation de deux mini-bassins de sel de part et d'autre de l'anticlinal de Minudie, un mur de sel. Au sud du mur (synclinal dAthol), le long du littoral du Patrimoine mondial de Joggins, une sequence de quelque 3000 m de strates (Formations de Little River, Joggins, Springhill Mines et Ragged Reef) s'est accumulee de maniere concordante sur la Formation de Boss Point. Au nord du mur (sous-bassin de Black Point), la sequence equivalente du point de vue biostratigraphique, mais generalement non etudiee, de --600 m de la Formation de Grande Anse repose en discordance angulaire sur des roches plissees et faillees de la Formation de Boss Point et de la base de la Formation de Little River. La sedimentologie de la Formation de Grande Anse indique quatre associations de lithofacies, a savoir, des depots de plaines inondables (LA1), de chenaux anastomoses (LA2), d'inondations en nappe (LA3) et de coulees de debris (LA4). Dans un modele possible, le sous-bassin de Black Point et son reseau hydrologique sont completement separes du synclinal dAthol. Une faible vitesse de subsidence combinee a un faible taux de sedimentation a produit la sequence de--600 m riche en sable et en boue contemporaine de la sequence de--3 km situee au sud. Le deuxieme modele propose que le nord du mur de sel ait ete expose a l'erosion durant l'accumulation de strates des Formations de Joggins et Springhill Mines au sud. Par la suite, les sediments des Formations de Ragged Reef et de Grande Anse, semblables sur le plan lithologique, ont soit (i) ete deposes en discordance sur les roches plissees de la Formation de Boss Point, qu'elles ont debordees vers le nord ou (ii) ont ete deposes en discordance sur les strates sous-jacentes apres un intervalle de temps indistinguable dans le profil biostratigraphie. [Traduit par la Redaction] Mots-cles: Formation de Grande Anse, Joggins, tectonique salifere, stratigraphie, sedimentologie., Introduction This paper provides the first detailed study of the Grande Anse Formation through the logging of its three main coastal outcrop localities on both sides of the New Brunswick-Nova [...]

Analyses of marine and terrestrial palynomorphs of Ocean Drilling Program (ODP) Site 645 in Baffin Bay led us to define a new biostratigraphical scheme covering the late Miocene to Pleistocene based on dinocyst and acritarch assemblages. Four biozones were defined. The first one, from 438.6 m below sea floor (mbsf) to 388 mbsf, can be assigned a late Miocene to early Pliocene age (>4.5 Ma), based on the common occurrence of Cristadinium diminutivum and Selenopemphix brevispinosa. Biozone 2, spanning from an erosional unconformity to a recovery hiatus, is marked by the highest occurrences (HOs) of Veriplicidiumfranklinii and Cristadinium diminutivum, which suggest an early Pliocene age >3.6 Ma (~4.5 to ~3.6 Ma). Biozone 3, above the recovery hiatus and up to 220.94 mbsf, corresponds to a late Pliocene or early Pleistocene age based on occurrences of Bitectatodinium readwaldii, Cymatiosphaera? icenorum, and Lavradosphaera canalis. Finally, between 266.4 and 120.56 mbsf, Biozone 4, marked by the HO of Filisphaera filifera, Filisphaera microornata, and Habibacysta tectata, has an early Pleistocene age (>1.4 Ma). Our biostratigraphy implies that horizon bl of the Baffin Bay seismic stratigraphy corresponds to the recovery hiatus at ODP Site 645, which suggests a very thick Pliocene sequence along the Baffin Island slope. Dinocyst assemblages and terrestrial palynomorphs in our records indicate that the late Miocene and (or) early Pliocene were characterized by relatively warm coastal surface waters and boreal forest or forested tundra vegetation over adjacent lands. In contrast, the early Pleistocene dinocyst assemblages above the recovery hiatus indicate cold surface waters, while pollen data suggest reduced vegetation cover on adjacent lands. Key words: Baffin Bay, dinocysts, biostratigraphy, Pliocene, Pleistocene, palynology. Des analyses de palynomorphes marins et terrestres provenant du site 645 de l'ODP dans la baie de Baffin nous ont amene a definir un nouveau schema biostratigraphique couvrant la periode du Miocene superieur au Pleistocene, a la lumiere d'assemblages de dinokystes et d'acritarches. Quatre biozones ont ete definies. La premiere, qui couvre de 438,6 m sous le fond marin (msfm) a 388 msfm, peut se voir attribuer un age miocene superieur a pliocene inferieur (>4,5 Ma), a la lumiere de la presence repandue de Cristadinium diminutivum et de Selenopemphix brevispinosa. La biozone 2, qui recouvre une discordance d'erosion et un hiatus dans la sequence sedimentaire carottee, est marquee par les occurrence superieures (OS) de Veriplicidium franklinii et de Cristadinium diminutivum, qui indiqueraient un age pliocene inferieur de >3,6 Ma (~4,5 Ma a ~3,6 Ma). La biozone 3, qui couvre du hiatus de recuperation jusqu'a 220,94 msfm, correspond a un age pliocene superieur ou pleistocene infereur a la lumiere de la presence de Bitectatodinium readwaldii, Cymatiosphaera? icenorum et Lavradosphaera canalis. Enfin, de 266,4 msfm a 120,56 msfm, la biozone 4, marquee par les OS de Filisphaera filifera, Filisphaera microornata et Habibacysta tectata, est d'age pleistocene inferieur (>1,4 Ma). Notre biostratigraphie implique que l'horizon bl de la stratig-raphie sismique de la baie de Baffin correspond au hiatus de recuperation au site 645 de l'ODP, ce qui indiquerait la presence d'une sequence pliocene tres epaisse le long du talus de la terre de Baffin. Les assemblages de dinokystes et de palynomorphes terrestres dans les sediments analyses indiquent que le Miocene superieur et/ou le Pliocene inferieur etaient caracterises par des eaux de surface littorales relativement chaudes et une vegetation de foret boreale ou de toundra arboree sur les terres adjacentes. En comparaison, les assemblages de dinokystes d'age pleistocene inferieur au-dessus du hiatus indiquent des eaux de surface froides et que les donnees polliniques indiqueraient une couverture vegetale reduite sur les terres adjacentes. [Traduit par la Redaction] Mots-cles: baie de Baffin, dinokystes, biostratigraphie, Pliocene, Pleistocene, palynologie., Introduction Baffin Bay is an important transitional basin for heat and salt exchanges between the Arctic and North Atlantic oceans (Fig. 1); it receives more than one-third of the freshwater [...]

The Maritimes Basin of Atlantic Canada contains a rich record of Pennsylvanian cyclothems. Previous studies have focused on rapidly subsiding depocenters in the central part of the basin where Carboniferous successions feature cyclic alternations between terrestrial and marginal marine strata. In contrast, the Pennsylvanian Clifton Formation was deposited on the relatively stable New Brunswick platform and contains almost entirely terrestrial strata. Although early studies of the Clifton Formation noted a cyclic architecture, particularly within Member B, this unit has remained understudied. We provide a sedimentological and sequence stratigraphic framework for the lower 85 m of Member B and interpret our results relative to a broader regional framework. Near the base of the study interval, the highstand systems tract is composed of red floodplain mudrocks; overlying sequence boundaries are composed of calcretes and (or) channels. The transgressive systems tract and maximumflooding surface are representedby coals and aquatic bivalve-bearing mudrocks. Moving upward through the section, the architecture of the highstand systems tract remains largely unchanged while sequence-bounding paleosols become less well developed, the transgressive systems tract becomes thinner and eventually not preserved, and the maximum flooding surface is only occasionally preserved, possibly represented by carbonaceous shales. These changes in cyclic architecture may be attributed to changes in the magnitude of glacioeustatic fluctuations, climate, and (or) the accommodation/sediment supply ratio. The results of this study show that the Clifton Formation represents the terrestrial/proximal endmember for cyclicity in the Maritimes Basin and provide new insight into paleotopography as a possible control on cyclothem architecture. Key words: sequence stratigraphy, sedimentology, cyclicity, Clifton Formation, Maritimes Basin. Le bassin des Maritimes du Canada atlantique contient un riche registre de cyclothèmes pennsylvaniens. Les études antérieures se sont concentrées sur des centres de dépôt à subsidence rapide dans la partie centrale du bassin, où des successions carbonifères présentent des alternances cycliques de strates terrestres et de la marge océanique. En revanche, la Formation pennsylvanienne de Clifton a été déposée sur la plateforme relativement stable du Nouveau-Brunswick et est composée presque exclusivement de strates terrestres. Bien que des études antérieures de la Formation de Clifton aient noté une architecture cyclique, particulièrement dans son membre B, cette unité demeure sous-étudiée. Nous présentons un cadre sédimentologique et de stratigraphie séquentielle pour les 85 m inférieurs du membre B et interprétons nos résultats par rapport à un cadre régional plus large. Près de la base de l'intervalle étudié, un cortège de haut niveau est composé de mudrocks rouges de plaine inondable; les limites de séquence sus-jacentes sont composées de calcrètes ou de dépôts de chenaux. Le cortège transgressif et la surface d'inondation maximale sont représentés par des charbons et des mudrocks à bivalves aquatiques. Plus haut dans la coupe, l'architecture du cortège de haut niveau demeure largement inchangée, alors que les paléosols définissant des limites de séquence deviennent moins bien développés, le cortège transgressif devient plus mince, jusqu'à n'être plus préservé, et la surface d'inondation maximale n'est qu'occasionnellement préservée et possiblement représentée par des schistes charbonneux. Ces variations de l'architecture cyclique peuvent être attribuées à des variations de la magnitude des fluctuations glacioeustatiques, du climat ou du rapport entre l'espace disponible et l'apport de sédiments. Les résultats de l'étude montrent que la Formation de Clifton représente le membre de l'extrémité terrestre/proximale en ce qui concerne la cyclicité dans le bassin des Maritimeset fournit de nouveaux renseignements sur la paléotopographie comme contrôle possible de l'architecture des cyclothèmes. [Traduit par la Rédaction] Mots-clés : stratigraphie séquentielle, sédimentologie, cyclicité, Formation de Clifton, bassin des Maritimes., Introduction Cyclothems are cyclic, often coal-bearing successions of marine and (or) terrestrial strata typical of late Paleozoic sedimentary basins (e.g., Udden 1912; Wanless and Shepard 1936; Heckel et al. 1998). [...]

Abstract: Modern processing methods were applied to 3400 line-kilometres of legacy seismic data from Sabine Peninsula of Melville Island in the Canadian Arctic Islands. Post-stack reprocessing improved the imaging, allowing [...]

This study investigates the Quaternary stratigraphy of the north Okanagan Valley to inform hydrogeological studies. The north Okanagan Valley extends from the north end of Okanagan Lake to Enderby in the southern interior of British Columbia, Canada. Prior surficial geology mapping, provincial and private borehole data, historical seismic profiling, and a new 5 km high-resolution seismic reflection profile were examined to characterize up to 580 m thickness of unconsolidated sediments. A mixture of glacial and interglacial sediments of uncertain Pleistocene age infills bedrock lows that extend below sea level. These are unconformably overlain by a sand and gravel unit of at least Early Wisconsin age (>65 000 years BP). It is in turn unconformably onlapped by nonglacial, organic-rich, lacustrine and alluvial deposits of Middle Wisconsin age (65 000-23 000 years BP). This unit was eroded and overlain by a fine sand to silty sand unit deposited immediately prior to, or during, the Fraser Glaciation advance (>23 000 years BP). Diamict and glacial deposits including valley-side kame overlie these sands at some of the valley margins. Glaciolacustrine sediments of the end of the Fraser Glaciation have no appreciable organic matter and overlie the fine sands in the main Okanagan Valley; these form the majority of the surface outcrop. Recessional glaciodeltaic sediments overlie, and in some places may interfinger with, these glaciolacustrine sediments, which indicates an open proglacial lake environment during late glacial stages. These materials and fan-shaped periglacial debris flow deposits are incised by late Holocene fluvial downcutting. The north Okanagan Valley stratigraphy preserves the record of several glacial and interglacial periods, which suggests that overdeepening of the bedrock surface of the Okanagan Valley may be older than previously suggested. La presente etude analyse la stratigraphie du Quaternaire du nord de la vallee de l'Okanagan dans le but d'obtenir des donnees pour des etudes hydrogeologiques. Le nord de la vallee de l'Okanagan s'etend de l'extremite nord du lac kanagan jusqu';! Enderby dans le sud interieur de la Colombie-Britannique, Canada. Une cartographie anterieure de la geologie de surface, des donnees provinciales et privees de de forages, des profils sismiques historiques et un nouveau profil sismique reflexion a haute resolution, d'une longueur de 5 km, ont ete examines dans le but de caracteriser des sediments non consolides atteignant une epaisseur de 580 m. Un melange de sediments glaciaires et interglaciaires, d'age Pleistocene incertain, remplit des creux du socle qui s'etendent sous le niveau de la mer. Une unite de sable et de gravier, d'age au moins Wisconsin precoce (>65 000 annees avant le present), repose de facon discordante sur ces sediments. Des depots lacustres et alluviaux, riches en matiere organique, datant du Wisconsin moyen (65 000-23 000 annees avant le present), recouvrent a leur tour et de maniere discordante transgressive l'unite de sable. Cette derniere unite a ete erodee et recouverte d'une unite de sable fin a silteux deposee immediatement avant, ou durant, l'avancee glaciaire Fraser (>23 000 annees avant le present). Des depots glaciaires et de diamictons, incluant des kames, recouvrent ces sables a certains endroits sur le bord de la vallee. Les sediments glacio-lacustres de la fin de la glaciation Fraser ne contiennent pas de matiere organique en quantite appreciable et ils recouvrent les sables fins de la vallee principale de l'Okanagan; ces sediments forment la plus grande partie des affleurements en surface. Des sediments glacio-deltaiques de recession recouvrent et parfois se melent a ces sediments glacio-lacustres, indiquant un environnement de lac proglaciaire ouvert durant les derniers stades glaciaires. Ces materiaux et les debris d'ecoulement periglaciaire en forme d'eventail ont ete recoupes par une erosion fluviale verticale a l'Holocene tardif.La stratigraphie du nord de la vallee de l'Okanagan preserve le profil de plusieurs periodes glaciaires et interglaciaires, ce qui suggere que l'incision de la surface du socle de la vallee de l'Okanagan pourrait etre plus ancienne que suggere anterieurement. [Traduit par la Redaction], Introduction The Okanagan Basin is an 8000 [km.sup.2] watershed located in the interior of southern British Columbia, Canada (Fig. 1). Its dominant feature is the 1-4 km wide, north-south trending, [...]

The Wadi Qutabah layered mafic intrusion in northwestern Yemen, considered part of a giant (> 250 [km.sup.2]), Neoproterozoic (~638.5 Ma) intrusion referred to as the Suwar--Wadi Qutabah Complex, has significant potential for economic platinum-group element and Ni-Cu-Co mineralization. A search for platinum-group element mineralization at Wadi Qutabah yielded cores from 14 drillholes along two east and west lines. Stratigraphically, they reveal ~500 m of interlayered norites with subordinate gabbros, anorthosites, pyroxenites, and massive sulphide layers showing modal and cryptic layering that can be correlated between individual holes and between the east and west areas. Energy dispersive spectrometry major element analyses on mineral phases show gradual upward changes in plagioclase composition from An52 (lowest level drilled) to An44, and En61 to En57 in orthopyroxene, up to a distinctive, ilmenite-rich unit termed 5a (augite norite). Above 5a, minerals show a dramatic shift to more primitive An57 and En69 compositions. The gradual changes are typical of layered mafic intrusions and reflect progressive crystallization of magma upward. The dramatic changes, such as above 5a, are also common and reflect magma chamber recharge. In addition to the 500 m reported here, mineral exploration data from more-mafic rocks at Suwar suggest 400 m of layered rocks below those at Wadi Qutabah (total 900 m). A regression analysis plot of the cumulus mineral (plagioclase and orthopyroxene) compositional change versus thickness for seven well-known, giant, layered mafic intrusions suggests that the Suwar--Wadi Qutabah Complex is > 2 km thick and one of the largest (thickness and area) intrusions on Earth. Comparison of the stratigraphy and mineral compositions at Wadi Qutabah with intrusions bearing PGE deposits suggests prospective areas for mineral exploration to the north and south of the study area. Recent reviews identify many similar-aged, mafic-ultramafic intrusive complexes across the Arabian-Nubian Shield. The large size of the Suwar--Wadi Qutabah Complex, its noritic composition, and subcontinental lithospheric mantle signature are characteristics typical of mafic rocks formed in extensionrelated, continental rift settings. Thus, the Suwar--Wadi Qutabah Complex may be part of a previously unrecognized large igneous province associated with a late Proterozoic magmatic event and preserved in what is today, the Arabian Shield. L'intrusion mafique stratifiee de Wadi Qutabah dans le nord-ouest du Yemen, consideree comme faisant partie d'une gigantesque (> 250 [km.sup.2]) intrusion datant du Neoproterozoique (~638,5 Ma) nommee le complexe de Suwar-Wadi Qutabah, aun potentiel significatif de mineralisation en elements du groupe du platine et en Ni-Cu-Co. Une recherche pour une mineralisation en elements du groupe du platine a Wadi Qutabah a fourni des carottes de 14 trous de forage le longde deuxlignes est-ouest. La stratigraphie est composee d'environ 500 m de norites interstratifiees avec, en accessoire, des gabbros, des anorthosites, des pyroxenites et des couches de sulfures massifs montrant une stratification modale et cryptique qui peut etre correlee entre les forages individuels et entre les secteurs est et ouest. Des analyses des elements majeurs par radio-spectrometrie a dissipation d'energie sur les phases minerales montrent des changements graduels augmentant dans la composition des plagioclases, de An52 (plus bas niveau fore) a An44 et de En61 a En57 dans l'orthopyroxene, jusqu'a une unite distincte, nommee 5a (norite a augite), riche en ilmenite. Au-dessus de l'unite 5a, les mineraux montrent un decalage remarquable vers des compositions plus primitives, soit An57 et En69. Les changements graduels sont typiques d'intrusions mafiques stratifiees et ils sont le reflet d'une cristallisation progressive du magma. Les changements importants, tels que ceux au-dessus de 5a, sont aussi frequents et sont le reflet d'une recharge de la chambre magmatique. En plus des 500 m rapportes dans le present article, les donnees d'explorations minerales de roches plus mafiques a Suwar suggerent 400 m de roches stratifiees en-dessous de celles a Wadi Qutabah (pour un total de 900 m). Selon une representation graphique d'une analyse de regression du changement de composition des mineraux de la phase cumulus (plagioclase et orthopyroxene) par rapport a l'epaisseur de sept intrusions gigantesques stratifiees mafiques bien connues, le complexe de Suwar--Wadi Qutabah a une epaisseur superieure a 2 km et il constitue l'une des plus grandes intrusions (en termes d'epaisseur et de superficie) sur la Terre. Une comparaison de la stratigraphie et des compositions minerales a Wadi Qutabah avec des intrusions comportant des gisements d'elements du groupe du platine suggere des endroits potentiels pour l'exploration minerale au nord et au sud du secteur a l'etude. De recents reexamens ont identifie de nombreux complexes d'intrusions mafiques-ultramafiques d'age similaire a travers le Bouclier Arabie-Nubie. La grande taille du complexe de Suwar--Wadi Qutabah, sa composition noritique et sa signature lithospherique sous continentale sont des caracteristiques typiques des roches mafiques formees dans un environnement continental de rift relie a l'extension. Ainsi, le complexe de Suwar Wadi Qutabah pourrait faire partie d'une vaste province ignee, anterieurement inconnue, associee a un evenement magmatique datant du Proterozoique tardif et preservee dans ce qui est aujourd'hui le Bouclier Arabie. [Traduit par la Redaction], Introduction Large layered mafic intrusions are rare discoveries. The Wadi Qutabah and Suwar intrusions, found by Cantex Mine Development Corporation in northwestern Yemen (Fig. 1), are located ~30 km apart [...]

Carbon isotopes are analyzed for the first time from the Ordovician-Silurian boundary interval in the Williston and Hudson Bay basins of Manitoba, revealing a prominent positive excursion. The nature of this excursion and its co- occurrence with the appearance of the Ozarkodina hassi Conodont Zone and a distinctive coral-dominated macrofauna indicate that this is the upper portion (Metabolograptus persculptus Graptolite Zone) of the globally recognized Hirnantian isotopic carbon excursion (HICE). As a result, the Ordovician-Silurian boundary is placed at a higher position than previously thought, at the disconformable Stonewall--Fisher Branch formational boundary in the Williston Basin, and probably the Port Nelson--Severn River formational boundary in the Hudson Bay Basin. Disconformities within sections suggest periods of nondeposition due to subaerial exposure as sea level fluctuated during the Late Ordovician glaciation. Latest Ordovician (Hirnantian) deposition was far more widespread on the Laurentian craton than realized previously. Age determination and correlation having unprecedented precision are attainable within and between the Williston and Hudson Bay basins, and beyond. Les isotopes du carbone de l'intervalle de la limite Ordovicien-Silurien des bassins de Williston et de la baie d'Hudson au Manitoba sont analyses pour la premiere fois, revelant une importante excursion positive. La nature de cette excursion et sa co-occurrence avec l'apparition de la zone a conodonte Ozarkodina hassi et une macrofaune distinctive dans laquelle predominent les coraux indiquent qu'il s'agit de la partie superieure (zone a graptolite Metabolograptus persculptus) de l'excursion hirnantienne d'isotopes du carbone (HICE) reconnue a l'echelle mondiale. Aussi, la limite Ordovicien-Silurien est placee dans une position plus elevee qu'auparavant, a la limite discordante entre les Formations de Stonewall et de Fisher Branch dans le bassin de Williston et probablement a la limite des Formations de Port Nelson et de Severn River dans le bassin de la baie d'Hudson. Des discordances dans les coupes laissent croire a des periodes de non-depot resultant de l'exposition subaerienne associee a des fluctuations du niveau de la mer durant la glaciation de l'Ordovicien tardif. La sedimentation a l'Ordovicien tardif (Hirnantien) etait beaucoup plus repandue dans le craton laurentien que ce qui etait envisage auparavant. Des degres de precision sans precedent dans la determination et la correlation des ages sont maintenant possibles au sein des bassins de Williston et de la baie d'Hudson, ainsi qu'entre ces bassins et au-dela. [Traduit par le Redaction], Introduction Lithostratigraphic and biostratigraphic successions in the latest Ordovician (international Hirnantian; North American Gamachian) were influenced globally by widespread glaciation in south polar Gondwana (Melchin et al. 2013; Ghienne et [...]

The Carboniferous Bay St. George subbasin is in southwestern Newfoundland, south of the Port au Port Peninsula. The Bay St. George subbasin is an onshore-to-offshore basin with a geologically complex [...]

The northwest Gander region has a complex glacial history influenced by multiple ice flows including an ice streaming event, and marine incursion as ice retreated during deglaciation. This complexity is [...]

Although considerable work has been conducted on the stratigraphy and dinosaur assemblages of the Horseshoe Canyon Formation of southern Alberta, equivalent strata and assemblages in central Alberta remain poorly understood. Data from the Danek Bonebed (Edmonton, Alberta) are beginning to fill this gap. The bonebed occurs 4 m above the #9 Big Island Coal Seam. This stratigraphic position lies just below the middle of the Horseshoe Canyon Formation in the Edmonton region, and also lies below a thick, stratigraphically significant non-coaly interval that is expressed throughout central and southern Alberta. The stratigraphic position of the Danek Bonebed equates best with the uppermost Horsethief Member of the Horseshoe Canyon Formation in the Drumheller region and the upper part of Unit 4 of the Wapiti Formation in the Grande Prairie region. In both Drumheller and Grande Prairie, the correlated position of the bonebed underlies a zone of marine transgression (Drumheller Marine Tongue), which, in turn, includes the Campanian-Maastrichtian boundary. In the context of Geologic Time Scale 2004, we infer a late Campanian age of 71.0-71.3 Ma for the bonebed. The Danek's dinosaurian assemblage is limited taxonomically, but compares well with the Edmontosaurus regalis--Pachyrhinosaurus canadensis fossil assemblage zone in the Drumheller region. We propose that a mega-herbivore faunal assemblage, characterized by Edmontosaurus and Pachyrhinosaurus, extended continuously across the climatically wet coastal plain of latest Campanian southern and central Alberta, and likely extended northwest into the North Slope of Alaska, where it persisted into the early Maastrichtian. Bien que beaucoup de travail ait ete fait sur la stratigraphie et les assemblages de dinosaures de la Formation de Horseshoe Canyon du sud de l'Alberta, l'equivalence des strates et des assemblages dans le centre de l'Alberta demeure mal comprise. Des donnees provenant du <> Danek (Edmonton, Alberta) commencent a combler ce manque. Le lit d'os se trouve a 4m au-dessus du lit de charbon no 9, Big Island. Cette position stratigraphique est juste sous le milieu de la Formation de Horseshoe Canyon dans la region d'Edmonton; elle se trouve aussi sous un intervalle epais, d'importance stratigraphique, mais qui ne contient pas de charbon et qui est exprime a travers tout le centre et le sud de l'Alberta. La position stratigraphique du lit d'os Danek correspond le mieux au membre sommital Horsethief de la Formation de Horseshoe Canyon dans la region de Drumheller, et a la partie superieure de l'unite 4 de la Formation de Wapiti dans la region de Grande Prairie. A Drumheller et a Grande Prairie, la position correlee du lit d'os se trouve sous une zone de transgression marine (langue marine de Drumheller), laquelle, a son tour comprend la limite Campanien-Maastrichtien. D'apres l'echelle des temps geologiques 2004, nous concluons un age de 71,0 a 71,3 Ma pour le lit. L'assemblage dinosaurien Danek est limite en termes de taxonomie mais il se compare bien a la zone d'assemblage fossilifere a Edmontosaurus regalis--Pachyrhinosaurus canadensis dans la region de Drumheller. Nous proposons un mega-assemblage de faune herbivore, caracterise par Edmontosaurus et Pachyrhinosaurus, qui s'etendait de maniere continue a travers la plaine cotiere, a climat humide, du Campanien sommital du sud et du centre de l'Alberta; ce megaassemblage s'etendait probablement aussi vers le nord-ouest dans le versant nord de l'Alaska, oU il a ete preserve jusqu'au Maastrichtien precoce. [Traduit par le Redaction], Introduction The Edmontosaurus-rich Danek Bonebed occurs along Whitemud Creek in Edmonton and serves as an important window through which latest Cretaceous non-marine environments and ecosystems can be assessed. More specifically, [...]

The current understanding of Lake Warren as a proglacial lake stage in the Lake Erie basin during the last deglaciation is based on limited stratigraphic information from strandlines and a wide range of radiocarbon ages. The purpose of this study is to use ground-penetrating radar (GPR) and optically stimulated luminescence (OSL) dating to reconstruct the stratigraphy, depositional environment, and age of the Oak Openings Ridge (OOR), a former strandline of Lake Warren in northwestern Ohio. Both sedimentary exposures and >4 km of GPR data were used to demonstrate that the OOR is a barrier spit that migrated from the northeast to the southwest, and is currently blanketed by an aeolian sheet. Sediments observed in exposures show a shallowing-up sequence attributed to the retreat of proglacial lakes from the area. Corresponding GPR data reveal three distinct GPR facies. The lowermost radar facies 1 (RF1) is a sandy barrier spit platform of a lower beach face prograding across finer-grained lacustrine mud or till. Eroded into RF1 is an upper beach face of RF2, the top of which is visible in cutbank and borrow pit exposures. Overlying the RF2 beach face is uppermost unit RF3, consisting of low-relief, aeolian parabolic dunes and sand sheets. Four OSL ages from a climbing ripple sequence in RF2 average 14.2 ± 0.5 ka, consistent with an earlier published OSL age of 14.1 [+ or -] 1.0 ka (Campbell et al. in 2011) from the same unit. From earlier work, the overlying aeolian dunes (RF3) record westerly winds after formation of the OOR, and OSL dating records episodic activity from the Younger Dryas chronozone to ~8000 years ago. The results suggest that the OOR formed in two phases. First, a barrier spit prograded into Lake Warren from the northeast. Second, parabolic sand dunes and a sand sheet formed episodically for ~5000 years thereafter. The sediment source for the sand body is from southeast Michigan, but it is of uncertain origin. Notre comprehension actuelle du lac Warren en tant qu'une etape de lac proglaciaire dans le bassin du lac Erie durant la derniere deglaciation est basee sur de l'information stratigraphique limitee d'anciennes lignes de rivage et d'une vaste plage d'ages [sup.14]C. Le but de la presente etude est d'utiliser des donnees georadar et de datation par luminescence stimulee optiquement (OSL) pour reconstruire la stratigraphie, l'environnement de deposition et l'age de la crete Oak Openings (OOR), une ancienne ligne de rivage du lac Warren dans le nord-ouest de l'Ohio. Des affleurements de roches sedimentaires et plus de 4 km de donnees georadar ont ete utilises pour demontrer que l'OOR est une fleche littorale qui a migre du nord-est au sud-ouest et qui est actuellement recouverte d'une couche de depots eoliens. Les sediments observes dans les affleurements montrent une sequence moins profonde vers le haut attribuee au retrait des lacs proglaciaires de la region. Les donnees georadar correspondantes revelent trois facies georadar distincts. Le facies georadar inferieur (RF1) est une plateforme de fleche littorale sableuse d'un front de plage inferieur qui prograde sur des boues lacustres ou un till a grain plus fin. Un front de plage superieur de RF2 est erode dans RF1; le sommet de ce front est bien visible dans les affleurements de berges hautes et dans les carrieres d'emprunt. L'unite superieure RF3, composee de dunes paraboliques eoliennes et de nappes de sable, repose sur le front de plage RF2. Quatre ages, determines par OSL sur une sequence ascendante de rides dans RF2 ont une moyenne de 14,2 ± 0,5 ka, ce qui concorde avec un age de 14,1 ± 1,0 ka (Campbell et al. en 2011) pour la meme unite. En se basant sur des travaux anterieurs, les dunes eoliennes sus-jacentes (RF3) enregistrent des vents d'ouest apres la formation de l'OOR, et la datation par OSL enregistre de l'activite episodique depuis la chronozone du Dryas inferieur a il y a environ 8000 ans. Selon les resultats, l'OOR se serait forme en deux phases. Tout d'abord, une fleche littorale a prograde dans le lac Warren depuis le nord-est. Par la suite, des dunes paraboliques et une couche de sable se sont formees de maniere episodique durant environ 5000 ans. Les sediments pour l'amas de sable proviendraient d'une source au sud-ouest du Michigan mais son origine est incertaine. [Traduit par la Redaction], Introduction One approach to elucidating the deglacial history of the Great Lakes basins is to gather depositional histories and chronological information by examining the surficial geology and geomorphology of strandlines. [...]

Terraces in the lower Matane River Valley (eastern Quebec, Canada) were studied to describe the stratigraphic architecture of a glacially eroded valley fill. The Matane River Valley hosted a glacial tongue connected with a regional ice cap during the early opening of a calving bay in the modern St. Lawrence Estuary and was subsequently flooded by the Goldthwait Sea as the Laurentide Ice Sheet margin retreated. Stratigraphic, sedimentological, light detection and ranging (LIDAR), and geochemical analyses as well as radiocarbon measurements allowed the identification of four stratigraphic units deposited during and following deglaciation: glacial outwash (unit I), delta bottomsets (unit II), delta foresets (unit III), and fluvial deposits (unit IV). Stable isotope ([sup.13]C) and C/N ratio values reveal the relative influence of the two end-members (algae and terrestrial plants) on organic matter sources between the stratigraphic units. Climate, major relative sea level fluctuations, and sediment yield are recognized as the main controls on depositional environments in glacially eroded valleys of the northern shore of the Gaspe Peninsula during the Holocene. This paper presents a model of the evolution of the Matane River Valley, which in many points is similar to existing conceptual fjord-valley fill models. Des terrasses dans la partie aval de la vallee de la riviere Matane (Est du Quebec, Canada) ont ete etudiees dans le but de decrire l'architecture stratigraphique d'une vallee erodee par les glaciers. La vallee de la riviere Matane a abrite une langue glaciaire qui etait reliee a une calotte glaciaire regionale durant l'ouverture precoce d'une baie de velage dans l'estuaire moderne du fleuve Saint-Laurent. La vallee fat par la suite inondee par la mer de Goldthwait a mesure du retrait de l'Inlandsis laurentidien. Des analyses stratigraphiques, sedimentologiques, geochimiques et par LIDAR (detection et telemetrie par ondes lumineuses) ainsi que des mesures au carbone 14 ont permis l'identification de quatre unites stratigraphiques deposees durant et apres la deglaciation: des depots d'epandage fluvioglaciaire (unite I), des lits basaux de delta (unite II), des lits frontaux de delta (unite III) et des depots fluviaux (unite IV). Des valeurs d'isotopes stables ([sup.13]C) et de rapport C/N revelent l'influence relative des algues et des plantes terrestres sur les sources de matiere organique entre les unites stratigraphiques. Le climat, les grandes fluctuations relatives du niveau de la mer et les sources de sediments constituent les principaux controles sur l'environnement de deposition dans les vallees erodees par les glaciers sur la rive nord de la peninsule gaspesienne durant l'Holocene. Cet article presente un modele de revolution de la vallee de la riviere Matane, laquelle ressemble en plusieurs points aux modeles conceptuels existants de vallees de fjords., Introduction Alluvial systems are the scene of major environmental changes during glacial-interglacial transitions (Abreu and Anderson 1998). Streams fed from glacier melt display highly variable flows and sediment discharges, filling [...]

ABSTRACT Thick conglomerate-dominated sedimentary successions of the Horton and lower Windsor groups in the southern Isle Madame area show provenance variations with stratigraphic position, based on pebble counts, petrographic observations, [...]

Sediments and stratigraphy at the Tower Buried Forest site provide a glimpse into the immediate post-glacial environment of northern Lower Michigan, USA. At this site, sandy glacial outwash is overlain by (1) ≅37 cm of peat associated with a wetland, above which are (2) flat-lying spruce and larch logs and branches that date between [much less than]10 910 and 10 340 cal years BP. Above the woody materials are ≅55-75 cm of sand, interbedded with organic muck laminae, which we interpret as local alluvium. This stratigraphic sequence is overlain by muck soil materials associated with the modern wetland. Pollen and plant macrofossil analysis of the lower peat indicate that a tundra-boreal parkland had been established here, shortly after final deglaciation. Later, Picea glauca (white spruce), Picea manana (black spruce), Larix laricina (larch), and Abies balsamea (balsam fir) became abundant in an open boreal forest--Spaghnum peatland. Subsequent increases in Pinus (pine) and Typha (cattail) indicate drying and possibly warming conditions. At ca. 10 340 cal years BP (or a few centuries prior), nearly two millennia after final deglaciation, water flowed across the site, possibly knocking over the trees. Interbedded sand and muck deposits above the flat-lying logs are interpreted as alluvial deposits from this event, after which the wetland became quiescent again. Les sediments et la stratigraphie dans la localite de la foret ensevelie de Tower ouvrent une fenetre sur un milieu etabli immediatement apres le retrait des glaciers, dans la partie nord du Bas-Michigan (Etats-Unis). A cet endroit, des depots d'epandage fluvioglaciaire sableux sont recouverts de (1) [est environ egal a] 37 cm de tourbe associee a un milieu humide, au-dessus de laquelle se trouvent (2) des troncs et branches d'epinettes et de melezes reposant a l'horizontale, dont les ages se situent entre [est environ egal a]10 910 annees etalonnees avant aujourd'hui (ans AA) et 10 340 ans AA. Au-dessus du materiel ligneux reposent [est environ egal a]55-75 cm de sable avec de minces interlits de terre tourbeuse organique que nous interpretons comme representant des alluvions de source locale. Cette sequence stratigraphique est recouverte de terre tourbeuse associee au milieu humide moderne. L'analyse de pollens et de macrofossiles de vegetaux de la tourbe inferieure indique qu'une foret-parc boreale et de toundra s'est etablie a cet endroit peu apres la deglaciation finale. Picea glauca (l'epinette blanche), Picea mariana (l'epinette noire), Larix laricina (le meleze laricin) et Abies balsamea (le sapin baumier) sont par la suite devenus abondants dans un paysage ouvert de foret boreale et de tourbiere de sphaigne. L'augmentation subsequente de l'abondance des Pinus (pins) et des Typha (quenouilles) indique une tendance vers des conditions plus seches et possiblement plus chaudes. Vers 10 340 ans AA (ou quelques siecles plus tot), pres de deux millenaires apres la deglaciation finale, de l'eau a deferle sur le site, abattant possiblement les arbres. Les depots de sable et de terre tourbeuse interlites recouvrant les troncs couches a l'horizontale sont interpretes comme etant des depots alluviauxmis en place durant cet episode, apres quoi le milieu humide est redevenu calme. [Traduit par la Redaction], Introduction Sparse vegetation cover on the recently deglaciated, Late Pleistocene landscapes of the Midwest, USA (e.g., Webb et al. 1983; Curry and Yansa 2004; Hupy and Yansa 2009; Curry and [...]

Geological investigation of the rocks in the Elu Link has provided new information on the geodynamic origin of the Neoarchean (ca. 2716-2663 Ma) Hope Bay and Elu granite-greenstone belts. Stratigraphic and geochemical features of these rocks and those of the nearby Flake Lake area in the Hope Bay belt suggest that the two greenstone belts are contiguous, having similar mafic-dominated bimodal rocks comprising abundant basalts to andesites and less common dacites and rhyolites hosting gabbroic and trondhjemite-tonalite-granodiorite (TTG) intrusions. The corresponding parental magmas, whose evolution likely occurred via fractional crystallization and juvenile crustal contamination, formed from both deep and shallow mantle sources. The basalts, andesites, gabbros, and felsic volcanic rocks are variably tholeiitic to calc-alkaline. Chondrite- and primitive mantle-normalized profiles demonstrate (1) flat to slightly fractionated heavy rare-earth element (HREE) patterns with a weak negative Eu anomaly and (2) light rare-earth element (LREE) enriched and strongly fractionated HREE patterns with variable negative to positive Eu anomalies. In contrast, TTG rocks are calc-alkaline, with strong LREE enrichment, HREE depletion, and variable positive Eu anomalies. Altogether, the rocks exhibit Nb and Ti troughs, and variable Nb/Ta, La/Ta, and Zr/Hf ratios indicative of crustal contamination. Chalcophile elements and related ore deposits in the area are inferred to be formed from hydrothermal fluids mobilized during emplacement and after crystallization of their host rocks. An extensional, high- heat-flow back-arc tectonic environment is proposed to explain the stratigraphic and geochemical characteristics and the presence of large gold resources in these greenstone belts. Une etude geologique des roches dans le chainon Elu a fourni de nouvelles informations quant a l'origine geodynamique des ceintures granitiques-roches vertes de Hope Bay et d'Elu (Neoarcheen, ~2716-2663 Ma). Les caracteristiques stratigraphiques et geochimiques de ces roches et de celles du secteur avoisinant du lac Flake dans la ceinture de Hope Bay suggerent que les deux ceintures de roches vertes sont contigues, car elles presentent des roches bimodales similaires dominees par des roches mafiques comprenant d'abondants basaltes et andesites et, moins frequentes, des dacites et des rhyolites qui contiennent des intrusions gabbroiques et de trondhjemite-tonalite-granodiorite (TTG). Les magmas parentaux correspondants, qui ont probablement evolue par une cristallisation fractionnee et contamination crustale juvenile, proviennent de sources mantelliques profondes et de faible profondeur. Les basaltes, les andesites, les gabbros et les roches felsiques volcaniques sont tholeiitiques a calco-alcalines. Les profils normalises chondritiques et de manteau primitif montrent : (1) des patrons plats a legerement fractionnes d'elements des terres rares lourdes (HREE) montrant une anomalie Eu faiblement negative et (2) des patrons d'enrichissement d'elements de terres rares legeres (LREE) et des patrons de HREE fortement fractionnes montrant des anomalies en Eu negatives a positives. Par contre, les roches TTG sont calco-alcalines et montrent un fort enrichissement en LREE; un appauvrissement en HREE et des anomalies en Eu variables, mais positives. Dans l'ensemble, les roches presentent des creux Nb et Ti et des rapports Nb/Ta, La/Ta et Zr/Hf variables, indiquant une contamination de la croute. Les elements chalcophiles et les gisements de minerai associes dans le secteur auraient ete formes a partir de fluides hydrothermaux mobilises durant la mise en place et apres la cristallisation des roches hotes. Un environnement tectonique d'extension d'arriere-arc, a fort flux thermique, est propose pour expliquer les caracteristiques stratigraphiques et geochimiques ainsi que la presence de vastes ressources d'or dans ces ceintures de roches vertes. [Traduit par la Redaction], Introduction The origin and evolution of the Archean continental crust has for many years been the focus of multidisciplinary studies worldwide. In this global effort to understand Archean geodynamics and [...]

The ~51 Ma Montagnais impact crater on the outer Scotian Shelf is well known, but the potential effects from the impact event on the slope and rise seaward of the crater have, until now, remained poorly understood. Through detailed seismic stratigraphic correlation and ties to available wells, we define a threefold seismic stratigraphic subdivision for Upper Cretaceous to Eocene strata on the shelf and slope, calibrated to the most recent biostratigraphic results. Using this framework, we identify a number of depositional and erosional products that are temporally consistent with a late Ypresian impact event (within the limits of seismic and biostratigraphic resolution). We link a series of prominent failure scarps on the outer shelf and upper slope to a single widespread mass-transport deposit (MTD) on the lower continental slope, rise, and abyssal plain. Failed material amassed in a large debris field referred to here as the 'Montagnais MTD'. It covers an area of ~93 000 [km.sup.2] and travelled up to 580 km from the impact site where its distal termination onlaps the New England Seamounts, making it one of the largest known debris avalanches on Earth. We interpret these deposits, and the associated pattern of erosion landward of them, as products of widespread margin collapse caused by a combination of ground shaking and ensuing tsunamis triggered by the Montagnais impact event. This study provides insight into the potential effects of outer-shelf marine impact events immediately downslope from impact sites, and their diminished effects with increasing distance along the margin. Le cratere d'impact Montagnais, ~51 Ma, sur la plateforme externe Scotian, est bien connu mais les effets potentiels de l'impact sur la pente et l'elevation du cratere du cote de la mer sont, jusqu'a present, demeures mal compris. Grace a une correlation sismique detaillee et l'etablissement de liens avec des puits disponibles, nous definissons une triple subdivision stratigraphique sismique pour les strates du Cretace superieur a l'Eocene sur la plateforme et la pente, etalonnee en se basant sur les plus recents resultats biostratigraphiques. En utilisant ce cadre, nous identifions un certain nombre de produits de deposition et d'erosion qui concordent dans le temps avec un evenement d'impact a l'Ypresien tardif (a l'interieur des limites de la resolution sismique et biostratigraphique). Nous relions une serie de ruptures d'escarpements proeminents sur la plateforme externe et la partie superieure de la pente a un vaste depot unique de transport de masse (MTD) sur la partie inferieure de la plateforme continentale, la partie en elevation et la plaine abyssale. Le materiel de rupture s'est amasse dans un grand champ de debris que nous nommons ici le << Montagnais MTD >>. Il couvre une superficie ~93 000 [km.sup.2] et il atteint une distance de 580 km du site d'impact ou son extremite distale chevauche la chaine de monts sous-marins de la Nouvelle-Angleterre, ce qui en fait l'une des plus grosses avalanches de debris sur Terre. Nous interpretons ces depots, et le patron associe d'erosion du cote continental, comme etant les produits d'un vaste effondrement de la bordure cause par une combinaison de tremblements de terre et des tsunamis qui en ont decoule, declenches par l'evenement d'impact Montagnais. La presente etude donne un apercu des effets potentiels des evenements d'impact marins sur la plateforme externe, tout juste a l'aval des sites d'impact, et de leurs effets, lesquels s'attenuent avec l'accroissement de la distance le long de la bordure. [Traduit par la Redaction], Introduction Ground shaking associated with earthquakes is known to be a primary mechanism for triggering submarine mass failures that erode slopes and transfer large quantities of sediment into deeper water [...]

Stromatolites are abundant and widely distributed within two narrow stratigraphic intervals in Middle (Darriwilian) and Upper (lower Turinian) Ordovician strata of the Laurentian foreland interior in the Ottawa Embayment, eastern Ontario. These lithostratigraphic markers coincide with rapid, tectonically driven flooding of the foreland interior and may identify an opportunistic microbial response to nutrient loading with shallow (peritidal, subtidal) marine reworking of terrestrial or nutrient- rich coastal systems. The remaining (Chatfieldian-Edenian) foreland-platform succession represents deeper-water deposition in response to elevated subsidence rates along the Laurentian margin. Stromatolites are absent in this higher-energy setting, but microbial calcite is preserved as coccoid-like microencrustations on skeletal debris. Stromatolites of Darriwilian age are dolomitic, occur in the Carillon Formation, and are part of a regional (200+ km) onlap of peritidal sediment during onset of Taconic orogenesis. Stratiform to large (2 m diameter) low-relief domal stromatolites contain rhythmic laminations of inclusion-rich and -poor dolomicrospar grouped by Fe-oxide-stained erosional surfaces. Domal forms also contain thrombolitic microstructure. Patterns of lamination and stable (C, O) isotopes suggest a balance between abiotic and microbial carbonate production, likely influenced by water depth and temperature. Stromatolites of Turinian age are calcitic and form a regional (80+ km) thin ( Les stromatolithes sont abondants et largement dissemines dans deux minces intervalles stratigraphiques de strates de l'Ordovicien moyen (Darriwilien) et superieur (Turinien inferieur) de l'interieur de l'avant-pays laurentien dans le rentrant d'Ottawa de l'est de l'Ontario. Ces marqueurs lithostratigraphiques coincident avec l'inondation rapide d'origine tectonique de l'interieur de l'avant-pays et pourraient representer une reponse microbienne opportuniste a la charge en nutriments associee au remaniement marin peu profond (peritidal, infratidal) de systemes terrestres ou cotiers riches en nutriments. Le reste de la sequence (Chatfieldien-Edenien) de plate-forme-avant-pays represente une sedimentation a plus grande profondeur en reponse a des taux accrus de subsidence le long de la marge laurentienne. Si les stromatolithes sont absents de ce milieu plus energique, de la calcite d'origine microbienne est preservee sous forme de microincrustations d'allure cocciforme sur des debris squelettiques. Les stromatolithes d'age darriwilien sont dolomitiques, sont trouvent dans la Formation de Carillon et font partie d' une sequence regionale de recouvrement transgressif (de plus de 200 km) de sediments peritidaux mise en place au debut de l'orogenese taconique. Des domes stromatolithiques stratiformes a imposants (2 m de diametre) mais de faible relief contiennent des lamines rythmiques de dolomie microscopique riche et pauvre en inclusions regroupees par des surfaces d'erosion tachees d'oxydes de fer. Les domes contiennent egalement des microstructures thrombolitiques. La distribution des lamines et des isotopes stables (C, O) suggere un equilibre entre la production abiotique et microbienne de carbonates, vraisemblablement influencee par la profondeur et la temperature de l'eau. Les stromatolithes d'age turinien sont calcitiques et forment une mince ( [Traduit par la Redaction], Introduction Microbialites are benthic microbial deposits (Burne and Moore 1987) that include stromatolites, which are macroscopically layered with or without abiogenic precipitates (Riding 2011), and thrombolites that possess no distinctive [...]

The Lower to Middle Jurassic Hazelton Group represents the final stage of magmatic arc activity in the intraoceanic Stikine terrane, which was followed by accretion within the Cordilleran terrane collage. The Hazelton Group is exposed in the following areas: (i) on the periphery of the Bowser Basin, where arc and back-arc strata are overlain by mainly sedimentary strata of the upper Hazelton Group and then by the clastic basin fill of the Bowser Lake Group; and (ii) within a 300 km long rift system, the Eskay rift, west of the Bowser basin, where a predominantly bimodal volcanic succession contains significant mineral deposits. Examination of representative stratigraphic sections throughout the regional extent of the upper Hazelton Group has suggested significant revisions and clarification of its stratigraphy and include the following: (i) informal division of the Hazelton Group into upper and lower parts and recognition of a diachronous unconformity or unconformities at the boundary between them; (ii) establishment of a type section for the sandstone-dominated Smithers Formation; (iii) establishment of separate Quock and revised Spatsizi formations in the north and extension of the Quock Formation to include all lithostratigraphically equivalent units of blocky, thinly bedded siliceous mudstone and tuff around the periphery of the Bowser basin; and (iv) introduction of the Iskut River Formation for rift-related and volcanic facies in the Eskay rift area. Two independent rifting events occurred during deposition of the Hazelton Group: a Late Sinemurian to Early Pliensbachian phase in the northwest-trending Hazelton trough and a more restricted Aalenian to Bajocian extensional event in the Eskay rift. Le Groupe de Hazelton (Jurassique inferieur a moyen) represente l'etape finale d'activite d'arc magmatique dans le terrane intra-oceanique Stikine, laquelle fut suivie par son accretion dans le collage de terranes de la Cordillere. Le Groupe de Hazelton affleure : (i) a la peripherie du bassin Bowser, ou des strates d'arc et d'arriere-arc sont recouvertes par des strates surtout sedimentaires du Groupe de Hazelton superieur et ensuite par le remplissage clastique de bassin du Groupe de Bowser Lake et (ii) dans un systeme de rifts d'une longueur de 300 km, le rift Eskay, a l'ouest du bassin Bowser, ou une succession volcanique principalement bimodale contient des gites mineraux significatifs. Un examen de sections stratigraphiques representatives a travers l'etendue regionale du Groupe de Hazelton superieur suggere d'importantes revisions et precisions de sa stratigraphie dont : (i) une division informelle du Groupe de Hazelton en parties inferieure et superieure et la reconnaissance d'une ou de plusieurs discordances diachroniques a la limite entre les parties; (ii) l'etablissement d'une section-type pour la Formation de Smithers, dominee par des gres; (iii) l'etablissement, au nord, d'une Formation de Quock distincte ainsi qu'une revision de la Formation de Spatsizi et l'extension de la Formation de Quock pour inclure toutes les unites a equivalence lithostratigraphique de mudstone et de tufs siliceux, a blocs et a lits minces, autour du bassin Bowser et (iv) l'introduction de la Formation d'Iskut River pour les facies volcaniques et ceux relies au rift dans la region du rift Eskay. Deux evenements independants de distension ont eu lieu durant la deposition du Groupe de Hazelton : une phase (Sinemurien tardif a Pliensbachien precoce) a tendance nord-ouest dans la fosse Hazelton et un evenement d'extension plus restreint (Aalenien a Bajocien) dans le rift Eskay. [Traduit par la Redaction], Introduction The Jurassic Period marks a key transition in the tectonics of the Canadian Cordillera. During this time, the western margin of North America was changing rapidly from a complex [...]

The Upper Cretaceous paralic to nonmarine Horseshoe Canyon Formation (HCFm) of southern Alberta is divided into seven mappable members: Strathmore, Drumheller, Horsethief, Morrin, Tolman, Carbon, and Whitemud (bottom to top). This subdivision, based on combined outcrop and subsurface analyses, reflects lithostratigraphic variations related to changes in sea level (previously recognized) and newly documented changes in climate, volcanism, and orogenesis in an evolving foreland basin. Million-year-scale cycles of orogenesis resulted in changes in sediment supply and rates of subsidence in the basin and are interpreted in the context of a simple, two-phase foreland-basin sequence stratigraphic model: (i) overthrust loading resulting in reduced rates of sediment supply and subsidence in the most distal portions of the Alberta foredeep (our field area); (ii) tectonic quiescence leading to increased rates of sediment supply and subsidence during proximal-foredeep rebound. During the first ~2.5 Ma of its history (Strathmore and Drumheller members), the HCFm was tectonically and climatically 'stable', and depositional style and stratigraphic architecture were influenced by vertical aggradation and modest progradation of shorelines. During the remaining ~4.5 Ma (Horsethief, Morrin, Tolman, Carbon, and Whitemud members), there were more complex and frequent changes in climate, volcanism, orogenesis, landscape weathering, and soil formation. Understanding this previously unrecognized complexity is critical for correctly assessing hydrocarbon resource distributions and biostratigraphic and taphonomic patterns. La Formation de Horseshoe Canyon (HCFm) du sud de l'Alberta est divisee en sept membres cartographiables : Strathmore, Drumheller, Horsethief, Morrin, Tolman, Carbon et Whitemud (du bas vers le haut). Cette subdivision, basee sur une combinaison d' analyses de roc affleurant et de roc sous la surface, reflete les variations lithostratigraphiques relatives aux changements du niveau de la mer (reconnus anterieurement) et les nouveaux changements documentes de climat, de volcanisme et d'orogenese dans un bassin d'avant-pays en constante evolution. Des cycles de millions d'annees d'orogenese ont produit des changements dans l' apport de sediments ainsi que dans les taux de subsidence du bassin; ces cycles sont interpretes dans le contexte d'un modele stratigraphique simple de sequence a deux phases de bassin d'avant-pays : (i)un chargement par chevauchement qui reduit les taux d' apport de sediments et de subsidence dans les portions les plus distales de l'avant-fosse de l'Alberta (notre secteur); (ii) une quiescence tectonique qui mene a un accroissement des taux d'apport de sediments et de subsidence lors du soulevement de l'avant-fosse proximale. Au cours des premiers ~2,5 Ma de son histoire (les membres Strathmore et Drumheller), la HCFm etait tectoniquement et climatiquement stable; le style de deposition et l' architecture stratigraphique etaient influences par une aggradation verticale et une legere progradation des littoraux. Au cours des ~4,5 Ma suivants (membres Horsethief, Morrin, Tolman, Carbon et Whitemud), il y eut des changements climatiques plus complexes et plus frequents, ainsi que du volcanisme et des orogeneses; le paysage a ete modifie et des sols ont ete formes. Il est essentiel de comprendre cette complexite, non reconnue anterieurement, pour bien evaluer la distribution des reservoirs d' hydrocarbures ainsi que les formes biostratigraphiques et taphonomiques. [Traduit par la Redaction], Introduction The stratigraphy of the paralic to nonmarine Upper Cretaceous Horseshoe Canyon Formation (HCFm) in southern Alberta has been described in a succession of publications since the late 1800s (e.g., [...]

We present a detailed cryostratigraphic reconstruction of the degradation and recovery of near-surface permafrost in the southern Klondike goldfields, central Yukon Territory. Two ice-rich layers are recognized in near-surface permafrost and attributed to thermal impacts following vegetation disturbance. At an undisturbed forest site, the base of the modern active layer is stable. At an adjacent site, where a late twentieth century disturbance of surface vegetation and permafrost degradation occurred, there is evidence of recovery in the form of aggradation (upward shift) of the permafrost table following limited vegetation succession. Underlying both the undisturbed forest and the late twentieth century disturbance is an older thaw unconformity corresponding to a thaw depth of ~2 m, likely associated with early twentieth century (gold rush era) impacts. Field and air photo surveys allow identification of the nature of the disturbances, while a chronology of the surface disturbance has been established using age estimates from tree rings, and the presence of tritium and post-bomb [sup.14]C from organic samples within aggradational ice. Collectively, these data underscore the importance of vegetation cover in maintaining ground temperatures in the discontinuous permafrost zone and suggest that, at least at the study site in recent decades, permafrost shows the potential to recover from disturbance in the modern climatic regime of the region. Nous presentons une reconstruction cryostratigraphique de la degradation et du retablissement du pergelisol pres de la surface dans les champs auriferes du sud du Klondike, au centre du Territoire du Yukon. Deux couches riches en glace sont reconnues dans le pergelisol pres de la surface et elles sont attribuees a des impacts thermiques causes par une perturbation de la vegetation. A un site forestier non perturbe, la base de la couche moderne active est stable. A un site adjacent, ou est survenue une perturbation de la vegetation en surface et une degradation du pergelisol a la fin du 20 siecle, il existe des evidences de retablissement sous la forme d'aggradation (mouvement vers le haut) de la limite du pergelisol apres une succession vegetale limitee. Sous la couche forestiere non perturbee et sous la perturbation de la fin du 20 siecle, on retrouve une ancienne discordance de degel correspondant a une profondeur de degel d'environ 2 m, probablement associee a des impacts survenus au debut du 20 siecle (l'epoque de la ruee vers l'or). Des releves sur le terrain et des photos aeriennes permettent d' identifier la nature des perturbations et une chronologie des perturbations de la surface a ete etablie par dendrochronologie ainsi que par la presence de tritium et de [sup.14]C post-bombardements a partir d'echantillons organiques dans la glace d' aggradation. Ensemble, ces donnees soulignent l' importance de la couverture vegetale pour maintenir les temperatures du sol dans la zone de pergelisol discontinu et suggerent que, du moins dans le secteur a l' etude au cours des dernieres decennies, le pergelisol puisse se retablir des perturbations dans le regime climatique moderne de la region. [Traduit par la Redaction], Introduction Areas underlain by permafrost represent ground conditions in which the prevailing climate, surface properties, and vegetation cover interact to produce long-term ground temperatures below 0°C. This thermal state has [...]

Every environmental site investigation aims at delineating near-surface (hydro-) stratigraphic units and their characterization. To determine the type and hydraulic properties of sedimentary deposits, direct push (DP) sensor probes and tools are promising methods and are therefore frequently applied to measure high-resolution vertical profiles of soil properties. Given the variety of these tools, the objective of this paper is to compare selected DP tools for the (hydro-) stratigraphic subsurface characterization in a heterogeneous unconsolidated sedimentary aquifer. An overview of current DP applications is given and selected DP tools were tested for reproducibility, as well as their ability to reflect soil variability and to estimate hydraulic conductivity, K. Although resolution differences exist, all of the applied methods captured the main aquifer structure. Correlations of the DP-based K estimates or proxies with DP slug tests (DPST) show that it is possible to describe the aquifer hydraulic structure on less than a metre scale by combining DPST data and continuous DP measurements. Although correlations are site-specific and appropriate DP tools must be chosen, DP is a reliable and efficient alternative for characterizing even strongly heterogeneous sites with complex sedimentary architectures. Key words: direct push, aquifer characterization, hydraulic profiling, cone penetration testing. Les etudes environnementales de sites servent a identifier et caracteriser les unites (hydro-) stratigraphiques pres de la surface. Afin de determiner le type de depots sedimentaires et leurs proprietes hydrauliques, les sondes et outils de poussee directe (PD) font partie des methodes prometteuses, et ainsi sont frequemment appliques pour mesurer a haute resolution les profils verticaux des proprietes des sols. Comme ces outils sont nombreux et varies, l'objectif de cet article est de comparer certains de ces outils de PD pour la caracterisation (hydro-) stratigraphique sous la surface dans un aquifere sedimentaire heterogene et non consolide. Un sommaire des applications courantes de PD est presente, et certains outils ont ete testes pour evaluer leur reproductibilite ainsi que leur capacite a identifier la variabilite des sols et a estimer la conductivite hydraulique, K. Meme si les methodes appliquees different dans leur resolution, elles ont toutes reussi a evaluer la structure de l' aquifere principal. Des correlations entre les estimations de K basees sur la PD ou obtenues indirectement avec des essais de cone en PD (ECPD) demontrent qu'il est possible de decrire la structure hydraulique d'un aquifere a une echelle inferieure au metre en combinant les donnees d' ECPD et les mesures en continu de PD. Malgre que les correlations soient specifiques a un site donne et que les outils de PD appropries doivent etre choisis, la PD est une alternative efficace et fiable pour caracteriser les sites tres heterogenes ayant des architectures sedimentaires complexes. Mots-cles : poussee directe, caracterisation d'aquifere, profilage hydraulique, essai de penetration du cone. [Traduit par la Redaction], Introduction Environmental site investigations require high-resolution information about lithology and hydraulic properties of the subsurface. Knowledge of the spatial distribution of hydraulic conductivity (K) is the prerequisite for understanding flow [...]

The Partridge Island stratigraphic section at the Bay of Fundy, Maritime Canada, reveals a continental sedimentary succession with the end-Triassic mass extinction level closely followed by basalts of the Central Atlantic Magmatic Province (CAMP). New Paleomagnetic data show that a short reverse magnetic polarity chron, correlative to E23r of the Newark Geomagnetic Polarity Time Scale (GPTS), is present below the extinction event. Organic carbon isotope data and basalt geochemistry further indicate that the onset of CAMP emplacement in the Bay of Fundy was roughly synchronous with emplacement in the Newark basin, but slightly postdates the oldest CAMP volcanism in Morocco by ~20 ka. These results confirm the potential for long-distance CAMP correlations based on geochemical trace elements, indicate substantiate provincialism of latest Triassic palynoflora, and suggest a very concise period (≫ 100 ka) of CAMP emplacement in the northern Atlantic region. La section stratigraphique de l'ile Partridge dans la baie de Fundy, Maritimes, Canada, revele une succession sedimentaire continentale dans laquelle le niveau d'extinction massive de la fin du Trias est suivi de pres par des basaltes de la Province magmatique centre atlantique (CAMP). De nouvelles donnees paleomagnetiques montrent qu'un chrone de breve inversion de polarite magnetique, correle a E23r de l'echelle de temps geomagnetique de polarite de Newark, est present sous l' evenement d' extinction. Des donnees d' isotopes du carbone organique et la geochimie des basaltes indiquent de plus que le debut de la mise en place de la CAMP dans la baie de Fundy a ete passablement contemporain avec la mise en place du bassin Newark, mais cette mise en place a eu lieu peu de temps apres le plus ancien volcanisme CAMP au Maroc, soit environ 20 ka. Ces resultats confirment le potentiel de correler la CAMP sur de longues distances, en se basant sur des elements traces geochimiques; ils indiquent et valident le provincialisme de la plus recente palynoflore du Trias et suggerent une tres courte periode (≫ 100 ka) pour la mise en place de la CAMP dans la region de l'Atlantique Nord. [Traduit par la Redaction], Introduction The end-Triassic mass extinction (~201.4 Ma Schoene et al. 2010) is considered to be one of the 'big five' extinction events in geological history (Raup and Sepkoski 1982; Sepkoski [...]

The south-central Intermontane belt of British Columbia has a complex architecture comprising late Paleozoic to Mesozoic volcanic and plutonic arc magmatic suites, marine and nonmarine clastic basins, high-grade metamorphic complexes, and accretionary rocks. Jurassic and Cretaceous clastic basins within this framework contain stratigraphy with hydrocarbon potential. The geology is complicated by Cretaceous to Eocene deformation, dismemberment, and dislocation. The Eocene to Neogene history of the southern Intermontane belt is dominated by non-arc volcanism, followed by Pleistocene to Recent glaciation. The volcanic and glacial cover makes this a difficult region to explore for resources. Much recent work has involved re-evaluating the challenges that the overlying volcanic cover has historically presented to geophysical imaging of the sedimentary rocks in this region in light of technological advances in geophysical data collection and analysis. This paper summarizes the lithological and stratigraphic framework of the region, with emphasis on description of the sedimentary units that have been the targets of hydrocarbon exploration. La ceinture intermontagneuse du centre-sud de la Colombie-Britannique a une architecture complexe (Paleozoique a Mesozoique) comprenant des suites magmatiques, volcaniques et d'arcs plutoniques, des bassins clastiques marins et non marins, des complexes a metamorphisme eleve et des roches d'accretion. Les bassins clastiques du Jurassique et du Cretace dans ce cadre comprennent une stratigraphie a potentiel d'hydrocarbures. La geologie a ete rendue complexe par des deformations, des demembrements et des dislocations du Cretace a l'Eocene. L'historique de l'Eocene au Neogene de la ceinture intermontagneuse sud est domine par un volcanisme ne provenant pas d'arcs, suivi d'une glaciation du Pleistocene au Recent. La couverture volcanique et glaciaire de la region complique l'exploration pour des ressources. Etant donne les progres technologiques dans la collecte et l'analyse de donnees geophysiques, une grande partie des travaux recents comprenaient la reevaluation des defis que presentait historiquement la couverture volcanique a obtenir une imagerie geophysique des roches sedimentaires de la region. Le present article resume le cadre lithologique et stratigraphique de la region, mettant l'accent sur la description des unites sedimentaires qui ont ete ciblees pour la recherche d'hydrocarbures. [Traduit par la Redaction], Introduction This paper outlines a lithostratigraphic framework for sedimentary successions of the south-central Intermontane belt, and provides descriptions for the exposed successions, to provide a context for other papers in [...]

Five distinctive tephra beds are preserved in fine-grained sediments on a prominent terrace strath along the lower Sixtymile River of the Yukon Territory. Commencing with the oldest unit, they are TA, SM3, Gold Run, Hollis 2, and Flat Creek tephra beds. The uppermost three tephra beds have rhyolitic compositions, the other two are bimodal with a much more basic glass phase. Three glass fission-track age determinations point to deposition during the early-Middle Pleistocene. We correct an error in an earlier study by clarifying that Flat Creek tephra is younger than Gold Run tephra, TA tephra is older. Cinq lits distincts de tephra sont presents dans des sediments a grain fin sur une importante terrasse rocheuse le long du cours inferieur de la riviere Sixtymile dans le Territoire du Yukon. En commencant par l'unite la plus ancienne, ces lits de tephra sont TA, SM3, Gold Run, Hollis 2 et Flat Creek. Les trois lits de tephra supeerieurs presentent des compositions rhyolitiques, les deux autres sont bimodales et comportent une phase de verre beaucoup plus basique. Trois determinations d'age par trace de fission sur verre indiquent une deposition au cours du Pleistocene moyen precoce. Nous corrigeons une erreur dans une etude anteerieure en precisant que le tephra Flat Creek est plus jeune que le tephra Gold Run, le tephra TA est plus ancien. [Traduit par la Redaction], Introduction Whilst assembling information for a catalogue of late Cenozoic tephra beds in the Klondike goldfields (Preece et al. in press), we noticed an error in the tephrostratigraphic record of [...]

[1] We combine detrital zircons (DZ) and epsilon neodymium ([[epsilon].sub.Nd]) signatures with field mapping in the Paro Formation in western Bhutan. DZ age spectra are strongly variable and display signatures that have been used to uniquely identify both Greater Himalayan (GH) and Lesser Himalayan (LH) strata. DZ age peaks from six quartzite samples require sources for ~0.5, 0.8, 1.2, 1.4, 1.7, 1.8, and 2.5 Ga zircons in the Paro Formation. The youngest (~0.5 Ga) zircons argue for a Cambrian maximum deposition age. Two samples have a youngest 1.8 Ga peak typically attributed to Paleoproterozoic LH rocks. A ~450 Ma crystallization age from two granite samples constrains the minimum deposition age as Ordovician. New [[epsilon].sub.Nd] signatures from six detrital samples from the Paro Formation show significant variation with lithology. Schists have [[epsilon].sub.Nd] (0) values between -12.0 and -16.9, while quartzite values vary between -18.8 and -24.5. These data imply that the Paro Formation was derived from both young and old sources, with DZ and [[epsilon].sub.Nd] values obtained from the same quartzite samples requiring old detritus while the end values obtained from interbedded schist require younger detritus. Using published isotopic and chronologic definitions of Himalayan strata, schist-rich layers would be considered GH, while the interbedded quartzite would be LH. Thus, the Paro Formation refutes the generally accepted notion that different Himalayan tectonostratigraphic zones have unique DZ and end signatures. Our data recommend caution in the use of DZ and [[epsilon].sub.Nd] signatures for tectonic interpretation, especially when making correlations with studies that extend 1000s of km along strike. Citation: Tobgay, T., S. Long, N. McQuarrie, M. N. Ducea, and G. Gehrels (2010), Using isotopic and chronologic data to fingerprint strata: Challenges and benefits of variable sources to tectonic interpretations, the Paro Formation, Bhutan Himalaya, Tectonics, 29, TC6023, doi: 10.1029/2009TC002637.

[1] The St. Elias orogen is the result of~10 Myr of oblique convergence and flat-slab subduction in the Gulf of Alaska between North America and the Yakutat microplate. Extensive glaciation and a complex tectonic environment make this region a unique case study in which to examine the details of terrane accretion and the possible coupled influence of climate and tectonic drivers on the structural and topographic evolution of an orogenic wedge. Reflection seismic profiles across the offshore Pamplona zone fold-thrust belt, the frontal St. Elias orogenic wedge, provide constraints for quantifying Pleistocene deformation recorded in the glaciomarine Yakataga formation. The total amount of Pleistocene shortening observed varies from ~3 to 5 mm/yr, compared to the current GPS-derived Yakutat-North America convergence rate across the St. Elias orogen of ~45 mm/yr. Growth strata and kinematic fold analysis allow comparison of relative timing of fault activity, which reveals temporal and spatial shifting of active deformation during the glacial period: faulting localized adjacent to the coastline and at the current submarine deformation front. The abandoned, currently inactive region is colocated with the major glacial depocenter in the region, the Bering Trough. These observations imply that glacial processes such as sediment loading and focused erosion during advance-retreat cycles has a direct effect on the evolution of individual faults within the Pamplona zone and the overall deformation pattern in the offshore St. Elias margin. This information provides key constraints for understanding how climatic shifts may have affected the evolution of margin architecture during Pleistocene glacial-interglacial periods. Citation: Worthington, L. L., S. P. S. Gulick, and T. L. Pavlis (2010), Coupled stratigraphic and structural evolution of a glaciated orogenic wedge, offshore St. Elias orogen, Alaska, Tectonics, 29, TC6013, doi: 10.1029/2010TC002723.

[1] Sedimentologic, provenance, oxygen isotope, and [.sup.40]Ar/[.sup.39]Ar results provide insights into late Cenozoic evolution of an extensional hinterland basin in the Peruvian Andes. The 5-6.5 km Cordillera Blanca composes the glaciated footwall of a low-angle normal fault parallel to active contractional structures in the Andean fold-thrust belt. The -200 km long, WSW dipping (19[degrees]-36[degrees]) Cordillera Blanca detachment fault accommodated > 12-15 km of dip-slip displacement, inducing subsidence of the hanging-wall supradetachment basin, which is filled by ~1300 m of conglomerate, sandstone, siltstone, and limited carbonate of the upper Miocene-Pliocene Lloclla Formation. Lithofacies associations are attributed to lacustrine fan-delta to proximal, stream-dominated alluvial fan sedimentation. Provenance data record footwall unroofing of Jurassic through Miocene volcanic and sedimentary rocks during NW directed, axial dispersal of sediment. Provenance data record the appearance of footwall-derived granite clasts from the upper Miocene Cordillera Blanca batholith and a change to transverse, WSW directed transport. Variations in the character and preservation of basin fill suggest along-strike propagation of the fault through time. Initial extension and subsidence is constrained to the latest Miocene by an 4[degrees]Ar/39Ar biotite age of 5.4 [+ or -] 0.1 Ma for a basal tuff in the Lloclla Formation. Estimation of paleolake water composition shows very negative [delta][sup.18](VSMOW) values (-13.6%0 to-18.2%o), indicating that high elevations comparable to modern were already attained in the Cordillera Blanca during earliest normal faulting and basin evolution. These results lend support to models suggesting that substantial shortening, crustal thickening, and surface uplift were necessary precursor conditions for the generation of the Cordillera Blanca detachment fault. Citation: Giovanni, M. K., B. K. Horton, C. N. Garzione, B. McNulty, and M. Grove (2010), Extensional basin evolution in the Cordillera Blanca, Peru: Stratigraphic and isotopic records of detachment faulting and orogenic collapse in the Andean hinterland, Tectonics, 29, TC6007, doi: 10.1029/2010TC002666.

New 3D seismic-reflection data from the northern San Joaquin Valley (Great Valley forearc basin), California, provide the first convincing evidence of emergence and erosion of the Franciscan subduction complex during the Mesozoic. Syntectonic growth strata record an early Maastrichtian phase of deformation, which elevated the subduction complex above sea level. Once exposed, erosion generated a supply of sediment that built a progradational wedge (arcward) into bathyal waters of the forearc basin. The thickness and extent of these subduction complex--derived sediments argue for an a really extensive landmass located west of the forearc basin. Regional emergence of the subduction complex suggests that erosion served as a significant driver in the exhumation of Franciscan blueschists. doi: 10.1130/B30180.1

A composite magnetostratigraphy based on the magnetic polarity data from four sections of the uppermost Triassic and lower most Jurassic Moenave Formation, Utah and Arizona, USA, can be correlated to the marine successions at Saint Audrie's Bay (UK), Oyuklu, Turkey, and the Southern Alps, Italy, and to the nonmarine sections in Morocco, northern Africa, and the Newark Basin, eastern North America, all deposited across the Triassic-Jurassic boundary. Our proposed correlation provides a stratigraphic framework to tie Triassic-Jurassic sedimentation in the American Southwest to the marine UK, Turkey, and Italy sections, and to the Pangea rift history, including extrusive igneous rocks, preserved in Morocco and in the Newark Basin. The Moenave polarity record is characterized by mostly normal polarity, as is consistent with other polarity records across the Triassic-Jurassic boundary, and is interrupted by at least two well-defined reverse-polarity magnetozones. On the basis of available paleontologic information, we interpret the oldest welldefined, reverse-polarity magnetozone, M2r of the Moenave Formation, to correlate with SA5n.2r or SA5n.3r of the Saint Audrie's Bay record, H- of the Oyuklu record, BIT5n.Ir of the Italcementi Quarry record, the oldest reverse magnetozone in sedimentary rocks in Morocco, and with reverse magnetozone E23r of the Newark Basin. The youngest reverse magnetozone of the Moenave Formation, M3r, is correlated to the latest Triassic magnetozones SA5n.5r of the Saint Audrie's Bay record, J- of the Oyuklu record, and with the interval of reverse polarity in the 'intermediate unit' of the Morocco record. Magnetostratigraphic correlations and marine biostratigraphic information support placement of the Triassic-Jurassic boundary in the middle to upper Whitmore Point Member of the Moenave Formation, the Lias Group of the Saint Audrie's Bay section, the chert-rich limestone of the Oyuklu section, above the Zu Limestone in Italy, and in the central Atlantic magmatic province extrusive zone in the Morocco and the Newark records. doi: 10.1130/B30136.1

Pseudagnostus rugosus Ergaliev, 1980 is described from the Furongian Ctenopyge tumida Zone at Gisl6vshammar, Scania, southern Sweden. This is the first record of this distinctive agnostoid in Scandinavia. The species is known previously from Malyi Karatau, Kazakhstan, and northwestern Hunan and western Zhejiang, South China, and provides a newly recognized link between middle-upper Furongian successions in Baltica, Kazakhstan and South China. The occurrences of P. rugosus allow a correlation between the C. tumida Zone of Baltica, the lower Eolotagnostus scrobicularis-Jegorovaia Zone of Kazakhstan and the lower Lotagnostus americanus Zone of South China. Keywords: agnostoids, Pseudagnostus, correlation, biostratigraphy, Furongian, Sweden. doi:10.1017/S0016756810000282

The stratigraphic architecture of the James Ross Basin, NW Weddell Sea continental shelf, shows three major phases of deposition: preglacial, ice-sheet growth, and ice-sheet dominated. The preglacial phase shows stratigraphic sequences that are similar to low-latitude margins. During the ice-sheet growth phase, there is evidence for initial ice-sheet grounding in the southern part of the basin, which migrated in steps northward. Sediment supply was also high during tile ice-sheet growth phase. During the ice sheet--dominated phase, both north and south parts of the basin inherited all the classic features indicative of glacial strata: large glacial troughs hundreds of meters deep and tens of kilometers wide, truncation of sequences overlain by chaotic seismic facies and topped with coherent laminated reflections, and an oversteepened continental slope. The James Ross Basin strata are divided into five units (S5-S1). Each unit is characterized based upon seismic facies and stratigraphic architecture, and the age of each unit is inferred from a seismic stratigraphic age model. End-member strata (S5 and S1) were drilled and dated during SHALDRIL and help to constrain this age model. In total, 34 grounding events of the Antarctic Peninsula Ice Sheet (APIS) are recorded on the continental shelf. This is similar to the 31 grounding events imaged on the Pacific side of the peninsula. Ice grounding on the continental shelf is shown to have occurred as early as late middle Miocene to early late Miocene in the southern part of the basin. The ice sheet advanced northward to encompass the northern peninsula by late Miocene time. The seven oldest glacial unconformities are believed to predate all previously identified unconformities on the peninsula continental shelf. An expanded section of late Pliocene Pleistocene deposits shows a minimum of 10 grounding events; this record more closely matches the deep-sea oxygen isotope record than previous seismic studies of Antarctic margins have shown. doi: 10.1130/B26486.1

Ocean islands are subject to vertical movements through their lifetime and these movements' origins are poorly understood. Tracking island freeboard provides insight into the mechanisms that cause these movements. The Cape Verde archipelago is the result of hotspot volcanism ranging from 26 Ma to the present, and constitutes a structural pile that has preserved a record of the palaeo-positions of mean sea level. These palaeo-markers, both sedimentary and volcanic, are datable and can be used to track the island's history of vertical movements when used in conjunction with a eustatic curve. We have studied the volcanostratigraphy of Cape Verde and mapped the palaeo-marker positions and features, and we provide the sea-level height information that can be estimated through them. Evidence exists for differential uplift histories throughout the archipelago, with substantial uplift in some of the islands synchronous with volcanism. Other islands, in contrast, exhibit evidence for stability or complex uplift subsidence histories. Supplementary material: Detailed island geology information is available at http://www.geolsoc.org.uk/SUP18390. doi: 10.1144/0016-76492009-056.

The Palaeozoic--Mesozoic tectonic evolution of Central Asia, including the vast terrane collage that makes up Mongolia, has been a topic of considerable debate. The Oyut Ulaan Volcanic Group is a sequence of volcanic and sedimentary rocks in SE Mongolia that forms the southern part of the Devonian-Permian Saykhandulaan Inlier. Fieldwork traverses and mapping have established four distinct formations in the Oyut Ulaan Volcanic Group that record the nature of arc activity in part of the Central Asian Orogenic Belt during the Carboniferous. Physical volcanological and sedimentological characteristics of the four formations suggest three clear eruptive styles: (1) periodic andesite volcanism in an actively eroding arc setting that also contained large rivers and swamps; (2) highly effusive plateau andesite volcanism; (3) explosive rhyolitic effusion. Geochemical analyses of volcanic lithologies suggest that the group represents subduction-related, mature, continental arc volcanism. Geochemical results document an evolving magma system to which surface processes of the volcano-sedimentary model may be linked. Magma pulses and replenishments are identified from variations in chemostratigraphy. Newly obtained zircon ages from the volcanic succession fix its emplacement (eruption) at 323.0 [+ or -] 0.7 Ma (mid-Carboniferous or late Mississippian). A granite cobble from the lower part of the Oyut Ulaan Volcanic Group gives a U--Pb zircon age of 338.9 [+ or -] 0.4 Ma indicating that arc plutons were emplaced 10 Ma prior to the Oyut Ulaan volcanism and were eroded soon after. Our work provides timing constraints for final accretion and continental assembly in SE Mongolia, and also sheds light on the petrological development of a magmatic arc system within an evolving accretionary orogen. doi: 10.1144/0016-76492009-094.

The Late Triassic synrift succession of the Minas sub-basin (Bay of Fundy, Nova Scotia) includes a fluvio-alluvial fan-dominated unit (lower and middle Wolfville Formation), a transitional fluvio-playa unit (upper Wolfville Formation) and an upper playa-dominated package (Blomidon Formation). We describe the facies development in the 240 m thick upper Wolfville Formation, examine vertical facies stacking patterns and develop a depositional model for this succession. The unit comprises channelized and unconfined fluvial deposits interbedded with aeolian and playa sediments that grade upward into playa deposits. The succession comprises progradational and retrogradational fluvial packages and thin aggradational playa claystones. Comparison with 11 other Atlantic margin continental Triassic rift basins allows an assessment of the controls that govern rift basin development. The transition from fluvial to playa or lacustrine conditions occurs in all basins at different times. The lack of synchronicity indicates that global climate change was not a controlling factor. We suggest that the fluvial to lacustrine or playa transition was due to a decrease in source area relief related to a decline in regional tectonic activity, and that the basin was hydrologically closed throughout sedimentation. This tectonostratigraphic model may be appropriate for other Triassic basins developed along the Atlantic margin. doi: 10.1144/0016-76492009-092.

The Bohai Bay Basin, located on the eastern Asian margin, is the second largest oil-production basin in China. It contains numerous depressions and sags, among which Nanpu Sag has become particularly important because of significant oil discoveries in recent years. Geologically and tectonically, however, the rifting mechanism and geodynamic evolution of the basin remain uncertain. This paper uses detailed volcanic and stratigraphic records obtained through extensive drilling and sampling in Nanpu Sag to interpret tectono-stratigraphic sequences and discuss basin dynamic evolution and crust-mantle interactions of the Bohai Bay Basin. Nanpu Sag contains voluminous volcanic rocks of dominantly alkaline basalts. Drill core samples, well logs, and seismic profiles reveal three volcanic cycles between the Eocene and Miocene Epochs. These basalts were created during a transition from garnet- to spinel-peridotite. Five tectono-stratigraphic sequences produced by episodic continental rifting have been identified, each composed of a basal coarse clastic sequence, a lower volcanic sequence, a middle deep-water clastic sequence, and an upper infilling sequence. Tectonically, Nanpu Sag experienced four evolutionary phases. The first three corresponded to three rifting events revealed by cyclic volcanism and sedimentary depositional features. The fourth phase was marked by extreme thermal subsidence and prograding fluvial deposition fallowed by tectonic inversion. A diapiric upper-mantle upwelling model is proposed to explain the dynamics that controlled the multiple rifting processes, the cyclic volcanism, and the periodic tectonic evolution of Nanpu Sag and the greater Bohai Bay Basin. doi: 10.1130/B30041.1

Sedimentologic, stratigraphic, and structural data indicate that the Fountain Formation at Manitou Springs consists of three tectonostrarigraphic units, herein termed the lower, middle, and upper Fountain Formation. Both the lower and middle Fountain Formation were deposited in a fan-delta setting adjacent to the active ancestral Ute Pass fault. The lower is thin and predominantly characterized by deposirional stability as recorded by abundant well-developed, deeply rooted paleosols. The middle Fountain Formation reflects fan progradation and highland rejuvenation as a result of increased activity of the ancestral Ute Pass fault. This activity was likely the result of a basin-ward splay of the ancestral Ute Pass fault with reverse dip-slip motion as indicated by (1) exhumation of the lower Paleozoic Sawatch Formation and (2) fault-parallel folding. The upper Fountain Formation reflects deposition in a NW-SE-trending, braided-river system and appears to postdate movement on the ancestral Ute Pass fault. Lithostratigraphic correlation allows for a Latest Pennsylvanian-Early Permian age for the upper Fountain Formation, thus constraining cessation of the ancestral Ute Pass fault to Middle to Late Pennsylvanian time. The Fountain Formation was deposited within a NW-SE--oriented structural trough (i.e., Woodland Park trough) that separated the ancestral Front Range into a northern block (i.e., ancestral Front Range block) and a southern block (i.e., Ute Pass uplift). The Woodland Park trough was bounded on its southern margin by the ancestral Ute Pass fault, which was active throughout deposition of the lower two Fountain tectonostratigraphic units, during which time sediments were shed northward across the ancestral Ute Pass fault into a marine environment. By the rime of deposition of the upper Fountain Formation, movement on the ancestral Ute Pass fault had ceased or dramatically decreased. During this time, the Fountain Formation records predominantly axially oriented, braided-stream deposition. Comparison of the timing and kinematic history of the ancestral Ute Pass fault with other documented reverse and strike-slip faults of the ancestral Rocky Mountains suggests that: (1) cessation of faulting within the ancestral Rocky Mountains displays a slight east-to-west younging, but the crude age resolution of adjacent basin fill also allows for the possibility of relatively synchronous cessation of faulting, and (2) kinematics of all faults examined are consistent with a NE-SW--oriented maximum horizontal compressional stress field. These inferences contrast with the proposed Laurentian-Gondwanan diachronons closure models for the ancestral Rocky Mountains, which require rotation of the maximum horizontal stress orientation through time and pronounced east-to-west younging of faulting. Rotation of the horizontal stress field may be recorded in multistage, kinematic histories of faults, but multiple faults require study to assess this model. Age constraints on post-tectonic units of the ancestral Rocky Mountains, such as the upper Fountain Formation tectonostratigraphic unit defined herein, are poor and further refinement would greatly aid understanding of the kinematic riming and tectonic driving force of these ancient mountains. doi: 10.1130/B26554.1

Ocean-plate stratigraphy (basalt, chert, clastics) of the Balcreuchan Group in the Ballantrae complex is repeated by layer-parallel thrusts to form duplex structures south of Bennane Head, ~5 km north of Ballantrae. Five tuff beds, all in chert, have similar U-Pb zircon ages of ca. 470 [+ or -] 10 Ma. The geometrical polarity of the duplexes and the zircon ages provide new constraints on the tectonic evolution of the accretionary wedge of the Ballantrae complex. Northwestward thrusting of the duplexes suggests that subduction was from the northwest to the southeast, and this polarity at the leading edge of the main ophiolite body is consistent with the northward younging of the volcanic arc rocks of the Ballantrae complex. doi: 10.1130/B26329.1

A long-standing hypothesis links the increased prominence of meandering rivers in the middle Paleozoic to the colonization of terrestrial environments by vegetation. This hypothesis is tested using a data set of Cambrian to Devonian fluvial literature and field examination of key stratigraphic units. According to some researchers, Cambrian to mid-Silurian river systems were braided in planform, with a sharp increase in the abundance of meandering rivers during the Silurian--Devonian. Although meandering systems were largely identified on the basis of thick mudstones and organized channel deposits, the data set record of lateral accretion sets appears to be a robust proxy for the abundance of meandering river point bars. Lateral accretion is first recorded from Pridolian--Lochkovian strata, but is noted in nearly 40% of fluvial case studies by the Famennian. This trend matches the known record of rooted vegetation, suggesting that vegetation progressively stabilized river banks and promoted single-thread channels. However, the presence of Precambrian and extraterrestrial meandering systems indicates that vegetation is not essential for meandering, and the lack of evidence for Cambrian to Silurian (Ludlow) point bars is surprising. If originally present, they may largely have been destroyed by extreme floods, chute cut-offs in coarse-grained meandering systems, and eolian activity. doi: 10.1130/G30443

The collision between the Eurasian and Arabian plates along the 2400-km-long Bitlis-Zagros thrust zone isolated the Mediterranean from the Indian Ocean and has been linked to extension of the Aegean, rifting of the Red Sea, and the formation of the North and East Anatolian fault systems. However, the timing of the collision is poorly constrained, and estimates range from Late Cretaceous to late Miocene. Here, we report the first apatite fission-track (AFT) ages from the Bitlis-Zagros thrust zone. The AFT samples are distributed over the 450 km length of the Bitlis thrust zone in southeast Turkey and include metamorphic rocks and Eocene sandstones. Despite the disparate lithology and large distance, the AFT ages point consistently to exhumation between 18 and 13 Ma. The AFT ages, along with a critical appraisal of regional stratigraphy, indicate that the last oceanic lithosphere between the Arabian and Eurasian plates was consumed by the early Miocene (ca. 20 Ma). The results imply that Aegean extension predated the Arabia-Eurasia collision. doi: 10.1130/G30234.1

The late Wenlock Series (Homerian Stage) of the northern Midland Platform (central England) comprises silty mudstones and limestones of the upper part of the Coalbrookdale and overlying Much Wenlock Limestone formations. Based on outcrop studies and borehole data, the sequence stratigraphical interpretation developed for the inliers of the West Midlands is slightly revised, and extended to the stratotype sections along Wenlock Edge. A single third-order cycle of sea-level change is identified, punctuated by a regressive--transgressive episode associated with a higher-order glacioeustatic cycle, allowing the upper Wenlock Series of the area to be divided into two subsequences (A and B). Subsequence A and the early transgressive systems tract began with regression associated with the basal sequence boundary in late Cyrtograptus lundgreni Biozone times. This was followed by a period of slow transgression or stillstand, allowing shallower water carbonate environments to prograde. A minor phase of regression followed, resulting in the generation of the shallowest water deposits of both the Lower Quarried Limestone and Farley members (of the Much Wenlock Limestone and Coalbrookdale formations, respectively). The overlying Subsequence B and the late transgressive systems tract are marked by transgression and a period of rapid sea-level fluctuation and are likely contained within the Gothograptus nassa Biozone. A minor highstand is widely recognizable at this time. The rest of Subsequence B consists of an initial phase of weak progradation (highstand systems tract), followed by a marked regression (falling stage systems tract) culminating in an erosive upper sequence boundary at or close to the top of the Monograptus ludensis Biozone, but within the uppermost Much Wenlock Limestone Formation. Above Subsequence B is a marked transgression into the Lower Elton Formation and the Ludlow Series. Both late Wenlock lowstands and the succeeding flooding events have been recognized on other palaeocontinents, reflecting the eustatic nature of sea-level changes reported here. Keywords: Much Wenlock Limestone Formation, sequence stratigraphy, Silurian, Wenlock Series. doi: 10.1017/S0016756809990197

ABSTRACT Regional mapping and petrological studies have led to revision of the Cambrian-Ordovician stratigraphy in southwestern Nova Scotia. The Goldenville and Halifax formations have been elevated to groups, and formations [...]

The network of prior streams and palaeochannels common across the Riverine Plains of the Murray--Darling Basin act as conduits for the redistribution of water and soluble salts beneath the root-zone. To improve scientific understanding of these hydrological processes there is the need to better represent and map the connectivity and spatial extent of these physiographic and stratigraphic features. Groundbased electromagnetic (EM) instruments, which measure bulk soil electrical conductivity ([σ.sub.a]), have been used widely to map their areal distribution across the landscape. However, methods to resolve their location with depth have rarely been attempted. In this paper we employ a 1-D inversion algorithm with 2-D smoothness constraints to predict the true electrical conductivity (σ) at discrete depth increments using EM data. The EM data we use include the root-zone measuring EM38 and the deeper sensing EM34. We collected EM38 data in the vertical (EM38v) and horizontal (EM38h) dipole modes and EM34 data in the horizontal mode and coil spacing of 10, 20, and 40 m (respectively, EM34-10, EM34-20, and EM34-40). In order to compare and contrast the value of the various EM data we carried out multiple inversions using different combinations, which include: independent inversions of (i) EM38 (root-zone) and (ii) EM34 data (vadose-zone), and in combination using (iii) EM38v, EM38h, and EM34-10 (near-surface), and (iv) all 5 EM datasets (regolith) available. The general patterns of σ are shown to compare favourably with the known pedoderms, physiographic, and stratigraphic features and soil particle size fractions collected from calibration cores drilled across the lower Macquarie Valley study area. In general we find that the EM38 assists in resolving root-zone variability, specifically duplex soil profiles and physiographic features such as prior streams, while the use of the EM34 assists in resolving the stratigraphic nature of the vadose-zone and specifically the likely location of palaeochannels and subsurface anomalies that may indicate the location of good quality groundwater and/or clay aquitards. In this case, our potential to use σ to predict clay content is limited by the non-linearity of the cumulative functions. In order to improve on the non-linearity of our inversion we need to develop a full solution of the forward problem. Additional keywords: EM38, EM34, clay content, prior stream channel, palaeochannel, EM inversion., Introduction Across the Murray Darling Basin salt has accumulated naturally (primary salinity) in the regolith via cyclical deposits, aeolian processes, and connate stores. The redistribution of primary salts is attributed [...]

A 1284.87-m-long sediment core (AND-1B) from beneath the McMurdo sector of the Ross Ice Shelf provides the most complete single section record to date of fluctuations of the Antarctic Ice Sheets over the last 13 Ma. The core contains a succession of subglacial, glacimarine, and marine sediments that comprise ~58 depositional sequences of orbitalscale duration. These cycles are constrained by a chronology based on biostratigraphic, magnetostratigraphic, and [sup.40]Ar/[sup.39]Ar isotopic ages. Each sequence represents a record of a grounded ice-sheet advance and retreat cycle over the AND-1B drill site, and all sediments represent subglacial or marine deposystems with no subaerial exposure surfaces or terrestrial deposits. On the basis of characteristic facies within these sequences, and through comparison with sedimentation in modern glacial environments from various climatic and glacial settings, we identify three facies associations or sequence 'motifs' that are linked to major changes in ice-sheet volume, glacial thermal regime, and climate. Motif 1 is documented in the late Pleistocene and in the late Middle Miocene intervals of AND-1B, and it is dominated by diamictite of subglacial origin overlain by thin mudstones interpreted as ice-shelf deposits. Motif 1 sequences lack evidence of subglacial melt-water and represent glaciation under cold, 'polar'-type conditions. Motif 2 sequences were deposited during the Pliocene and early Pleistocene section of AND-1B and are characterized by subglacial diamictite overlain by a relatively thin proglacial-marine succession of mudstone-rich facies deposited during glacial retreat. Glacial minima are represented by diatom-bearing mudstone, and diatomite. Motif 2 represents glacial retreat and advance under a 'subpolar' to 'polar' style of glaciation that was warmer than present, but that had limited amounts of subglacial meltwater. Motif 3 consists of subglacial diamictite that grades upward into a 5- to 10-m-thick proglacial retreat succession of stratified diamictite, graded conglomerate and sandstone, graded sandstone, and/or rhythmically stratified mudstone. Thick mudstone intervals, rather than diatomite-dominated deposition during glacial minima, suggest increased input of meltwater from nearby terrestrial sources during glacial minima. Motif 3 represents Late Miocene 'subpolar'-style glaciation with significant volumes of glacially derived meltwater.

The Sulphur Mountain Formation in the Wapiti area is subdivided into the Phroso, Meosin Mountain (new), and Vega members, which collectively span much of the Lower Triassic. The Smithian conodont faunas are particularly well developed and form the basis of three partly new conodont zones and two new subzones: the lachrymiformis Zone, meeki Zone, and mosheri Zone, with the last subdivided into the phryna and milleri Subzones. An informal lowermost Smithian nepalensis interval is introduced, although it has yet to be found in the area. The Phroso Member is latest Griesbachian, Dienerian, and, in its uppermost part, Smithian, specifically the lachrymiformis and meeki zones: these are shown to be equivalent to the Euflemingites romunduri ammonoid Zone. The Meosin Mountain Member is assigned to the meeki Zone in its lower part and the phryna Subzone of the mosheri Zone in its upper part: at least, the upper part of the mosheri Zone is equivalent to the Anawasatchites tardus ammonoid Zone. The Mackenzie Dolomite Lentil is at least partly older than the Meosin Mountain Member, and age equivalence of subsurface turbidite units in the Montney Formation should not be assumed. The lowermost Vega Member is also assigned to the phryna Subzone, and higher parts of that member span both the milleri Subzone of the Smithian and the entire Spathian. The following new conodont taxa are described: Neogondolella? joanae, Novispathodus latiformis, Scythogondolella lachrymiformis, Sc. phryna, and Sc. rhomboidea; several other new species are kept in open nomenclature. La Formation de Sulphur Mountain dans le secteur de Wapiti est subdivisee en quatre membres : Phroso, Meosin, Mountain (nouveau) et Vega qui, ensemble, recouvrent une grande partie du Trias inferieur. Les faunes conodontes du Smithien sont particulierement bien developpees et forment la base de trois zones a conodontes partiellement nouvelles, soit la zone a lachrymiformis, la zone a meeki et la zone a mosheri; cette derniere zone est subdivisee en deux nouvelles sous-zones, la sous-zone a phryna et la sous-zone a milleri. Un intervalle informel, a nepalensis, le plus bas du Smithien, est introduit bien qu'il reste encore a le decouvrir dans le secteur. Le membre Phroso est dans le Griesbachien le plus tardif et dans le Dienerien; sa partie superieure est dans le Smithien, surtout dans les zones a lachrymiformis et a meeki : il est demontre que ces zones sont equivalentes a la zone ammonoide a Euflemingites romunduri. La partie inferieure du membre de Meosin Mountain est assignee a la zone a meeki et, dans sa partie superieure, a la sous-zone a phryna de la zone a mosheri : au moins la partie superieure de la zone a mosheri est l'equivalent a la zone ammonoide a Anawasatchites tardus. Le Mackenzie Dolomite Lentil est au moins partiellement plus age que le membre de Meosin Mountain et les equivalences en age des unites turbidites sous la surface dans la Formation de Montney ne devraient pas etre presumees. Le membre Vega le plus bas est aussi assigne a la sous-zone a phryna et les parties superieures de ce membre chevauchent la sous-zone a milleri du Smithien et tout le Spathien. Les nouveaux taxons de conodonte suivants sont decrits : Neogondolella? joanae, Novispathodus latiformis, Scythogondolella lachrymiformis, Sc. phryna et Sc. rhomboidea; plusieurs autres nouvelles especes sont gardees en nomenclature ouverte. [Traduit par la Redaction] doi: 1139/E09-051, Introduction The Lower Triassic Sulphur Mountain Formation in the Wapiti Lake area (Fig. 1) is well known for its exceptional fossil fish fauna (Schaeffer and Mangus 1976; Mutter and Neumann [...]

Our understanding of the geologic evolution of the Himalaya remains incomplete, particularly in regard to structural and geochronologic details of the Proterozoic-Paleozoic Lesser Himalayan Sequence. We conducted an integrated field mapping, geochronological study, and geochemical analysis of the Lesser Himalayan Sequence strata in the Kumaun and Garwhai Himalaya of NW India (78[degrees]00'-80[degrees]30'E). Structural observations reveal a systematic change in deformation styles from lower to higher structural levels in the Main Central Thrust footwall. In the south, and at lower structural levels, the Main Central Thrust footwall is characterized by parallel folding and sparse development of axial cleavage. Quartz microstructures indicate that deformation occurred at temperatures below 350[degrees]C. In contrast, in the north and at higher structural levels close to the Main Central Thrust, deformation is characterized by replacement of original bedding, the development of penetrative cleavage, and schistosity locally. Folds are tight, in places isoclinal and overturned. The corresponding quartz microstructures indicate that deformation occurred above 350[degrees]C. Dating of detrital zircons from Lesser Himalayan Sequence metasedimentary units, and igneous zircons from schistose gneisses throughout the Lesser Himalayan Sequence allow refinements to the stratigraphic framework. First, unlike what has been observed in western Nepal immediately west of our study area, U-Pb zircon dating suggests the absence of Paleoproterozoic strata in the Ramgarh Thrust hanging wall. This suggests that the thrust cuts upsection laterally along strike. Second, U-Pb detrital zircon dating suggests that metasedimentary strata in the Ramgarh Thrust hanging wall are correlative with basal units of the Outer Lesser Himalayan Sequence, removing the necessity that the Ramgarh Thrust hanging wall was allochthonous with respect to its footwall Lesser Himalayan Sequence units. Schistose gneisses with U-Pb ages of ca. 1850 Ma are older than Lesser Himalayan Sequence units in the area, suggesting that they are Lesser Himalayan Sequence basement. We conclude that the Ramgarh Thrust is an out-of-sequence thrust postdating a folding event in its footwall. The earlier proposal that Neoproterozoic-Cambrian Lesser Himalayan Sequence strata are the southern extension of the Tethyan Himalayan Sequence requires that the Tons Thrust, which separates the distal and proximal facies of the Lesser Himalayan Sequence, be a major, south-directed structure with a slip magnitude of >50-100 km.

A detailed study of the geochemical and isotopic characteristics of the volcanic rocks of the Hidden and Louis formations, which make up the hanging wall to the volcanogenic massive sulphide deposits at Flin Flon, Manitoba, was carried out on a stratigraphically controlled set of samples. The stratigraphy consists of the lowermost, dominantly basaltic, Hidden formation, and the overlying, dominantly basaltic, Louis formation. Of importance petrogenetically, is the 1920 unit a basaltic andesite with Nb/[Th.sub.mn] = 0.54-0.62, ζ[Nd.sub.(1.9Ga)] = +3.6-+5.9, ζ[Hf.sub.(1.9Ga)] = +8.5-+9.6, and [sup.204]Pb/[sup.206]Pb = 23.9. The basaltic flows that dominate the Hidden formation have Nb/[Th.sub.mn] = 0.16-0.29, ζ[Nd.sub.(1.9Ga)] = +1.7-+4.4, ζ[Hf.sub.(1.9Ga)] = +7.0-+11.8 and [sup.204]Pb/[sup.206]Pb = 16.9-18.6). The Carlisle Lake basaltic-andesite (top of Hidden formation) is characterized by Nb/[Th.sub.mn] = 0.16-0.14, and [sup.204]Pb/[sup.206]Pb = 21.4. The rhyodacitic Tower member (bottom of Louis formation) has Nb/[Th.sub.mn] = 0.23, ζ[Nd.sub.1.9Ga] = +4.6, ζ[Hf.sub.1.9Ga] = +9.3, and [sup.204]Pb/[sup.206]Pb = 22.2. The basaltic flows that dominate the Louis formation have Nb/[Th.sub.mn] = 0.18-0.25, ζ[Nd.sub.(1.9Ga)] = +3.6-+4.2, ζ[Hf.sub.(1.9Ga)] = +8.4-+11.3 and [sup.204]Pb/[sup.206]Pb = 17.9. The Hidden and Louis formations show dominantly transitional arc tholeiite signatures, with the 1920 unit having arc tholeiite characteristics. It is interpreted to have formed through extensive fractional crystallization of differentiated magmas at shallow levels in oceanic crust. Given the geological, geochemical, and isotopic characteristics of the Hidden and Louis formations, they are interpreted to represent subducted slab metasomatism with minor contamination from subducted sediments. Une etude detaillee des caracteristiques geochimiques et isotopiques des roches volcaniques des formations de Hidden et de Louis, lesquelles forment l'eponte superieure des gisements de sulfures volcanogenes massifs a Flin Flon, Manitoba, a ete effectuee sur un ensemble d'echantillons controles par la stratigraphie. La stratigraphie comprend, tout a la base, la formation de Hidden, principalement basaltique et la formation de Louis sus-jacente, principalement basaltique. L'unite 1920, une andesite basaltique, est importante d'un point de vue petrogenetique; elle possede les valeurs suivantes : Nb/[Th.sub.mn] = 0.,54-0,62, ζ[Nd.sub.(1.9Ga)] = +3,6 a +5,9, ζ[Hf.sub.(1.9Ga)] = +8,5 a +9,6, et [sup.204]Pb/[sup.206]Pb = 23.9. Les coulees basaltiques qui dominent la formation de Hidden ont les valeurs suivantes : Nb/[Th.sub.mn] = 0,16-0.29, ζ[Nd.sub.(1.9Ga)] = +1,7 a +4,4, ζ[Hf.sub.(1.9Ga)] = +7,0 a +11,8 et [sup.204]Pb/[sup.206]Pb = 16,9-18,6). L'andesite basaltique Carlisle Lake (sommet de la formation de Hidden) est caracterisee par Nb/[Th.sub.mn] = 0,16-0,14 et [sup.204]Pb/[sup.206]Pb = 21,4. Le membre Tower (bas de la formation de Louis) a les valeurs suivantes : Nb/[Th.sub.mn] = 0,23, ζ[Nd.sub.1.9Ga] = +4,6, ζ[Hf.sub.1.9Ga] = +9,3 et [sup.204]Pb/[sup.206]Pb = 22,2. Les coulees basaltiques qui dominent la formation de Louis ont les valeurs suivantes : Nb/[Th.sub.mn] = 0,18-0,25, ζ[Nd.sub.(1.9Ga)] = +3,6 a +4,2, ζ[Hf.sub.(1.9Ga)] = +8,4 a +11,3 et [sup.204]Pb/[sup.206]Pb = 17,9. Les formations de Hidden et de Louis presentent des signatures surtout d'arc tholeiitique de transition ou l'unite 1920 a des caracteristiques d'arc tholeiitique. Cette unite se serait formee par la cristallisation fractionnee a grande echelle de magmas differencies a de niveaux de faible profondeur dans la croute oceanique. E tant donne les caracte ristiques geologiques, geochimiques et isotopiques des formations de Hidden et de Louis, elles representeraient un metasomatisme de plaque subductee avec une contamination minime par les sediments subductes. [Traduit par la Redaction], Introduction Volcanogenic massive sulphide (VMS) deposits occur in extensional environments within a variety of tectonic settings, including oceanic, fore-arc, arc, back-arc, continental-margin, or continental settings (Franklin et al. 1981, 2005; [...]

The Lower Ordovician St. George Group of western Newfoundland consists mainly of shallow-marine-platform carbonates (~500 m thick). It is formed, from bottom to top, of the Watts Bight, Boat Harbour, Catoche, and Aguathuna formations. The top boundary of the group is marked by the regional St. George Unconformity. Outcrops and a few cores from western Newfoundland were sampled at high resolution and the extracted micritic materials were investigated for their petrographic and geochemical criteria to evaluate their degree of preservation. The δ[sup.13]C and δ[sup.18]O values of well-preserved micrite microsamples range from -4.2‰ to 0‰ (VPDB) and from -11.3‰ to -2.9‰ (VPDB), respectively. The δ[sup.13][C.sub.carb] profile of the St. George Group carbonates reveals several negative shifts, which vary between ~2‰ and 3‰ and are generally associated with unconformities-disconformities or thin shale interbeds, thus reflecting the effect of or link with significant sea-level changes. The St. George Unconformity is associated with a negative δ[sup.13][C.sub.carb] shift (~2‰) on the profile and correlated with major lowstand (around the end of Arenig) on the local sea-level reconstruction and also on those from the Baltic region and central Australia, thus suggesting that the St. George Group Unconformity might have likely had an eustatic component that contributed to the development-enhancement of the paleomargin. Other similar δ[sup.13][C.sub.carb] shifts have been recorded on the St. George profile, but it is hard to evaluate their global extension due to the low resolution of the documented global Lower Ordovician (Tremadoc--middle Arenig) δ[sup.13][C.sub.carb] profile. Le Groupe de St. George (Ordovicien inferieur) de fouest de Terre-Neuve comprend surtout des carbonates de plate-forme marine peu profonde (epaisseur ~500 m). De la base au sommet, il comprend les formations suivantes : Watts Bight, Boat Harbour, Catoche et Aguathuna. La limite superieure du groupe est marquee par la discordance regionale de St. George. Des affleurements et quelques carottes provenant de l'ouest de Terre-Neuve ont ete echantillonnes a haute resolution et les roches micritiques extractes ont ete etudiees pour leurs criteres petrographiques et geochimiques afin d'evaluer leur degre de preservation. Les valeurs δ[sup.13]C et δ[sup.18]O de micro-echantillons de micrites bien preservees variaient respectivement entre -4,2 [por millar] a 0 [por millar] << VPDB >> et entre -11,3 [por millar] a -2,9 [por millar] (VPDB). Le profil δ[sup.13][C.sub.carb] des carbonates du Groupe de St. George montre plusieurs changements a des valeurs negatives; ces changements varient entre ~2 [por millar] a 3 [por millar] et ils sont generalement associes a des discordances ou a de minces interlits de shale, refletant ainsi l'effet des changements importants de niveau de la mer ou ayant un lien avec ces changements. La discordance de St. George est associee a un changement negatif δ[sup.13][C.sub.carb] (~2 [por millar]) du profil et elle est correlee a un important bas niveau dans une reconstruction locale du niveau de la mer (vers la fin de l'Arenigien) ainsi qu'a des bas niveaux dans des regions de la Baltique et du centre de l'Australie, portant ainsi a croire que la discordance du Groupe de St. George avait une composante eustatique qui a contribue au developpement--rehaussement de la paleobordure. [Traduit par la Redaction], Introduction The stable isotope signatures encrypted in preserved marine carbonates have been successfully utilized to understand the evolution of the Earth's system and correlation of sedimentary sequences from different depositional [...]

Carbon-isotope stratigraphy is a useful tool for stratigraphic correlation, especially for strata deposited during major perturbations of the carbon cycle that affected the marine, terrestrial and atmospheric reservoirs. For the Triassic--Jurassic boundary, effectively defined by a first-order mass extinction, major fluctuations in carbon-isotope values have been well documented, but these datasets have generally been derived from bulk-rock samples. Hence, the extent to which features of the isotopic curve reflect diagenetic alteration or changing proportions of constituent materials is unconstrained. Here, carbon- and oxygen-isotope data are presented from well-preserved oyster shells (Liostrea) comprising low-magnesium calcite, a mineral species relatively resistant to diagenetic alteration. Samples were obtained from Lavernock Point, Glamorgan, Wales, a coastal section close to a candidate stratotype for the base of the Jurassic at St Audrie's Bay, Somerset, England. The carbon-isotope signature from St Audrie's Bay, previously defined on the basis of analysis of bulk organic matter, is confirmed by our new data. Major features are (1) the upper part of an 'initial' negative isotope excursion in the lowest part of the section, followed by (2) a pronounced positive excursion, and (3) an extended 'main' negative isotope excursion in the highest part of the section. The data confirm that the carbon-isotope stratigraphy previously documented from bulk organic matter in SW England records the chemical composition of the contemporaneous seawater. Bulk carbonates sampled over the same interval near Lyme Regis, England, show similar trends to those from oyster calcite in the lower part of the study section, but there are more [sup.13]C-depleted values up-section. These lower values probably result from an admixture of primary and diagenetic carbonate. Palaeotemperatures calculated from oxygen-isotope values from Lavemock Point oyster shells are relatively cool at the beginning of the positive carbon-isotope excursion, and increased by up to 10[degrees]C during the main negative carbon-isotope excursion. The new results are compatible with the view that positive carbon-isotope excursions correspond to times of low atmospheric carbon dioxide content, whereas negative carbon-isotope excursions correspond to times of high atmospheric carbon dioxide content, as is also found to be the case during the Early Jurassic (Toarcian) Oceanic Anoxic Event. The Mg/Ca and Sr/Ca ratios and [delta][sup.18]O of investigated Liostrea hisingeri show no correlation, supporting data from modern bivalves that indicate that incorporation of Mg and Sr is controlled mainly by factors other than temperature.