Search

Enigmatic successions of deep-water strata referred to as the Nesmith beds and Grant Land Formation comprise the exposed base of the Franklinian passive margin sequence in northern Ellesmere Island, Nunavut. To test stratigraphic correlations with Ediacaran to Cambrian shallow-water strata of the Franklinian platform that are inferred by regional basin models, >500 detrital zircons from the Nesmith beds and Grant Land Formation were analyzed for sediment provenance analysis using laser ablation (LA-ICP-MS) and ion-microprobe (SIMS) methods. Samples of the Nesmith beds and Grant Land Formation are characterized by 1000-1300,1600-2000, and 2500-2800 Ma detrital zircon age distributions and indicate provenance from rock assemblages of the Laurentian craton. In combination with regional stratigraphic constraints, these data support an Ediacaran to Cambrian paleodrainage model that features the Nesmith beds and Grant Land Formation as the offshore marine parts of a north- to northeast-directed depositional network. Proposed stratigraphic correlations between the Nesmith beds and Ediacaran platformal units of northern Greenland are consistent with the new detrital zircon results. Cambrian stratigraphic correlations within northern Ellesmere Island are permissive, but require further investigation because the Grant Land Formation provenance signatures agree with a third-order sedimentary system that has been homogenized by longshore current or gravity-flow processes, whereas coeval shallow-water strata yield a restricted range of detrital zircon ages and imply sources from local drainage areas or underlying rock units. The detrital zircon signatures of the Franklinian passive margin resemble those for the Cordilleran and Appalachian passive margins of Laurentia, which demonstrates the widespread recycling of North American rock assemblages after late Neoproterozoic continental rifting and breakup of supercontinent Rodinia. Des suites non conventionnelles de strates d'eau profonde, connues sous le nom de lits Nesmith et Formation de Grant Land, comprennent la base affleurant de la sequence de bordure passive franklinienne dans le nord de l'lle d'Ellesmere, au Nunavut. Dans le but de verifier les correlations stratigraphiques avec des strates ediacariennes et cambriennes d'eau peu profonde de la plateforme franklinienne, inferees par une modelisation des bassins regionaux, plus de 500 zircons detritiques des lits Nesmith et de la Formation de Grant Land ont ete analyses pour la provenance des sediments; les methodes utilisees comprennent l'ablation laser-spectrometrie de masse a source a plasma inductif (LA-ICP-MS) et les microanalyses ioniques (SIMS). Des echantillons des lits Nesmith et de la Formation de Grant Land sont caracterises par des distributions d'age de zircons detritiques de 1000-1300,1600-2000 et 2500-2800 Ma; ils proviendraient d'assemblages de roches du craton laurentien. Combinees aux contraintes stratigraphiques regionales, ces donnees supportent un modele de paleodrainage, de l'Ediacarien au Cambrien, lequel montre les lits Nesmith et la Formation de Grand comme etant les parties marines au large d'un reseau de deposition, de direction nord a nord-est. Les correlations proposees entre les lits Nesmith et les unites ediacariennes de plateforme du nord du Groenland concordent avec les nouveaux resultats sur les zircons detritiques. Les correlations stratigraphiques cambriennes a l'interieur de l'lle d'Ellesmere sont facultatives, mais elles demandent plus d'etudes puisque les signatures de provenance de la Formation de Grant Land concordent avec un systeme sedimentaire de troisieme ordre qui a ete homogeneise par les courants littoraux ou les processus d'ecoulement gravitaire, alors que les strates contemporaines d'eau peu profonde ont donne une plage restreinte d'ages des zircons detritiques, impliquant une provenance de drainage local ou d'unites rocheuses sous-jacentes. Les signatures des zircons detritiques de la bordure passive franklinienne ressemblent a celles des bordures passives de la Cordillere et des Appalaches de la Laurentie, ce qui demontre le recyclage etendu des assemblages de roches de l'Amerique du Nord, apres la distension continentale au Neoproterozoique et le fractionnement du supercontinent Rodina. [Traduit par la Redaction], Introduction The Franklinian basin of the Canadian Arctic Islands and northern Greenland comprises an integral part of the Franklinian passive margin sequence that was deposited along the northern edge of [...]

Northeastern Melville Peninsula, Nunavut, Canada, preserves the stratigraphic record of the northwestern margin of the Foxe Basin. The Ordovician sequence on the peninsula includes the Lower Ordovician Ship Point Formation and Upper Ordovician Frobisher Bay, Amadjuak, Akpatok, and Foster Bay formations. Their biostratigraphic ages and correlations are poorly understood; in particular it is unclear whether the organic-rich 'Boas River Formation' exists on the peninsula. Following extensive sampling of these stratigraphic units, studies of numerous conodont elements from both outcrops and rubble at about 60 localities have established five conodont assemblages through the five lithostratigraphic units on the peninsula. Oepikodus communis--Jumudontus gananda Assemblage in the Ship Point Formation is correlated to the Reutterodus andinus Zone in the uppermost Ibexian, Lower Ordovician. The other four assemblages from the Upper Ordovician are as follows: Appalachignathus delicatulus--Polyplacognathus ramosus--Belodina confluens in the Frobisher Bay Formation correlated to lower B. confluens Zone in the upper Chatfieldian; Belodina confluens--Periodon grandis in the Amadjuak Formation to the upper B. confluens, Oulodus velicuspis, O. robustus, and lower Aphelognathus grandis zones from Edenian to lowest Richmondian; Amorphognathus ordovicicus--Plegagnathus and Rhipidognathus symmetricus--Aphelognathus cf. A. divergens in the Akpatok and Foster Bay formations to the lower and upper Richmondian. The biostratigraphy is combined with geographical information systems (GIS) and Google Earth technologies in estimating the thickness of Paleozoic strata, which reduces the likelihood of 'Boas River Formation' existing on Melville Peninsula to minimum. Le profil stratigraphique de la marge nord-ouest du bassin de Foxe est preserve dans le nord-est de la peninsule de Melville, au Nunavut (Canada). La succession ordovicienne de la peninsule comprend la Formation de Ship Point de l'Ordovicien inferieur, et les Formation de Frobisher Bay, Amadjuak, Akpatok et Foster Bay de l'Ordovicien superieur. Les ages et correlations biostratigraphiques de cette succession sont mal compris, notamment en ce qui concerne l'existence ou non dans la peninsule de la << Formation de Boas River >>, riche en matiere organique. Apres un vaste echantillonnage de ces unites stratigraphiques, des etudes de nombreux elements de conodontes provenant d'affleurements et de blocs en une soixantaine de localites ont permis de definir cinq assemblages de conodontes dans les cinq unites lithostratigraphiques de la peninsules. L'assemblage a Oepikodus communis--Jumudontus gananda de la Formation de Ship Point est correle a la zone a Reutterodus andinus du sommet de l'Ibexien (Ordovicien inferieur). Les quatre autres assemblages de l'Ordovicien superieur sont l'assemblage a Appalachignathus delicatulus Polyplacognathus ramosus--Belodina confluens dans la Formation de Frobisher Bay correle a la zone a B. confluens inferieure du Chatfieldien superieur, l'assemblage a Belodina confluens--Periodon grandis dans la Formation d'Amadjuak correle aux zones a B. confluens superieure, Oulodus velicuspis, O. robustus et Aphelognathus grandis inferieure de l'Edenien a la base du Richmondien, l'assemblage a Amorphognathus ordovicicus--Plegagnathus et Rhipidognathus symmetricus--Aphelognathus cf. A. divergens dans les Formations d'Akpatok et de Foster Bay correle au Richmondien inferieur et superieur. La biostratigraphie jumelee a des methodes reposant sur les SIG et Google Earth est utilisee pour estimer l'epaisseur des strates paleozoiques. Les resultats reduisent au minimum la probabilite de l'existence de la << Formation de Boas River >> dans la peninsule de Melville. [Traduit par la Redaction], Introduction The depositional and tectonic term, Foxe Basin, was first introduced by Christie (1972) to apply to a discontinuous belt of Lower Paleozoic outcrops extending from central northwestern to south-central [...]

The global correlation standards now agreed for the Ordovician and Silurian systems, and partly so for the Cambrian System, are summarized. Correlation of the international series and stages with the traditional and revised British series and stages is reviewed, as well as with those in North America (Laurentia). Keywords: Cambrian, Ordovician, Silurian, correlation, British Isles. doi: 10.1017/S0016756809990562

The Global Stratotype Section and Point (GSSP) for Stage 2 of the Ordovician System, now the Floian Stage and approximately equivalent to the lower and middle Arenig of England and Wales, is defined by the first appearance datum (FAD) of the graptolite Tetragraptus approximatus in the Diabasbrottet Quarry section at Mount Hunneberg, Sweden. One of the issues this raises is how to correlate the base of Stage 2 at the GSSP with areas and successions that do not contain a correlative graptolite fauna. The distinctive Cymatiogalea messaoudensis--Stelliferidium trifidum acritarch assemblage is present in the upper Tremadocian Araneograptus murrayi Graptolite Biozone of NW England and ranges across the Tremadocian--Stage 2 boundary there (the Tremadoc--Arenig boundary of Anglo-Welsh nomenclature). It also occurs widely at other high southern Ordovician palaeolatitudes around the margin of Gondwana, being reported from Ireland, Wales, the Isle of Man, Belgium, Germany, Spain and Turkey, and may also be present in Bohemia and Argentina (Eastern Cordillera). It therefore has the potential to contribute towards the recognition and correlation of the base of Stage 2 in those areas. Of particular interest are the First Appearance Datums of various taxa within the stratigraphical range of the messaoudensis--trifidum assemblage, notably that of Aureotesta clathrata simplex, which is considered to be close to the base of Stage 2 in NW England. Elements of the messaoudensis--trifidum assemblage also occur in Baltica, the palaeoplate on which the GSSP for the base of Stage 2 is located. However, many of the taxa used to subdivide the messaoudensis--trifidum assemblage around Gondwana have not been recorded from Baltica and may be restricted palaeobiogeographically to the Gondwanan margin. Furthermore, acritarch microfloras have not been reported from the Diabasbrottet Quarry section itself, and there are hiatuses across the base of Stage 2 in the two sections from Baltica considered in this paper. Hence, direct correlation of the base of Stage 2 between the GSSP and other sections using acritarchs is not yet possible. Nevertheless, some taxa, for example the genera Peteinosphaeridium and Rhopaliophora, are shown to have FADs at similar stratigraphical levels in the late Tremadocian Stage of both Baltica and Gondwana, and therefore have the potential to correlate time slices in the late Tremadocian Stage between palaeoplates. Keywords: acritarchs, stratigraphic correlation, Lower Ordovician, Tremadocian--Floian boundary.

The development of the flow field produced by concentric jets used in the blown-film manufacturing process was studied experimentally using hot wire anemometry. It was found that the inner jet was entrained into the outer jet before the outer jet attached to the wall The inner shear layer of the outer jet attached to the surface 3H to 5H downstream of the jet exit, and the outside shear layer of the outer jet attaches to the surface further downstream of the jet exit. The distribution and spectra of the fluctuating wall pressure was measured using microphones. The pressure fluctuations were largest where the outer jet attached to the surface, and had characteristic frequencies of 100 to 900 Hz. Measurements of two-point and two-time correlation of the fluctuating pressure were used to characterize the development of the large-scale structures that caused these pressure fluctuations. It was found that the structures were convected along the surface at 0.45 to 0.7 of the outer jet velocity for different ratios between inner and outer jet velocities. The convection velocity of the large scale structures in the region farther than 10H downstream of the jet exit was determined by the upper jet velocity. [DOI: 10.1115/1.1989367]

We have investigated the sequence stratigraphy of two widely separated marine Cenomanian successions in southeast India and northwest Europe, and used high-resolution ammonite biostratigraphy to demonstrate that sea-level changes are globally synchronous and therefore must be eustatically controlled. Sequence-scale sea-level changes in the Cenomanian were driven by the long eccentricity cycle (400 k.y.) in the Milankovitch band. We hypothesize that, during pre-Quaternary time, the third-order sequences of Vail and Haq are essentially a sediment response to sea-level changes driven by the 400 k.y. cycle. Construction of a relative sea-level curve for the marginal marine succession in India demonstrates that the short-term sea-level changes are rapid (10-100 m/m.y.) and have a magnitude of 2-20 m. Glacioeustasy is a possible but unproven driving mechanism. Keywords: sequence stratigraphy, ammonite biostratigraphy, eustasy, Cenomanian (Cretaceous), Europe, India.

Four major questions are addressed in this review article to deal with ignorance about organic evolution and what should be done in the future. Addressed are the relationship of genotype and phenotype, the temporal framework of evolution and the molecular clocks that show history of life, though seriously at odds with the fossil record, data from molecular biology and insights into mechanisms of macroevolution, and constructing phylogenies, which is central to the evolutionary enterprise, but with rival schemes often contradicting one another. The fundamental question is perhaps explaining the great diversity of life vs the great similarity in molecular architecture.

The Silurian succession of North Galway is relatively well constrained in terms of environmental analysis and, in its lower half, palaeontologically. The initiation of a late Llandovery marine transgression can be demonstrated over fluviatile red sandstones. The deposition of shallow-water conglomerates at the base of a turbidite sequence within the succession indicates the long-lived presence of a channel system that was probably fault controlled. The back-stripping method allows a subsidence curve to be constructed for this succession. It demonstrates an initial period of rapid rift-related subsidence followed by a short-lived hiatus that may be due to the cessation of subduction in this part of the Caledonides. A comparison of the Galway subsidence curve with that of the Silurian succession at Girvan in Scotland shows strong, but diachronous, similarities. This tends to support an earlier suggestion that they formed part of a single but partitioned basin throughout most of the Silurian period. Although the eustatic fall in sea level at the Llandovery-Wenlock boundary can be recognized, the influence of tectonic regime and sedimentation rates were the controlling factors in determining relative sea levels.

This study of ancient desert deposits (Permian Brodick Beds) tests the possibility that cyclicity in these interbedded aeolian, fluvial and lacustrine deposits was orbitally controlled. The 740 m thick succession of desert deposits forms one sequence which can be divided into three genetic units. A major deflation surface forms the basal sequence boundary and represents a drop in base-level (groundwater table). On top of the sequence boundary are rather uniform aeolian dune and sand-sheet sediments (Unit 1) formed in an erg during low base-level with increasing rates of base-level rise. They are followed by interbedded aeolian dune, aeolian sand-sheet and flood-reworked aeolian sediments (Unit 2) representing erg margin deposits formed during increasing rates of base-level rise. The uppermost part of the sequence is composed of gravel sheets (Unit 3) representing alluvial fan deposition during a high base-level with decreasing rates of base-level rise. The succession is cyclic, and spectral analysis of sedimentary and geochemical parameters reveal cycles with a thickness of 25.7-29.3 m, 34.5 m, and 64.5 m, and fieldwork reveals cycles of 155 m and 675 m. These sedimentary cycles are thought to reflect climatic oscillations. The lack of detailed time control makes it difficult to link these climatic fluctuations to orbital cycles, although the detected cyclicity matches well with Milankovitch theory. Keywords: Arran, Upper Permian, cyclic processes, sequence stratigraphy, deserts.

The first systematic test for a predictive relationship between organic carbon content and stratigraphic hierarchy in a deep-water slope to basin-floor deposit was performed. The studied section includes the Pipeline Shale, the Brushy Canyon Formation, and the lower part of the Cherry Canyon Formation of the Delaware Mountain Group, West Texas. This interval represents one large-scale, 3rd-order genetic sequence within which 4th- and 5th-order stratigraphic cycles are recognized. Samples of fine-grained facies throughout the section were collected from outcrop and analyzed for organic carbon content and hydrogen index. Degree of pyritization was also determined for a subset of the samples. The results indicate that organic enrichment is closely correlated to the stratigraphic hierarchy at the 3rd-, 4th-, and 5th-order levels. The data suggest that quantity and quality of preserved organic matter are controlled by changes in bulk sedimentation rate (dilution vs. condensation), which affect organic matter inputs to the sediment, as well as the balance between (1) burial and preservation of organic matter and (2) its degradation on the sea floor during times of sediment starvation.

We present a new mean-high-water curve for Hammock River marsh, Clinton, Connecticut, obtained by improving the age model for an existing record of relative marsh elevation based on foraminiferal analysis of a 1.8-m-long peat core. Unlike the earlier curve, the new curve confirms trend changes in mean-high-water rise during the past 1400 yr as noted for salt marshes 15 km farther west, suggesting a regional cause. These trend changes and century-scale mean-high-water variations in the Clinton record correlate positively with large-scale regional variations in sea-surface and summer-air temperature, indicating a link between sea level and the climate-ocean system. On the basis of the Clinton mean-high-water curve, we conclude that real sea level oscillated centimeters to decimeters on a century time scale over the past 1400 yr, was 25 [+ or -] 25 cm higher ca. A.D. 1050 (Medieval Warm Period) than ca. A.D. 1650 (Little Ice Age), and rose at a mean rate of [approximately]1 min. [yr.sup.-1] over the past 350 yr; there was little or no rise during the cool 1800s.

Recent radiometric dating of carbonates and banded iron-formations on the Kaapvaal Craton, southern Africa, has suggested that late Archaean and Palaeoproterozoic carbonate sedimentation was diachronous across the craton. We present new SHRIMP U-Pb zircon ages of 2583 [+ or -] 5 Ma and 2588 [+ or -] 7 Ma for two samples of a tuff bed, 320 km apart in the upper Oak Tree Formation, Transvaal Supergroup. These ages, in conjunction with published data, support previously established sequence stratigraphic correlations that show the temporal equivalence of late Archaean carbonates in the region. A review of the sequence stratigraphy and geochronology of the Mount Bruce Megasequence Set on the Pilbara Craton, Western Australia, and the newly named Highveld Megasequence Set on the Kaapvaal Craton, indicates a remarkably similar geohistory. Both cratons are characterized by a divergent megacycle (Hamersley Range and Vaal Megasequences) followed by a convergent megacycle (Chichester Range and Drakensberg Megasequences). Our data show that the megasequence boundary is marked by drowning of both cratons at approximately the same time (c. 2590 Ma), which permits more meaningful geotectonic correlations between them. Keywords: Kaapvaal Craton, Pilbara Craton, SHRIMP, zircon, correlation.

The Domeyko Basin of northern Chile records Late Triassic to Early Cretaceous mixed carbonate and siliciclastic marine deposition along the western margin of Gondwana. Sequence stratigraphical analysis has identified five long-term sequences of 11-17 Ma duration. Comparison of the relative sea-level fluctuations interpreted from the Domeyko Basin succession with those documented from other similar-aged South American marginal basins and northern hemisphere basins allows the distinction of regional from global events. Relative sea-level fall in the Early Pliensbachian, Early Aalenian and Early Valanginian, and rises in the Early Hettangian, Early and Late Toarcian, Early and Late Bajocian, Late Bathonian and Early Oxfordian of the Domeyko Basin appear time-equivalent to similar events in other southern and northern hemisphere basins and are thus interpreted to be products of global sea-level cycles. Long-term relative sea-level falls in the Early Bathonian, Late Oxfordian, Early Valanginian and rise in the Late Kimmeridgian are interpreted to be tectonically driven, continental-scale changes in sediment-accommodation space. The Domeyko Basin succession thus appears to have been dominantly controlled by global sea-level fluctuations during the Early to Mid-Jurassic and by continental-scale (but not global) fluctuations during the Mid-Jurassic to Mid-Cretaceous, interpreted to have been driven by the fragmentation of Gondwana. Keywords: carbonates, siliciclastics, sequence stratigraphy, Jurassic, transgressions, regressions.

New data are presented that demonstrate the syn-tectonic intrusion of a suite of mafic and ultramafic magmas into the Connemara Dalradian. Magma was intruded during the local D2 episode but immediately prior to the onset of D3. Both deformation episodes affect the gabbros, forming two distinct groups of fabrics formed at different stages during the history of the intrusion. Applying thermal considerations to this history suggest that any gap in time between the formation of these fabrics was Keywords: Caledonides, Dalradian, gabbros, thermal metamorphism, diachronism.

Foreland basins are created by superimposed mechanisms that flex the lithosphere. In addition to static loads, dynamic loading below the basin by viscous mantle corner flow above a subducting plate may cause long-wavelength subsidence. It is proposed that the interaction of the static and dynamic forces is responsible for the formation and preservation of recently recognized 'reciprocal stratigraphies' in retro-foreland regions above subducting slabs. Reciprocal stratigraphies refer to a correlative succession of strata characterized by contrasting stacking patterns that reflect opposite base-level changes between proximal and distal settings. The same interactions may also modify the stratigraphy of the flexural peripheral bulge and mask its presence. An example from the Late Cretaceous of the Western Interior basin, Canada, illustrates the concepts.

The maximum flooding event within a depositional sequence is an important datum for correlation because it represents a virtually synchronous horizon. This event is typically recognized by a distinctive physical surface and/or a significant change in microfossil assemblages (relative fossil abundance peaks) in siliciclastic deposits from shoreline to continental slope environments in a passive margin setting. Recognition of maximum flooding events in mixed siliciclastic-carbonate sediments is more complicated because the entire section usually represents deposition in continental shelf environments with varying rates of biologic and carbonate productivity versus siliciclastic influx. Hence, this event cannot be consistently identified simply by relative fossil abundance peaks. Factors such as siliciclastic input, carbonate productivity, sediment accumulation rates, and paleoenvironmental conditions dramatically affect the relative abundances of microfossils. Failure to recognize these complications can lead to a sequence stratigraphic interpretation that substantially overestimates the number of depositional sequences of 1 to 10 m.y. duration.

A model of the stratigraphy of sequences in coal, based on a subsurface case study of the coal-bearing Lower Cretaceous Mannville Group of Canada, posits basinward progressive splitting patterns of thick, regionally extensive paralic coal seams. Successive splits bounded by transgressive-regressive coal-seam couplets are interpreted to be fourth-order sequences produced in single base-level cycles. Stacked in a progradational pattern, these fourth-order sequences in turn form third-order sequences. Thick, regional seams form on top of a prograding platform by amalgamation of several fourth-order sequences. Vertical profiles of coal properties (geochemistry, petrology, and palynology) in the lower and upper leaves of a split seam which constitute a transgressive-regressive couplet would yield characteristic signatures revealing their transgressive and regressive nature, respectively.

Although identifying unequivocally the cause of transgressions and regressions from the rock record can be difficult, we can place limits on the possible combinations of sediment supply, subsidence, and sea level that could generate an observed stratigraphic sequence. Using simple geometric models that estimate maximum rates of change in the three controlling variables, and combining these with other limits derived from field observations, we can plot a solution set to define the most likely range of variations in these three primary controls on shoreline migration. This approach shows the amount each controlling factor must change alone, or in concert, to account for the stratigraphy. These quantitative values can be used to decide what is geologically reasonable and what is not. Although a unique solution may not be available, we can calculate the required parameters for the observed shoreline migrations, which provide a basis for informed interpretations.

Acritarch specimens were found on the clay horizon above the unconformity between the Lower Cambrian Wrekin Quartzite and the Ercall Granophyre. The specimens were dated and used in relation to age determination of the granophyre intrusion and the unconformity. Stratigraphic findings and age determination have shown that the intrusion occurred 560 plus or minus one Ma. However the Cambrian Unconformity is younger than 533 plus or minus 13 Ma.

Uranium-lead ages from an ion probe were taken for zircons from the ore-bearing Noril'sk I intrusion that is comagmatic with, and intrusive to, the Siberian Traps. These values match, within an experimental error of ± 4 million years, the dates for zircons extracted from a tuff at the Permian-Triassic (P-Tr) boundary. The results are consistent with the hypothesis that the P-Tr extinction was caused by the Siberian basaltic flood volcanism. It is likely that the eruption of these magmas was accompanied by the injection of large amounts of sulfur dioxide into the upper atmosphere, which may have led to global cooling and to expansion of the polar ice cap. The P-Tr extinction event may have been caused by a combination of acid rain and global cooling as well as rapid and extreme changes in sea level resulting from expansion of the polar ice cap., It has recently been suggested that flood volcanism is produced by melting of the head of starting plumes that originate at the core-mantle boundary and grow by entrainment as they [...]

The cyclic pattern of deposition in the Horquilla Limestone of southeastern Arizona resulted from glacio-eustatic sea-level fluctuations with periodicities within the Milankovitch band. The depositional surface fluctuated from above sea level to below the depth of autochthonous carbonate production. By means of characteristics of the cycles, correlations can be established not only between sections in the Pedregosa basin of southeastern Arizona, but also to the midcontinent of the United States. These correlations exceed the resolution of biostratigraphy and distinguish the eustatic component of relative sea-level fluctuations in widely spaced basins with different depositional settings., Cyclostratigraphic analysis is used to determine the pattern and causes of Horquilla limestone deposition in southeastern Arizona. Data from the Gunnison Hills and the Dry Canyon section of the Whetstone Mountains were used for the correlations, which had better resolutions than biostratigraphy. Platform carbonates best evince eustasy and are sensitive to base-level changes. Horquilla Limestone cyclicity is predominantly eustatic because of the tectonic stability of the Pedregosa shelf.

We have evaluated the Neogene stratigraphic succession beneath the continental shelf off New Jersey using high-quality seismic and well data to (1) construct geologic cross sections that relate seismic geometries to lithofacies in a prograding, tectonically quiescent setting; (2) apply a sequence-stratigraphic approach to subdivide the stratigraphic section and relate the characteristics of the depositional observed sequences to the published Exxon model; and (3) determine the resolution of the available biostratigraphy in the correlation of the offshore New Jersey depositional sequences to the published eustatic cycle chart. In the offshore New Jersey area, the well-developed progradational geometries in the Neogene section, the high-quality seismic data, and the relatively abundant lithologic information from wells allow us to use the results of this study to predict lithofacies distribution in similar, but less geologically constrained, settings. Seismic sequence analysis and interpretation of stratal stacking patterns in well logs indicate that the observed depositional sequences can be subdivided into lowstand (lowstand fan and lowstand wedge) and highstand systems tracts. Lowstand fans of lowstand systems tracts are characterized by thick, aggradational sandstones that exhibit a 'blocky' to fining-upward well-log signature. Lowstand wedges of lowstand systems tracts generally display upward-coarsening, but dominantly shale-prone, lithofacies. Transgressive systems tracts, if present, are very thin. Highstand systems tracts consist of strata that shoal from prodelta mudstone to thick, relatively homogeneous sandstone. Sandstone beds occur in association with two distinct seismic facies. The first type compose the topset and toplapping beds of prograding depositional systems, typically highstand systems tracts. These sandstone beds thicken to as much as 150 m towards the depocenters of each sequence and thin along strike, away from the depocenters. The second type of sandstone is present at the toes of depositional slopes, where it onlaps against prograding deltaic wedges. The observed geometry and lithofacies distribution of the Neogene depositional sequences are compared to the 'standard' Exxon sequence stratigraphic model. Depositional sequences recognized in this study are characterized by similar overall stacking patterns within component systems tracts; however, the New Jersey sequences are different in several ways. These differences include the lack of type-2 unconformities, an absence of leveed channel deposits within lowstand wedges, very poorly developed transgressive systems tracts, and sandstone-rich, highly regressive highstand systems tracts. These differences are explained in terms of the limited Neogene accommodation on the New Jersey shelf that resulted from slow subsidence rates and a second-order Miocene eustatic fall. Paleontologic data bracket the ages of the individual sequences but are not detailed enough at present to correlate precisely to the time scale and inferred global sea-level records. Based on the available biostratigraphy, however, Neogene depositional sequences from offshore New Jersey have a cyclicity consistent with interpreted third-order eustatic fluctuations on the global cycle chart.

U-pb baddeleyite ages of 1087 [+ or -]3 and 1069 [+ or -]3 Ma for two diabase silis that intrude the Crystal Spring Formation of the Pahrump Group, southeastern Cahfornia, provide a minimum estimate for the depositional age of the Crystal Spring Formation. The new ages highlight the potential range in deposition ages for the Pahrump Group, from [is greater than or equal to]1087 Ma to possibly as young as 600 Ma for Kingston Peak glaciogenic sediments. Consequently, there probably are significant disconformities within the Pahrump Group that separate unrelated, tectonically distinct episodes of basin subsidence. The Crystal Spring and Beck Spring Formations are considered to be platform-cover rocks preserved as a result of block faulting during deposition of the upper Kingston Peak Formation. The age of the Pahrump sills is in excellent agreement with the age of sills that intrude the Apache Group (central Arizona) and the Unkar Group (Grand Canyon) and supports earlier correlations of those units.

Rapid sea-level changes are generally interpreted in terms of glacio-eustasy, but they can also be explained by the lithospheric motions associated with changes in intra-plate stress. In eastern Spain, latest Senonian-Paleocene time was characterized by a widespread regression, which culminated in the emergence of large of parts of the carbonate platform. New data indicate that the platform emergence was accompanied by slope faulting and a sudden appearance of olistostromes and sandy turbidies at the southern Iberian margin of southeast Spain. These changes in basin geometry are the result of a tectonic event which is dated as middle Paleocene (ca. 60 Ma). This tectonic event can be correlated with the onset of collision in the Pyrenees. Regional geologic data and paleostress measurements provide evidence for far-field transmission of the Pyrenean compressive stresses through the Iberian lithosphere. It is concluded that the platform emergence and slope steepening at the southern Iberian margin reflect the vertical lithospheric motions of a basin flank subjected to compression.

Cogent interpretations of data bearing on the Cretaceous/Tertiary (K/T) extinction controversy depend on the existence of accurate chronostratigraphic models for the various K/T boundary sections. We have employed the graphic correlation technique to summarize biostratigraphic and lithostratigraphic data from 15 intensively sampled K/T boundary sections within a common chronostratigraphic model. Our results indicate that almost all of these sections, along with 13 additional boundary sections not used to construct the model, contain prolonged and in many cases multiple hiatuses. Of these 28 boundary sections, only six were found to contain a continuous record of sediment accumulation across the K/T boundary itself. These six K/T-complete sections are El Kef (Tunisia), Agost (Spain), Caravaca (Spain), and three sections along the Brazos River (Texas). A comparative analysis of hiatus distribution among these 28 K/T boundary sections also reveals the presence of systematic differences between continental-shelf and deep-sea depositional environments. The lower Danian interval immediately following the K/T boundary, and extending into biochronzones PO and Pla, is typically missing from the deep sea, whereas boundary sections deposited in shallower middle-neritic to upper-slope environments are in most case complete across the K/T boundary. These shallow, neritic boundary sections, however, are in many instance disrupted by hiatuses at the PO/P1a boundary and again in the upper part of Zone P1a. These differenial patterns of hiatus distribution between deepsea and continental-shelf depositional settings appear to be linked to sea-level fluctuations. Our data suggest that the apparently sudden mass extinction of planktonic Foraminifera and anomalities in the occurrence of geochemical tracers that are characteristic of the K/T boundary in deep-sea sections may be artifacts of a temporally incomplete deep-sea stratigraphic record.

The Pliocene-Pleistocene stages defined for the Mediterranean region are generally used as the standard chronostratigraphic units for the upper Neogene and Quaternary. The recently developed calcareous plankton biochronology based on results from Ocean Drilling Program Leg 107 and numerous outcrop sections provides the necessary time control for evaluating the ages and stratigraphic relationships for the various Pliocene-Pleistocene stages and their associated stratotypes. Our results indicate that the currently accepted stratotypes do not provide a continuous stratigraphic representation for all of Pliocene-early Pleistocene time. On the basis of these findings, we proposed a revised chronostratigraphic scheme for this time period. A tripartite subdivision is proposed for the Pliocene Series. The Zanclean Stage is retained for the lower Pliocene, representing the interval from the Miocene/Pliocene boundary (ca. 4.93 Ma) to ca. 3.5 Ma. The middle Pliocene is represented by the Piacenzian Stage, and it incorporates strata deposited from ca. 3.5 to 2.5 Ma. None of the currently used Pliocene stages fully represents the upper Pliocene (ca. 2.5 to 1.6 Ma.) As a result, late Pliocene time lacks an adequately defined chronostratigraphic unit. The Selinuntian Stage appears to be the most appropriate stage for the lower Pleistocene (ca. 1.6 to 0.8 Ma). It can be divided into three stratigraphically continuous substages (Santernian, Emilian, and Sicilian). The Calabrian Stage, which is commonly used to designate the lowest part of the Pleistocene, should be abandoned because its stratotype does not include a record of the first 500,000 yr of Pleistocene time.

The history of late Wisconsinan, pre-Valley Heads glaciation (about 18-15.5 ka) implies that major glaciological controls, as well as overall climatic warming, influenced the pattern of deglaciation in the western Mohawk Valley. The Middleville Formation in the West Canada Valley containst the most complete record of pre-Valley Heads ice recession in central New York. The lithostratigraphic succession was determined through detailed mapping and logging of measured sections, provenance study of diamicton units, and the analysis of declination of detrital remanent magnetization (DRM) in laminated lacustrine silt and clay. The initial recession of southwest-flowing ice from the Adirondacks and at least two glacial readvances of the Mohawk Lobe are recorded in these units. Glacial Lake Newport, impounded in the West Canada Valley during ice recession, attained levels that required ice-damming by coalescent Ontario and Mohawk Lobes and a subglacial outlet across the Mohawk Valley to the Susquehanna drainage basin. Initial ice recession in the Mohawk Valley was mostly by calving of active valley lobes in deep-water (up to 350 m) embayments and not by regional stagnation and simple downwasting. A shift of ice flow from the Adirondacks to ice flow from the Mohawk Lobe marks the development of low-land lobes during pre-Valley Heads time before the complete uncovering of the Adirondacks. The later dominance of the Ontario Lobe in Valley Heads time may have been the result of (1) a reduced supply of ice to the Mohawk Lobe from a diminished Adirondack ice dome, (2) changing ice-flow conditions in Quebec associated with an eastern St. Lawrence ice stream and calving bay, and (3) nonsynchronous surging of the Mohawk and Ontario Lobes as these lobes became fronted by deep lacustrine waters at different times.

Recognition of depositional sequences in Upper Cretaceous strata in the Kaiparowits Plateau allows examination of facies-tract geometries within coeval shoreface, alluvial, and coal-bearing strata. Changes in depositional architecture, sandstone-connectedness, sandshale ratios, coal-bed geometry, and degree of shoreface and foreshore preservation are related to position within a depositional sequence. Base-level falls produced regionally extensive sequence boundary unconformities and a basinward shift in facies tracts. Slow rates of base-level rise resulted in amalgamated fluvial channel complexes, thin discontinuous coal beds, and progradational shoreface parasequence sets. More rapid rates of base-level rise produced vertically isolated meander-belt sandstones, thick extensive coal beds, and aggradational shoreface parasequence sets. The highest rates of base-level rise resulted in retrogradational shoreface parasequences and tidally influenced fluvial systems at least 60 km inland of coeval shoreface deposits.

The worldwide occurrence of Au ores associated with Phanerozoic strata reveals a bimodal temporal association with either older Paleozoic or younger Mesozoic successions. These strata were deposited mostly in passive-margin environments synchronously with formation of volcanogenic massive-sulfide ores on active margins, during times of high sea level, widespread submarine oceanic volcanism, reduced and, at least locally, sulfidic oceans, and episodes of ocean anoxia. This correspondence of ocean properties and ages of strata that host Au seems beyond coincidence. Cause and effect cannot yet be described with confidence, but beyond the evolution of chemically reduced strata, the reduced oceans may also have been favorable to the enhancement of Au in certain strata that may constitute metallotects of Au.

Three entelodont teeth found in the bed of the Conecuh River in Alabama in 1968 are identified as belonging to Dinohyus aff. D. Hollandi and described. The discovery's significance as the first record of an Oligocene or early Miocene mammal in Alabama is discussed. Since the teeth were not found in situ, they must have been eroded from any of the area formations of the Oligocene or Miocene. Implications for correlations between strata of the continental interior and the Gulf Coastal plain are mentioned.

Magnetic susceptibility data from marine rocks can be used for global correlation because of synchronous variations in global erosion. We show here correlations between magnetic susceptibility data from two Lower Devonian, biostratigraphically well defined sections, one in northwestern Spain, and one from the Anti-Atlas region of Morocco. Using the Moroccan outcrop section, we correlate to cuttings from a Bolivian well with minimal biostratigraphic control. Using the magnetic susceptibility data, we identify the Lower Devonian, Pragian-Emsian, and lower-upper Emsian stage boundaries in the Bolivian well samples. Keywords: magnetic susceptibility, global correlation, Devonian, Emsian.

This paper deals with the problem of classification of nonstationary signals using signatures which are essentially independent of the signal length. This independence is a requirement in common classification problems like stratigraphic analysis, which was a motivation for this research. We achieve this objective by developing the notion of an approximation to the continuous wavelet transform, which is separable in the time and scale parameters, and using it to define power signatures, which essentially characterize the scale energy density, independent of time. We present a simple technique which uses the singular value decomposition to compute such an approximation, and demonstrate through an example how it is used to perform the classification. The proposed classification approach has potential applications in areas like moving target detection, object recognition, oil exploration, and speech processing.

At least 30 transgressive-regressive cycles of deposition are recognized from the upper Desmoinesian East Mountain Shale to the mid-Virgilian Wayland Shale in north-central Texas. Maximum regressive deposits are typically paleosol mudstones and fluvial sandstones; maximum transgressive deposits are typically widespread, ammonoid-bearing, conodont-rich, dark phosphatic shales in more major cycles, and persistent fossiliferous shales or limestones overlying terrestrial deposits in more minor cycles. Delta complexes dominate the regressive sequences of many cycles. Using biostratigraphic criteria of first, last, sole, or acme occurrence of ammonoid, conodont, and fusulinid taxa, we correlate 17 cycles in the Texas sequence directly with 17 glacial-eustatic cycles of similar magnitude in the northern midcontinent. This correlation sugests that glacial eustacy was the basic control over the cyclic sequence in Texas, that tectonic masking of the eustatic signal by nearby orogenic movement in Texas was negligible, and that delta shifting, though conspicuous, was only a secondary control over the cyclicity there. Minor cycles recognized between the correlated cycles also match well enough between Texas and the midcontinent to further discount potential tectonic or deltaic masking of glacial-eustatic cyclicity. This strengthens the likelihood of correlating glacial-eustatic events across larger parts of North America, and perhaps with other parts of the world.

The northern Death Valley-Furnace Creek fault zone is a major northwest-trending fault system in the Death Valley region, but the magnitude of offset and its significance to extensional tectonism in the region are controversial. Stratigraphic data have provided first-order constraints on offset across the fault zone but offer limited resolution. Previous correlations of Mesozoic thrust faults across the fault zone have relied on regional stratigraphic trends to fingerprint structurally similar thrust plates. We show that a northeast-trending Mesozoic backfold within the predominantly east-directed fold and thrust belt was probably continuous from the southern Panamint Range, California, to the Belted Range, Nevada. The relative position of this antithetic structure allows uniquely compatible correlations of three Mesozoic structures between two range blocks across the northern Death Valley-Furnace Creek fault zone independent of stratigraphic arguments. The offset structures have geometric properties of size, vergence, order, and spacing that indicate a probability less than [10.sup.-4] of the Mesozoic orogen identically repeating this structural suite in two unrelated places. Reconstruction of these correlative structures indicates 68 [+ or -] 4 km N48 [degrees]W [+ or -] 6 [degrees]W of apparent dextral offset between the Cottonwood and Funeral Mountains, in general agreement with previous estimates based on stratigraphic observations but of substantially higher precision. This reconstruction, and the restoration of a 30-km separation between the Funeral and Grapevine Mountains indicated by offset segments of the backfold, suggest a simple pre-extensional geometry for the Mesozoic orogen in the Death Valley region consistent with observations from unextended blocks and analogous to that of the Cordilleran orogen at the latitude of Calgary, Alberta.

Bootstrap methods for estimating spatial correlations used in population ecology is described and examined. Results reveal that resampling of locations performed badly, with true coverage level as low as 30-40%, especially for small correlations at long distances.

We report the first discovery of abundant Devonian vertebrates from Thailand. An unusual form of coronodontid shark tooth with six equal-sized cusps occurs only in the Upper Devonian of Thailand (Shan-Thai terrane) and south China, and a new species of Phoebodus is reported that occurs elsewhere only in south China and Australia (east Gondwana terrane). The occurrence of the chondrichthyan Harpagodens (Thrinacodus) ferox Turner 1982 in the Late Devonian of Thailand, Australia, and south China predates the appearance of this species in Euramerica (early Carboniferous). These data suggest Late Devonian proximity of the Shan-Thai, south China, and east Gondwana terranes, and is in accord with recent paleomagnetic data.

Time-Transgressive Late Cenozoic Radiolarian Events of the Equatorial Indo-Pacific A fundamental presumption of stratigraphic correlation is that biostratigraphic datum levels (first or last appearances of taxa) are synchronous, whereas other [...]

We present detailed isotope stratigraphies for Carboniferous time based on brachiopod shell calcite from the midcontinent region of North America. Evidence for shell calcite preservation includes (1) preservation of shell microstructure, (2) lack of cathodoluminescence, (3) low Si, Al, Fe, and Mn contents, (4) Na, Sr, and S contents comparable to those of modern brachiopod shells, and (5) [[Delta].sup.13]C and [[Delta].sup.18]O values higher than those of associated cements and matrix. The Carboniferous [[Delta].sup.13]C record for North America is characterized by three isotopic stages. The earliest stage, C1, follows a 2.0[per thousand] increase in Kinderhookian time (early Tournaisian), from 1.5[per thousand] to 3.5[per thousand], and includes a brief and perhaps local late Kinderhookian excursion to 5.4[per thousand]. The [[Delta].sup.13]C values remain stable at 3.5[per thousand] to 4[per thousand] during stage C1, then decrease about 1[per thousand] near the Meramecian-Chesterian boundary (Visean) to 2[per thousand]-3[per thousand] (stage C2). Stage C2 ends with a 1[per thousand]-2[per thousand] increase (C2-C3 transition) between middle Chesterian and early Morrowan time (Serpukhovian-Bashkirian). Stage C3 values remain mostly between 3[per thousand] and 4.5[per thousand] upsection to Virgilian strata (Gzhelian). Increases in [[Delta].sup.13]C probably reflect global increases in sedimentary organic carbon burial and suggest that p[CO.sub.2] declines in the earliest and middle Carboniferous strata. The middle Carboniferous [[Delta].sup.13]C shift of B. Popp, T. Anderson, and P. Sandberg, an [approximately]3[per thousand] increase in European sections, occurs in North America (C2-C3 transition) but is limited to [approximately]1.5[per thousand]. This 1.5[per thousand] increase was probably caused by increased organic carbon burial, whereas the additional [approximately]1.5[per thousand] shift in European sections likely reflects changes in ocean circulation patterns associated with the closing of the Equatorial seaway. based on the timing of the [[Delta].sup.13]C divergence between North America and Europe, the isolation of the Paleotethys began in late Chesterian time (Serpukhovian). The [[Delta].sup.18]O record can also be separated into the three stages. There is a 3[per thousand] increase during Kinderhookian-Osagean time (Tournaisian), corresponding to the Devonian to Carboniferous transition to stage C1, a 3[per thousand] decrease during Meramecian-early Chesterian time (Visean; C1-C2 transition), then a 2[per thousand] increase in late Chesterian-early Morrowan time (Serpukhovian-Bashkirian; C2-C3 transition). The [[Delta].sup.18]O values then fluctuate between -1[per thousand] and -3[per thousand] (C3 stage) upsection to the Virgilian strata (Gzhelian). If global, the 2[per thousand] to 3[per thousand] [[Delta].sup.18]O shifts are compelling evidence for cooling and glaciation in Early Mississippian time, warming and deglaciation in Late Mississippian time, and a return to cool, glacial conditions in earliest Pennsylvanian time. The general correlation between [[Delta].sup.13]C and [[Delta].sup.18]O shifts suggests that cooling is associated with drawdown of atmospheric C[O.sub.2].