43 results
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2. Middle Cenomanian (Late Cretaceous) molluscs of the Shaftesbury Formation, Birch Mountains, northeastern Alberta, Canada.
- Author
-
Bohach, Lisa L. and Frampton, Emily K.
- Subjects
GEOGRAPHICAL distribution of fossil mollusks ,GEOGRAPHICAL distribution of mollusks ,CRETACEOUS Period ,CLIFFS ,MOUNTAINS - Abstract
Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2015
- Full Text
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3. The Jackass Mountain Group of south-central British Columbia: depositional setting and evolution of an Early Cretaceous deltaic complex.
- Author
-
MacLaurin, Catherine I., Mahoney, J. Brian, Haggart, James W., Goodin, J. Russell, Mustard, Peter S., and Doe, John
- Subjects
SEDIMENTATION & deposition ,MOUNTAINS ,MARINE sediments ,STRUCTURAL geology ,CRETACEOUS stratigraphic geology ,SEDIMENTOLOGY ,PETROLOGY - Abstract
Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2011
- Full Text
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4. Tectonic implications of 40Ar/39Ar muscovite dates from the Mt. Haley stock and Lussier River stock, near Fort Steele, British Columbia.
- Author
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Larson, Kyle P., Price, Raymond A., and Archibald, Douglas A.
- Subjects
STRUCTURAL geology ,ARGON ,MUSCOVITE ,RIVERS ,MOUNTAINS ,GEOLOGIC faults ,IGNEOUS intrusions ,PHYSICAL geology - Abstract
Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2006
- Full Text
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5. Depositional and tectonic setting of the Miocene Wood Mountain Formation, southern Saskatchewan.
- Author
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Leckie, Dale A, Bednarski, Jan M, and Young, Harvey R
- Subjects
WOOD ,MORPHOTECTONICS ,STRUCTURAL geology ,MOUNTAINS ,LANDFORMS ,EROSION - Abstract
Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2004
- Full Text
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6. Research on the fracture structure and activity of the Qinling Mountains thrust nappe system in western Hubei.
- Author
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Lin, Song, Li, Yuan, Luo, Denggui, and Fu, Yanlin
- Subjects
THERMOLUMINESCENCE dating ,GEOLOGICAL surveys ,QUATERNARY Period ,GEOPHYSICAL prospecting ,MOUNTAINS ,SCANNING electron microscopy - Abstract
Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2020
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7. Fishes from the Lower Triassic portion of the Sulphur Mountain Formation in Alberta, Canada: geological context and taxonomic composition.
- Author
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Neuman, Andrew G.
- Subjects
FOSSIL fishes ,GEOGRAPHICAL distribution of fishes ,COLLECTION & preservation of fish ,TRIASSIC Period ,MOUNTAINS - Abstract
Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2015
- Full Text
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8. Crustal magnetic anomaly and Curie surface beneath Tarim Basin, China, and its adjacent area.
- Author
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Gao, Guoming, Kang, Guofa, Li, Guangquan, Bai, Chunhua, and Enkin, Randolph
- Subjects
GEOMAGNETISM ,MAGNETIC anomalies ,GEOLOGICAL basins ,MOUNTAINS - Abstract
Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2015
- Full Text
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9. A low-relief hill in eastern Ontario, Canada, covered by the easily erodible Queenston Formation and derived sediments - probably the result of Quaternary tectonic uplift.
- Author
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Wallach, J.L. and Mahoney, Brian
- Subjects
MOUNTAINS ,SEDIMENTS ,STRUCTURAL geology ,GEODYNAMICS - Abstract
Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2014
- Full Text
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10. Bokan Mountain peralkaline granitic complex, Alexander terrane (southeastern Alaska): evidence for Early Jurassic rifting prior to accretion with North America.
- Author
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Dostal, Jaroslav, Karl, Susan M., Keppie, J. Duncan, Kontak, Daniel J., Shellnutt, J. Gregory, and Murphy, Brendan
- Subjects
GEOLOGIC faults ,JURASSIC stratigraphic geology ,ACCRETION (Astrophysics) ,IGNEOUS intrusions ,GEODYNAMICS ,MINERALIZATION ,MOUNTAINS - Abstract
Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2013
- Full Text
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11. Late Holocene glacial activity at Bromley Glacier, Cambria Icefield, northern British Columbia Coast Mountains, Canada.
- Author
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Hoffman, Kira M., Smith, Dan J., and Fisher, Timothy
- Subjects
HOLOCENE stratigraphic geology ,GLACIOLOGY ,DENDROCHRONOLOGY ,RADIOCARBON dating ,SEDIMENTATION & deposition ,GEOLOGICAL formations ,MOUNTAINS - Abstract
Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2013
- Full Text
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12. U-Pb geochronology in Liverpool Land and Canning Land, East Greenland - the complex record of a polyphase Caledonian orogeny.
- Author
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Corfu, Fernando and Hartz, Ebbe H.
- Subjects
URANIUM-lead dating ,GEOLOGICAL time scales ,MULTIPHASE flow ,OROGENY ,MOUNTAINS - Abstract
The Liverpool Land - Canning Land region in East Greenland is the central-most basement high in the northeast Atlantic Caledonides. It contains a variety of rocks derived from the whole section of the Caledonian crust, permitting correlations and comparisons of tectonomagmatic events at all crustal levels. Here, we present U-Pb thermal ionization mass spectrometry (TIMS) data combined with field studies suggesting that the region can be divided into distinct tectonostratigraphic domains: (1) The Southern Liverpool Land eclogite terrane with garnet-peridotite and eclogite lenses, the product of a polyorogenic history with a latest-Paleoproterozic and Mesoproterozoic origin, eclogitization at 398 Ma and migmatization at 387 Ma. (2) The migmatitic Mariager Fjord Dome in central Liverpool Land with gneisses that formed leucosome at 409 Ma. Both areas are separated by high-strain zones from (3) the overlying Hurry Inlet plutonic terrane, which consists of metasedimentary rocks first intruded by granodiorite to granite at ca. 440-430 Ma, and, after local deformation, by a major 426-424 Ma granitic to monzonitic suite. (4) Structurally higher, and probably above another high-strain zone, low-grade Neoproterozoic to Cambrian sediments are intruded, by syn-contractional 427 Ma leucogranite. All these units are unconformably overlain by Devonian and younger deposits. Collectively our data document a distinct variation in time for Caledonian magmatism and metamorphism in the various tectonostratigraphic domains, implying that the diverse terranes were juxtaposed after magmatism, and that the gneiss domes of Liverpool Land have a different origin than other nappes of the East Greenland Caledonides. La région de Liverpool Land - Canning Land dans l'Est du Groenland est le point central le plus élevé du socle dans les Calédonides de l'Atlantique du Nord-Est. Elle contient une variété de roches provenant de toute la section de la croûte calédonienne, permettant d'établir des corrélations et des comparaisons d'événements tectonomagmatiques à tous les niveaux de la croûte. Nous présentons ici des données U-Pb TIMS combinées à des études sur le terrain suggérant que la région puisse être divisée en des domaines tectonostratigraphiques distincts : (1) le terrane éclogite de Southern Liverpool Land avec des lentilles de péridotite à grenat et d'éclogite, soit le produit d'un historique polyorogénique dont l'origine date du Paléoprotérozoïque sommital et du Mésoprotérozoïque, avec éclogitisation à 398 Ma et migmatisation à 387 Ma; (2) le dôme migmatitique du fjord Mariager dans le centre du Liverpool Land avec des gneiss qui ont formé des leucosomes à 409 Ma. Les deux régions sont séparées par des zones de contraintes élevées du terrane plutonique sus-jacent Hurry Inlet (3), lequel comprend des roches métasédimentaires qui ont été pénétrées par une suite granodioritique à granitique vers 440-430 Ma et, après une déformation locale, par une suite monzonitique à granitique importante (426-424 Ma); (4) à un niveau structural supérieur et probablement au-dessus d'une autre zone de contraintes élevées, des sédiments faiblement métamorphisés (Néoprotérozoïque à Cambrien) sont pénétrés par un leucogranite de contraction synchrone à 427 Ma. Des dépôts dévoniens et plus récents recouvrent toutes ces unités de manière discordante. Prises ensemble, nos données documentent une variation distincte dans le temps pour le magmatisme et le métamorphisme calédoniens dans divers domaines tectonostratigraphiques, signifiant que les divers terranes ont été juxtaposés après le magmatisme et que les dômes de gneiss du Liverpool Land ont une origine différente des autres nappes des Calédonides de l'Est du Groenland. [ABSTRACT FROM AUTHOR]
- Published
- 2011
13. Revision of the status of Saurolophus (Hadrosauridae) from California, USA.
- Author
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Bell, Phil R. and Evans, David C.
- Subjects
SKULL ,HADROSAURIDAE ,MOUNTAINS ,ORNITHISCHIA ,PHYLOGENY - Abstract
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- Published
- 2010
14. Ediacaran body and trace fossils in Miette Group (Windermere Supergroup) near Salient Mountain, British Columbia, Canada.
- Author
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Hofmann, Hans J. and Mountjoy, Eric W.
- Subjects
TRACE fossils ,MOUNTAINS ,GEOLOGICAL time scales ,NEMATOMORPHA ,CARBONATES ,LAURENTIA (Continent) - Abstract
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- Published
- 2010
15. The Lower Triassic Sulphur Mountain Formation in the Wapiti Lake area: lithostratigraphy, conodont biostratigraphy, and a new biozonation for the lower Olenekian (Smithian).
- Author
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Orchard, M. J. and Zonneveld, J.-P.
- Subjects
TRIASSIC stratigraphic geology ,CONODONTS ,GEOLOGICAL formations ,MOUNTAINS ,BIOSTRATIGRAPHY - Abstract
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- Published
- 2009
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16. Basin architecture and syndepositional fault activity during deposition of the Neoproterozoic Mackenzie Mountains supergroup, Northwest Territories, Canada.
- Author
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Turner, Elizabeth C. and Long, Darrel G.F.
- Subjects
INSTRUMENT landing systems ,ERHARD seminars training ,FLUID mechanics ,LITHOFACIES ,LANDFORMS ,GEOLOGICAL formations ,MOUNTAINS ,STRATIGRAPHIC geology - Abstract
The early Neoproterozoic Mackenzie Mountains supergroup (MMSG; ~4 km thick, <1083 Ma, >779 Ma) was deposited in a large but poorly understood basin. Analysis of new and existing stratigraphic data reveals unexpected, abrupt changes in thickness and lithofacies patterns in formation scale and smaller units over short distances parallel and perpendicular to depositional strike. These isopach and lithofacies patterns depict irregularly subsiding syndepositional sub-basins. These basins may have developed during basin extension in a lower-plate segment of an evolving passive margin, as the result of episodic, excessive subsidence along growth faults parallel to the basin margin, and crustal-scale (transfer) faults at a high angle to the margin. The extent of the lower-plate area is inferred to correspond to the distribution of the MMSG (~500 km strike length); upper-plate segments are inferred to flank the MMSG embayment to the northwest and southeast. A lower-plate model for the arcuate MMSG embayment has important implications for the Mackenzie Mountains zinc district. The present-day regional distribution of known carbonate-hosted base-metal showings suggests that the configuration of the thinned, faulted Neoproterozoic lower-plate segment, together with later reactivation of basement-rooted transfer faults during Neoproterozoic–Paleozoic rifting or Laramide compression, may have been important in focussing metalliferous fluids into overlying units. Le Supergroupe de Mackenzie Mountains, datant du Néoprotérozoïque (épaisseur ~4 km, <1083 Ma, >779 Ma) a été déposé dans un bassin vaste mais mal défini. L’analyse de données stratigraphiques, nouvelles et existantes, révèle des changements inattendus et brusques dans l’épaisseur et les patrons des lithofaciès à l’échelle de la formation et de plus petites unités sur de courtes distances parallèles et perpendiculaires à la direction de la déposition. Ces patrons d’isopaches et de lithofaciès décrivent des sous-bassins synsédimentaires à subsidence irrégulière. Ces bassins se sont possiblement développés durant une extension d’un bassin dans un segment de plaque inférieure d’une bordure passive en évolution et ils auraient été causés par une subsidence épisodique et excessive le long de failles de croissance parallèles à la bordure du bassin et le long de failles (de transfert) à l’échelle de la croûte à un angle élevé par rapport à la bordure. L’étendue du secteur de la plaque inférieure correspondrait à la distribution du Supergroupe de Mackenzie Mountains (sur une longueur ~500 km selon la direction) et les segments de la plaque supérieure longeraient l’enfoncement du Supergroupe de Mackenzie Mountains au nord-ouest et au sud-est. Un modèle de plaque inférieure pour l’enfoncement arqué du Supergroupe de Mackenzie Mountains a des implications importantes pour le district du zinc des monts Mackenzie. La distribution actuelle régionale connue d’indices de métaux de base dans des carbonates suggère que la configuration du segment inférieur néoprotérozoïque, aminci et faillé, et une réactivation postérieure des failles de transfert dans le socle au cours du Néoprotérozoïque – distension au Paléozoïque ou compression durant la compression laramienne, puissent avoir joué un rôle significatif dans la concentration des fluides métallifères dans les unités sus-jacentes. [ABSTRACT FROM AUTHOR]
- Published
- 2008
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17. Assessing the role of orogen-parallel faulting in post-orogenic exhumation: low-temperature thermochronology across the Norumbega Fault System, Maine.
- Author
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West, David P., Roden-Tice, Mary K., Potter, Jaime K., and Barnard, Nellie Q.
- Subjects
NORUMBEGA Fault Zone (Me.) ,OROGENIC belts ,APATITE ,MOUNTAINS ,SILURIAN stratigraphic geology - Abstract
Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2008
18. Dendroglaciological evidence for Holocene glacial advances in the Todd Icefield area, northern British Columbia Coast Mountains.
- Author
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Jackson, Scott I., Laxton, Sarah C., and Smith, Dan J.
- Subjects
ICE ,GLACIERS ,GLACIAL crevasses ,DENDROCHRONOLOGY ,CARBON isotopes ,ABIES lasiocarpa ,MOUNTAINS ,PLEISTOCENE stratigraphic geology - Abstract
Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2008
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19. Late Holocene glacial activity of Bridge Glacier, British Columbia Coast Mountains.
- Author
-
Allen, Sandra M. and Smith, Dan J.
- Subjects
HOLOCENE stratigraphic geology ,QUATERNARY stratigraphic geology ,MOUNTAINS ,GLACIERS - Abstract
Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2007
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20. Ediacaran U–Pb zircon dates for the Lac Matapédia and Mt. St.-Anselme basalts of the Quebec Appalachians: support for a long-lived mantle plume during the rifting phase of Iapetus opening.
- Author
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Hodych, Joseph P. and Cox, Richard A.
- Subjects
MAGMATISM ,FLOOD basalts ,LAVA flows ,VOLCANISM ,MASS spectrometers ,SPECTRUM analysis instruments ,GEOCHEMISTRY ,MOUNTAINS - Abstract
Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2007
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21. The sequence and correlation of Early Ordovician (Arenig) graptolite faunas in the Richardson Trough and Misty Creek Embayment, Yukon Territory and District of Mackenzie, Canada.
- Author
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Jackson, D. E. and Lenz, A. C.
- Subjects
ANIMALS ,GRAPTOLITES ,FOSSIL chordata ,ORDOVICIAN stratigraphic geology ,CHERT ,CRYSTALLINE rocks ,MOUNTAINS - Abstract
Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2006
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22. The Teton – Wind River domain: a 2.68–2.67 Ga active margin in the western Wyoming Province.
- Author
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Frost, B. Ronald, Frost, Carol D., Cornia, Mary, Chamberlain, Kevin R., and Kirkwood, Robert
- Subjects
METAMORPHIC rocks ,GEODYNAMICS ,PLATE tectonics ,BATHOLITHS ,GNEISS ,AMPHIBOLITES ,MOUNTAINS - Abstract
Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2006
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23. 2480 Ma mafic magmatism in the northern Black Hills, South Dakota: a new link connecting the Wyoming and Superior cratons.
- Author
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Dahl, Peter S., Hamilton, Michael A., Wooden, Joseph L., Foland, Kenneth A., Frei, Robert, McCombs, James A., and Holm, Daniel K.
- Subjects
PRECAMBRIAN stratigraphic geology ,MAGMATISM ,SEDIMENTATION & deposition ,SPHENE ,ZIRCON ,CRATONS ,MOUNTAINS - Abstract
Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2006
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24. Tectonic histories of the Paleo- to Mesoarchean Sacawee block and Neoarchean Oregon Trail structural belt of the south-central Wyoming Province.
- Author
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Grace, Rashmi L. B., Chamberlain, Kevin R., Frost, B. Ronald, and Frost, Carol D.
- Subjects
ARCHAEAN stratigraphic geology ,GNEISS ,METAMORPHIC rocks ,ZIRCON ,AMPHIBOLITES ,OREGON Trail ,MOUNTAINS - Abstract
Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2006
- Full Text
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25. Archean geochronological framework of the Bighorn Mountains, Wyoming.
- Author
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Frost, Carol D. and Fanning, C. Mark
- Subjects
ARCHAEAN stratigraphic geology ,GEOLOGICAL time scales ,PLATE tectonics ,IGNEOUS intrusions ,ZIRCON ,SPHENE ,GRANITE ,GNEISS ,MOUNTAINS - Abstract
Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2006
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26. Precambrian history of the eastern Ferris Mountains and Bear Mountain, south-central Wyoming Province.
- Author
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Chamberlain, Kevin R. and Bowers, Nancy E.
- Subjects
ARCHAEAN stratigraphic geology ,PRECAMBRIAN paleoclimatology ,PRECAMBRIAN paleomagnetism ,IGNEOUS intrusions ,METAMORPHISM (Geology) ,MAGMATISM ,MOUNTAINS - Abstract
Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2006
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27. Archean crustal growth by lateral accretion of juvenile supracrustal belts in the south-central Wyoming Province.
- Author
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Frost, Carol D., Fruchey, Benjamin L., Chamberlain, Kevin R., and Frost, B. Ronald
- Subjects
ARCHAEAN stratigraphic geology ,VOLCANIC ash, tuff, etc. ,MOUNTAINS ,MAGMATISM ,IGNEOUS intrusions ,PLATE tectonics - Abstract
Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2006
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28. Structural variation along the Devil's Mountain fault zone, northwestern Washington.
- Author
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Hayward, Nathan, Nedimovi&##x0107;, Mladen R., Cleary, Matthew, and Calvert, Andrew J.
- Subjects
SURVEYS ,TOMOGRAPHY ,SEISMIC reflection method ,MOUNTAINS ,SEISMIC prospecting ,UPLANDS - Abstract
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- Published
- 2006
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29. Early Paleozoic development of the Maine-Quebec Boundary Mountains region.
- Author
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Gerbi, C. C., Johnson, S. E., Aleinikoff, J. N., Bédard, J. H., Dunning, G. R., and Fanning, C. M.
- Subjects
CRATONS ,IGNEOUS rocks ,OPHIOLITES ,GABBRO ,TONALITE ,GRANODIORITE ,IGNEOUS intrusions ,MOUNTAINS - Abstract
Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2006
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30. Snow avalanche activity after fire and logging disturbances, northern Gaspé Peninsula, Quebec, Canada.
- Author
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Germain, Daniel, Filion, Louise, and Hétu, Bernard
- Subjects
AVALANCHES ,SNOW ,ECOLOGICAL disturbances ,FOREST fires ,LOGGING ,TREE-rings ,SLOPES (Physical geography) ,TREES ,MOUNTAINS - Abstract
Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
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- 2005
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31. Helmolepis cyphognathus, sp. nov., a new platysiagid actinopterygian from the Lower Triassic Sulphur Mountain Formation (British Columbia, Canada).
- Author
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Neuman, Andrew G. and Mutter, Raoul J.
- Subjects
SULFUR ,MOUNTAINS ,NATIVE element minerals ,GEOLOGY ,EARTH sciences - Abstract
Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2005
- Full Text
- View/download PDF
32. Felsenmeer persistence under non-erosive ice in the Torngat and Kaumajet mountains, Quebec and Labrador, as determined by soil weathering and cosmogenic nuclide exposure dating.
- Author
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Marquette, Geneviève C., Gray, James T., Gosse, John C., Courchesne, François, Stockli, Lisa, Macpherson, Gwen, and Finkel, Robert
- Subjects
WEATHERING ,NUCLIDES ,SOIL testing ,MOUNTAINS ,ICE sheets - Abstract
Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2004
- Full Text
- View/download PDF
33. Tectonic implications of magnetic fabrics and remanence in the Cooper Mountain pluton, North Cascade Mountains, Washington.
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Fawcett, Tammy C, Burmester, Russell F, Housen, Bernard A, and Iriondo, Alexander
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STRUCTURAL geology ,IGNEOUS intrusions ,MAGNETITE ,MOUNTAINS ,PALEOMAGNETISM - Abstract
Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2003
- Full Text
- View/download PDF
34. The distribution of igneous rocks beneath Mont Mégantic (the easternmost Monteregian) as revealed by gravity.
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Feininger, Tomas and Goodacre, Alan K.
- Subjects
GRAVITY ,IGNEOUS rocks ,MOUNTAINS ,GEOLOGY ,GEOPHYSICS - Abstract
Focuses on a study which analyzed the effect of gravity on the distribution of igneous rocks beneath Mont Mégantic hill. Significance of the present study; Geology; Rock density; Gravity; Discussion.
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- 2003
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35. Physical and chemical properties of the Sulphur Mountain thermal springs, Banff National Park, and implications for endangered snails.
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Grasby, Stephen E and Lepitzki, Dwayne A.W
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HOT springs ,GEOTHERMAL resources ,MOUNTAINS ,CHEMICALS ,SULFUR - Abstract
Nine thermal springs, in three groups, occur along the flank of Sulphur Mountain in Banff National Park. The principal recharge zone is suggested to be above 2000 m elevation on Mount Rundle, circulation depths are estimated to be 3.2 ± 0.6 km, and discharge is focused along the Sulphur Mountain Thrust. Springs show constant temperature and total dissolved solids load throughout the winter, whereas both drop in association with spring snowmelt. The degree and timing of temperature drops are a function of elevation, with the highest springs showing the earliest and most significant temperature drop. The highest elevation springs also show the greatest seasonal variability in water chemistry. Unusual seasonal flow stoppages of these springs are related to extreme low precipitation years. The biogeochemistry of the thermal springs and population fluctuations of the endemic and endangered Banff springs snail (Physella johnsoni) are strongly related to seasonal variability in flow rates. Changes in redox conditions associated with an influx of shallow groundwater during spring snowmelt negatively impact the microbial community that forms a principal food supply for the snail.On retrouve neuf sources thermales, en trois groupes, le long du flanc du mont Sulphur dans le parc national Banff. La principale zone de recharge serait à plus de 2000 m sur le mont Rundle; on estime les profondeurs de circulation à 3,2 ± 0,6 km et la décharge se fait surtout le long du chevauchement du mont Sulphur. Tout au long de l'hiver, les sources ont des températures et des charges en matières dissoutes totales constantes; ces deux points chutent lors de la fonte printanière. Le degré et le moment des chutes de température sont une fonction de l'élévation, les sources les plus élevées montrant les chutes de température les plus précoces et les plus significatives. Les sources les plus élevées ont aussi la plus grande variabilité saisonnière de chimie de l'eau. Des arrêts d'écoulement saisonniers inhabituels de ces sources sont reliés à des années de précipitations extrêmement faibles. La biogéochimie des sources thermales et les fluctuations de la population de l'escargot des sources thermales de Banff (Physella johnsoni), endémique et menacé, sont fortement associées à la variabilité saisonnière des taux d'écoulement. Des changements dans les conditions redox associés à une arrivée d'eau souterraine peu profonde au cours de la fonte printanière ont des impacts négatifs sur la communauté microbienne qui forme la principale source d'alimentation de l'escargot.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]
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- 2002
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36. Flank collapse at Mount Wrangell, Alaska, recorded by volcanic mass-flow deposits in the Copper River lowland.
- Author
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Waythomas, Christopher F and Wallace, Kristi L
- Subjects
RIVERS ,MOUNTAINS ,LANDFORMS ,COPPER - Abstract
An areally extensive volcanic mass-flow deposit of Pleistocene age, known as the Chetaslina volcanic mass-flow deposit, is a prominent and visually striking deposit in the southeastern Copper River lowland of south-central Alaska. The mass-flow deposit consists of a diverse mixture of colorful, variably altered volcanic rocks, lahar deposits, glaciolacustrine diamicton, and till that record a major flank collapse on the southwest flank of Mount Wrangell. The deposit is well exposed near its presumed source, and thick, continuous, stratigraphic exposures have permitted us to study its sedimentary characteristics as a means of better understanding the origin, significance, and evolution of the deposit. Deposits of the Chetaslina volcanic mass flow in the Chetaslina River drainage are primary debris-avalanche deposits and consist of two principal facies types, a near-source block facies and a distal mixed facies. The block facies is composed entirely of block-supported, shattered and fractured blocks with individual blocks up to 40 m in diameter. The mixed facies consists of block-sized particles in a matrix of poorly sorted rock rubble, sand, and silt generated by the comminution of larger blocks. Deposits of the Chetaslina volcanic mass flow exposed along the Copper, Tonsina, and Chitina rivers are debris-flow deposits that evolved from the debris-avalanche component of the flow and from erosion and entrainment of local glacial and glaciolacustrine diamicton in the Copper River lowland. The debris-flow deposits were probably generated through mixing of the distal debris avalanche with the ancestral Copper River, or through breaching of a debris-avalanche dam across the ancestral river. The distribution of facies types and major-element chemistry of clasts in the deposit indicate that its source was an ancestral volcanic edifice, informally known as the Chetaslina vent, on the southwest side of Mount Wrangell. A major sector collapse of the Chetaslina vent initiated the Chetaslina volcanic mass flow forming a debris avalanche of about 4 km[sup 3] that subsequently transformed to a debris flow of unknown volume.Un dépôt de mouvement de masse de roches volcaniques, datant du Pléistocène, couvre une grande superficie; ce dépôt, connu sous le nom de dépôt de mouvement de masse de roches volcaniques de Chetaslina, est proéminent et visiblement frappant dans les basses-terres du sud-est de la rivière Copper, du centre-sud de l'Alaska. Le dépôt de mouvement de masse comprend un mélange varié, haut en couleur, de roches volcaniques à altération variable, de dépôts de lahar, de diamicton glacio-lacustre et de till qui rappellent un important effondrement de flanc sur le flanc sud-ouest du mont Wrangell. Le dépôt est bien exposé à proximité de sa source réputée et des affleurements stratigraphiques, continus et épais, nous ont permis d'étudier ses caractéristiques sédimentaires afin de mieux comprendre l'origine, la signification et l'évolution du dépôt. Les dépôts de mouvement de masse de roches volcaniques de Chetaslina, dans le bassin de drainage de la rivière Chetaslina, sont surtout des dépôts primaires d'avalanches de débris et comprennent deux principaux types de faciès, un faciès de blocs, à proximité de la source, et un faciès distal mixte. Le faciès de blocs est composé entièrement de blocs fracturés et éclatés soutenus par d'autres blocs; certains blocs atteignant 40 m de diamètre. Le faciès mixte comprend des particules de la dimension de blocs dans une matrice mal triée de débris rocheux, de sable et de silt provenant de la comminution de blocs plus gros. Les dépôts de mouvement de masse de roches volcaniques affleurant le long des rivières Copper, Tonsina et Chitina sont des dépôts de mouvement de masse de débris qui ont évolué à partir de la composante d'avalanche de débris du mouvement de masse et à partir également de l'érosion et de l'entraînement de diamictons glaciaux et glacio-lacustres locaux dans les basses-terres de la rivière Copper. Les dépôts de mouvement débris proviennent probablement du mélange d'une avalanche de débris distale et de la rivière ancestrale Copper ou par la rupture d'un barrage formé par une avalanche de débris en travers de la rivière ancestrale. La distribution des types de faciès et la chimie des éléments majeurs des clastes dans le dépôt indiquent que la source était un ancien édifice volcanique connu de façon informelle sous le nom de cheminée de Chetaslina, sur le côté sud-ouest du mont Wrangell. Un effondrement majeur du secteur de la cheminée de Chetaslina a provoqué le mouvement de masse des roches volcaniques de Chetaslina, formant une avalanche de débris d'environ 4 km[sup 3] qui s'est par la suite transformée en un écoulement de débris d'un volume inconnu.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]
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- 2002
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37. U–Pb geochronologic constraints on the crustal evolution of the Long Range Inlier, Newfoundland.
- Author
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Heaman, L M, Erdmer, Philippe, and Owen, J V
- Subjects
MOUNTAINS ,MAGMATISM ,LAKES - Abstract
The Long Range Mountains of Newfoundland expose the northeastern most basement inlier of the Appalachian Orogen. U–Pb results for two samples of basement gneiss reveal crustal formation ages of 1466 ± 10 Ma (Western Brook Pond charnockite) and 1530 ± 8 Ma (Cat Arm Road gneiss), indicating an affinity with Pinwarian magmatism (1510–1450 Ma) in Labrador. A third sample of basement gneiss from the Cat Arm Road dam site yielded a minimum formation age of 1631 Ma. These basement gneisses were intruded by granite plutons during two periods of Grenvillian magmatism; Group I at 1032–1022 Ma and Group II at 993–985 Ma. Group I intrusions include the 1032.0 ± 1.5 Ma Lomond River granite and the 1022.0 ± 2.0 Ma Lake Michel igneous suite; Group II intrusions include the 999 ± 4 Ma Potato Hill charnockite, 993 ± 7 Ma Horse Chops granite, 984.9 ± 1.6 Ma Cloud River granite, and may include the Apsy granite. The metamorphic history of the Long Range Inlier is complex and three discrete Proterozoic metamorphic events can be delineated on the basis of field relationships and U–Pb dates for metamorphic minerals. M[sub 1] metamorphism is a regional high-grade event that occurred prior to 1032 Ma, the emplacement age for the unmetamorphosed Lomond River granite. M[sub 2] and M[sub 3] occurred at 1022 and 989 Ma, respectively; coinciding with the two main periods of Grenvillian magmatism. The Precambrian crustal evolution of the Long Range Inlier is very similar to the Pinware terrane of Labrador, consistent with a single contiguous terrane presently separated by the Gulf of St. Lawrence. A surprising discovery from this study is identification of the first known occurrence of Silurian mafic magmatism in the Long Range Inlier, the 430.5 ± 2.5 Ma Taylor Brook gabbro.L'enclave du socle le plus au nord-est de l'orogène des Appalaches affleure dans les montagnes du Long Range à Terre-Neuve. Des résultats U–Pb de deux échantillons de gneiss du socle révèlent des âges de formation crustale de 1466 ± 10 Ma (la charnokite de Western Brook Pond) et de 1530 ± 8 Ma (le gneiss de Cat Arm Road) indiquant une affinité avec le magnétisme pinwarien (1510–1450 Ma) au Labrador. Un troisième échantillon de gneiss du socle, au site du barrage de Cat Arm Road, a donné un âge minimum de 1631 Ma pour sa formation. Ces gneiss du socle ont été pénétrés par des plutons granitiques au cours de deux périodes de magmatisme grenvillien; le Groupe I à 1032–1022 Ma et le Groupe II à 993–985 Ma. Les intrusions du Groupe I comprennent le granite de Lomond River, 1032,0 ± 1,5 Ma et la suite ignée de Lake Michel 1022,0 ± 2,0; les intrusions du Groupe II comprennent la charnokite de Potato Hill, 999 ± 4 Ma, le granite de Horse Chops, 993 ± 7 Ma, le granite de Cloud River, 984,9 ± 1,6 Ma, et peut aussi comprendre le granite d'Apsy. L'histoire métamorphique de l'enclave de Long Range est complexe et il est possible de délimiter trois événements métamorphiques distincts au Protérozoïque selon les relations de terrain et les datations U–Pb des minéraux métamorphiques. Le métamorphisme M[sub 1] représente un événement régional de niveau élevé qui a eu lieu avant 1032 Ma, soit l'âge de la mise en place du granite non métamorphosé de Lomond River. M[sub 2] et M[sub 3] ont eu lieu respectivement à 1022 et 989 Ma, coïncidant avec les deux périodes principales de magmatisme grenvillien. L'évolution crustale au Précambrien de l'enclave de Long Range est très similaire à celle du terrane de Pinware au Labrador, concordant avec un terrane contigu unique présentement séparé par le golfe du Saint-Laurent. Une découverte surprenante de cette étude est l'identification de la première occurrence connue de magmatisme mafique silurien dans l'enclave de Long Range, soit le gabbro de Taylor Brook, à 430,5 ± 2,5 Ma.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]
- Published
- 2002
- Full Text
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38. Step-pool and cascade morphology, Mosquito Creek, British Columbia: a test of four analytical techniques.
- Author
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Wooldridge, C L and Hickin, E J
- Subjects
RIVERS ,MOUNTAINS - Abstract
The identification and geometric definition of individual cascade and step-pool bedforms are investigated in a steep, coarse-grained, mountain stream, Mosquito Creek, by testing four analytical techniques: visual identification, zero-crossing, bedform differencing, and power spectral analysis. The test is the first use of these techniques in a headwater stream, and the analysis of two bed profiles showed that visual identification was able to (i) identify, (ii) determine the geometry of, and (iii) classify the type of individual bedforms better than the other methods. The other techniques were not able to differentiate step-pools from cascades, and the large range of grain sizes and bedform heights hampered their ability to consistently identify stepped bedforms. The step-pool (pronounced, channel-spanning steps that alternate with channel-spanning pools) and cascade (multi-tiered, partially channel-spanning structures) morphology in Mosquito Creek has formed in the last 20 years as fluvial action has restructured its previously engineered, revetment-lined, planar bed. The channel bed exhibits a morphologic regularity that power spectral analysis captured as periodic fluctuations in the bed profiles, with mean wavelengths slightly greater than those identified by the other methods. Further, the active reorganization of revetment has formed stepped structures with geometries similar (i.e., height to wavelength ratios) to stepped features found in natural mountain streams. Channel slope partially controlled bedform geometry (wavelength and height), and bedform height weakly controlled individual step spacing, but there was no relation between wavelength and grain size (D[sub 90] ).L'identification et la définition géométrique de formes de lits de rivières individuels en cascades et en paliers d'accalmie sont étudiées dans le crique Mosquito, un ruisseau de montagne, abrupte et coulant sur un sol à grain grossier, en mettant à l'essai quatre techniques analytiques : l'identification visuelle, le passage par zéro, la différenciation de la forme du lit et une analyse spectrale de puissance. Ce test constitue la première utilisation de ces techniques dans un ruisseau d'amont et l'analyse de deux profils de lits a démontré que l'identification visuelle pouvait (i) identifier, (ii) déterminer la géométrie et (iii) classifier le type individuel de lit de rivière mieux que les autres méthodes. Les autres techniques ne permettaient pas de différencier entre les paliers d'accalmie et les cascades; de plus, la grande étendue des granulométries et de hauteurs de lits entravaient leur capacité d'identifier avec constance les formes de lits à paliers. Dans le crique Mosquito, la morphologie des paliers d'accalmie (des marches accentuées qui enjambent le chenal alternant avec des bassins calmes qui enjambent le chenal) et des cascades (des structures à plusieurs niveaux qui enjambent partiellement le chenal) s'est formée au cours des 20 dernières années alors que l'action de l'eau a restructuré son ancien lit planaire, artificiel et tapissé. Le lit du chenal montre une régularité morphologique que l'analyse spectrale de puissance a interprétée comme des fluctuations périodiques des profils du lit avec des longueurs d'onde moyennes légèrement supérieures à celles identifiées par les autres méthodes. De plus, la réorganisation active du revêtement a formé des structures en paliers dont les géométries (c.-à-d. les rapports de la hauteur sur la longueur d'onde) sont semblables aux caractéristiques des paliers trouvés dans les ruisseaux de montagne naturels. La pente du chenal a contrôlé en partie la géométrie de la forme du lit (longueur d'onde et hauteur) et la hauteur de la forme du lit a faiblement contrôlé l'espacement des gradins individuels mais il n'y avait aucune relation entre la longueur d'onde et la granulométrie (D[sub 90] ).[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]
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- 2002
- Full Text
- View/download PDF
39. Holocene eruptive history of Mount Baker, Washington.
- Author
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Kovanen, D J, Easterbrook, D J, and Thomas, P A
- Subjects
CARBON isotopes ,LAHARS ,MUDFLOWS ,MOUNTAINS ,LANDFORMS - Abstract
New radiocarbon dates associated with volcanic ashes and lahars improve our understanding of the volcanic activity of Mount Baker, a 3284 m-high, andesitic stratovolcano in the North Cascades, Washington. The geologic record shows that during the Holocene, four ashes and at least seven lahars were deposited on the flanks of Mount Baker and in the nearby North Cascades. Here, we document the ages of three previously undated ashes, the Schriebers Meadow scoria, the Rocky Creek ash, and the Cathedral Crag ash. Because Mount Baker lies at the head of the Nooksack drainage, eruptive activity may influence areas downstream. Understanding the timing and characteristics of volcanic eruptions from Mount Baker is useful from volcanic hazard and paleoclimatological perspectives.De nouvelles datations au radiocarbone pour des cendres et des lahars volcaniques améliorent notre compréhension de l'activité volcanique du mont Baker, un strato-volcan andésitique d'une hauteur de 3284 mètres situé dans les Cascades septentrionales, dans l'état de Washington. Les données géologiques indiquent que durant l'Holocène quatre émissions de cendres et d'au moins sept lahars se sont déposés sur les flancs du mont Baker et dans les Cascades septentrionales environnantes. Ici, nous documentons les âges de trois cendres non datées, soit la scorie Schriebers Meadow, la cendre Rocky Creek et la cendre Cathedral Crag. Puisque le mont Baker est à la tête du bassin de drainage Nooksack, l'activité éruptive peut affecter les régions en aval. Pour bien saisir le danger volcanique et les paléoclimats, il est utile de comprendre les séquences et les caractéristiques des éruptions volcaniques du mont Baker.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]
- Published
- 2001
- Full Text
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40. The interplay of regional structure and emplacement mechanisms at the contact of the South Mountain Batholith, Nova Scotia: floor-down or wall-up?
- Author
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Culshaw, Nicholas and Bhatnagar, Pradeep
- Subjects
MOUNTAINS ,LANDFORMS ,SEDIMENTARY rocks ,GEOLOGY - Abstract
In southern Nova Scotia, the Devonian South Mountain Batholith was emplaced into metasedimentary rocks of the Cambro-Ordovician Meguma Group at ca. 370 Ma. The contact of the eastern end of the South Mountain Batholith transects at a high angle the trace of subhorizontal, upright Acadian (mid-late Devonian) folds formed in the Meguma Group. At two locations, where the contact is well exposed, there are contrasting structures in the country rocks adjacent to Acadian anticlinoria and synclinoria, respectively. Regional folds are affected by ductile deformation where anticlinoria abut the batholith but are undisturbed at the synclinoria. At the anticlinorial contacts, the metasedimentary bedding youngs towards the granite, and granite side-down shear resulted in a belt in which bedding is transposed to a new contact-parallel fabric. Deflection of linear structures that were initially horizontal in the Acadian folds (e.g., intersection lineations) illustrates the granite side-down shear. The reorientation of initially horizontal linear structures gradually diminishes as the contact is followed from the anticlinoria to the synclinoria, where the regional fold geometry is preserved right up to the contact, showing that there is no granite side-down shear in the synclinoria at the present level of erosion. Two models that potentially explain this variation in contact structure are discussed. In the first, it is explained as an artifact of emplacement of the batholith late in the growth of the Acadian folds, in which the horizontal, upright anticlinoria amplified and moved upward relative to the pluton. A shear zone was formed parallel to the contact along the thermally softened tip of the anticlinoria. The synclinoria remained fixed vertically and there was no differential movement between granite and country rock. Thus, regional structures and evidence for stoping are most widely preserved in the synclinoria, where they were not overprinted by the marginal shearing. The second model invokes floor-down emplacement of magma into folds of layered sediments with contrasting mechanical properties. The erosion surface within the synclinoria intersects slates of the Halifax Formation with mechanical properties that favour emplacement predominantly by dyking and stoping. Below the level of erosion, the stratigraphically underlying Goldenville Formation, having different mechanical properties than the Halifax, presumably is displaced downwards predominantly by ductile deformation (pure and simple shear). Within the anticlinoria, where the Goldenville Formation is exposed, the requirement of a level pluton floor necessitates that downward deflection is accompanied by relatively high ductile strains in the wall rock. A third possible model that combines features of the syntectonic and floor-down models is an obvious option.Au sud de la Nouvelle-Écosse, le batholite de South Mountain (Dévonien) a été mis en place dans des roches métasédimentaires du Groupe de Meguma (Cambro-ordovicien) il y a environ 370 Ma. Le contact entre l'extrémité est du batholite de South Mountain recoupe, selon un angle élevé, la trace des plis acadiens (Dévonien moyen à tardif) sub-horizontaux et droits formés dans le Groupe de Meguma. À deux endroits, là où le contact affleure bien, il y a des structures contrastantes dans les roches encaissantes respectivement adjacentes aux anticlinoriums et synclinoriums acadiens. Les plis régionaux sont affectés par des déformations ductiles là où les anticlinoriums se butent contre le batholite mais ils ne sont pas perturbés à l'endroit des synclinoriums. Aux contacts des anticlinoriums, le litage métasédimentaire est plus jeune vers le granite et du cisaillement vers le bas du coté du granite a donné une ceinture dans laquelle le litage est transposé en une nouvelle texture parallèle au contact. La déflection de structures linéaires, qui étaient initialement horizontales dans les plis acadiens (par ex. des intersections linéaires), montre le cisaillement dans lequel le granite est vers le bas. La réorientation des structures initialement horizontales et linéaires diminue graduellement au fur et à mesure que l'on suit le contact des anticlinoriums vers les synclinoriums, là où la géométrie des plis régionaux est préservée jusqu'au contact, montrant qu'il n'y a pas de cisaillement vers le bas du granite dans les synclinoriums au niveau actuel d'érosion. Deux modèles sont présentés qui expliquent potentiellement cette variation de la structure de contact. Dans le premier modèle, on l'explique comme une altération artificielle de la mise en place du batholite tard dans la croissance des plis acadiens, dans lesquels les anticlinoriums horizontaux et droits ont été amplifiés et déplacés vers le haut par rapport au pluton. Une zone de cisaillement a été formée parallèlement au contact le long du sommet amolli thermiquement des anticlinoriums. Les synclinoriums sont restés fixés verticalement et il n'y a pas eu de mouvement différentiel entre le granite et la roche encaissante. Ainsi, les structures régionales et les évidences d'assimilation magmatique sont généralement préservées dans les synclinoriums où elles n'ont pas été surimprimées par le cisaillement à la bordure. Le second modèle rappelle la mise en place « plancher vers le bas » du magma dans des plis de couches de sédiments ayant des propriétés mécaniques différentes. La surface d'érosion à l'intérieur des synclinoriums recoupe des schistes ardoisiers de la Formation de Halifax dont les propriétés mécaniques favorisent une mise en place surtout par des dykes et de l'assimilation magmatique. Sous le niveau d'érosion, la Formation de Goldenville sous-jacente, dont les propriétés mécaniques diffèrent de celles de la Formation de Halifax, aurait été déplacée vers le bas surtout par déformation ductile (tout simplement du cisaillement). À l'intérieur des anticlinoriums, là où affleure la Formation de Goldenville, la nécessité d'une surface plane pour le pluton exige que la déflection vers le bas soit accompagnée par des contraintes ductiles relativement élevées dans la roche encaissante. Une autre option évidente serait la possibilité d'un troisième modèle combinant des caractéristiques des modèles syntectoniques et de « plancher vers le bas ».[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]
- Published
- 2001
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41. Paleomagnetism of the Quottoon plutonic complex in the Coast Mountains of British Columbia and southeastern Alaska: evidence for tilting during uplift.
- Author
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Butler, Robert F, Gehrels, George E, Crawford, Maria Luisa, and Crawford, William A
- Subjects
PALEOMAGNETISM ,MOUNTAINS ,LANDFORMS - Abstract
The Quottoon plutonic complex (part of the great tonalite sill) was emplaced into eastern parts of the Coast shear zone along the west flank of the Coast Mountains. U–Pb crystallization ages range from 72.3 to 55.5 Ma. A regional compilation of K–Ar hornblende dates from the tonalite sill indicates a west to east decrease from ~60 Ma to ~54 Ma across the intrusive suite. Paleomagnetic samples were collected at 160 sites (
8 samples per site) along six transects across the Quottoon complex between the Skeena River and Willard Inlet. Directions of characteristic remanent magnetization (ChRM) were successfully determined by principal component analysis of thermal demagnetization data for about half of the samples collected. Site-mean ChRM directions were determined for 56 sites from the Skeena River, Quottoon Inlet, Steamer Passage, and Wales Island transects, using criteria of
4 sample ChRM directions per site and 95% confidence limit (α[sub 95] )
25°. For Filmore Island and Willard Inlet, few sites provided adequate determinations of site-mean ChRM directions, but many sample ChRM directions were well determined and consistent. The mean direction from the Skeena River – Quottoon Inlet collection is nearly concordant with the expected Eocene direction. Mean directions from other transects have clockwise-rotated declinations and inclinations that are shallower than the expected direction by up to 23°. Consistent with expectations for east-side-up tilting of crustal panels, sites from the western part of each transect have mean directions farther from the Eocene expected direction than do sites from the eastern part of the transect. The magnitude of east-side-up tilt varies along strike: the Skeena River to Quottoon Inlet segment experienced little or no tilt; Steamer Passage south of Portland Inlet records 15° tilt; north of Portland Inlet, tilts are 40° for Wales Island and 35° for Filmore Island; farther north, tilt decreases to 12° for Willard Inlet. Tilting was driven by Eocene extension of the Coast Mountains, with tilted crustal panels bounded by northwest-striking, east-side-down normal faults and northeast-striking transfer faults or shear zones. The ACCRETE seismic transect imaged east-dipping reflectors down to ~15 km depth, which likely correspond to the east-side-down normal faults. The most significant of the northeast-striking transfer structures must underlie Portland Inlet. Based on a tilting domino model, about 30% extension is required to produce the 40° tilt of crustal blocks at Wales and Filmore islands.Le complexe plutonique Quottoon (une partie du grand filon-couche de tonalite) a été mis en place dans des parties orientales de la zone de cisaillement côtière le long du flanc ouest de la chaîne Côtière. Des âges de cristallisation U–Pb vont de 72,3 à 55,5 Ma. Une compilation régionale de datations K–Ar sur des hornblendes provenant du filon-couche de tonalite indique une décroissance d'ouest en est à travers la suite intrusive de ~60 Ma à ~54 Ma. Des échantillons paléomagnétiques ont été recueillis sur 160 sites (
8 échantillons par site) le long de six transects à travers le complexe de Quottoon, entre la rivière Skeena et l'inlet Willard. Pour environ la moitié des échantillons recueillis, les directions du magnétisme rémanent caractéristique (ChRM) ont été déterminées avec succès par une analyse des composantes principales de la démagnétisation thermique. Les moyennes des directions ChRM ont été déterminées par site pour 56 sites situés sur les transects de la rivière Skeena, de l'inlet Quottoon, du passage Steamer et de l'île de Wales, utilisant des critères de
4 directions ChRM sur des échantillons par site et une limite de confiance de 95 % (α[sub 95] )
25º. En ce qui concerne l'île Filmore et l'inlet Willard, peu de déterminations adéquates de directions moyennes ChRM spécifiques au site ont été obtenues; cependant, plusieurs directions ChRM sur les échantillons étaient bien déterminées et cohérentes. La direction moyenne de la collecte provenant de la rivière Skeena – inlet Quottoon concorde presque avec la direction escomptée de l'Éocène. Les directions moyennes d'autres transects ont des déclinaisons et des inclinaisons à rotation de sens horaire qui sont jusqu'à 23º moins profondes que les directions escomptées. Les sites de la portion ouest de chaque transect ont des directions moyennes divergeant plus de la direction escomptée à l'Éocène que les sites de la partie est du transect, ce qui concorde avec les attentes d'un basculement du côté est vers le haut de grands blocs de la croûte. L'amplitude du basculement du côté est vers le haut varie selon la direction : le segment entre la rivière Skeena et l'inlet Quottoon n'a pas ou a peu basculé; le passage Steamer, au sud de Portland Inlet, enregistre 15º de basculement; au nord de l'inlet Portland, le basculement est de 40º pour l'île de Wales, 35º pour l'île Filmore et, plus au nord, l'inclinaison diminue à 12º pour l'inlet Willard. Le basculement provient de l'extension, à l'Éocène, de la chaîne Côtière au moyen de grands blocs inclinés de la croûte limités par des failles normales à direction nord-ouest et le côté est vers le bas et par des failles de transfert ou des zones de cisaillement à direction nord-est. Le transect sismique « ACCRETE » a interprété des réflecteurs à pendage est jusqu'à ~15 km de profond qui correspondent probablement au failles normales à côté est vers le bas. La plus importante des structures de transfert à direction nord-est doit se trouver sous l'inlet Portland. Selon une théorie de basculement de dominos, il faut une extension de 30 % pour basculer de 40º les blocs de la croûte aux îles de Wales et de Filmore.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]
- Published
- 2001
- Full Text
- View/download PDF
42. Holocene and latest Pleistocene fluctuations of Stutfield Glacier, Canadian Rockies.
- Author
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Osborn, G D, Robinson, B J, and Luckman, B H
- Subjects
GLACIERS ,MOUNTAINS ,MORAINES ,GLACIAL landforms ,RIVERS - Abstract
The Holocene and late glacial history of fluctuations of Stutfield Glacier are reconstructed using moraine stratigraphy, tephrochronology, and dendroglaciology. Stratigraphic sections in the lateral moraines contain tills from at least three glacier advances separated by volcanic tephras and paleosols. The oldest, pre-Mazama till is correlated with the Crowfoot Advance (dated elsewhere to be Younger Dryas equivalent). A Neoglacial till is found between the Mazama tephra and a paleosol developed on the Bridge River tephra. A log dating 2400 BP from the upper part of this till indicates that this glacier advance, correlated with the Peyto Advance, culminated shortly before deposition of the Bridge River tephra. Radiocarbon and tree-ring dates from overridden trees exposed in moraine sections indicate that the initial Cavell (Little Ice Age (LIA)) Advance overrode this paleosol and trees after A.D. 1271. Three subsequent phases of the Cavell Advance were dated by dendrochronology. The maximum glacier extent occurred in the mid-18th century, predating 1743 on the southern lateral, although ice still occupied and tilted a tree on the north lateral in 1758. Subsequent glacier advances occurred ca. 1800–1816 and in the late 19th century. The relative extent of the LIA advances at Stutfield differs from that of other major eastward flowing outlets of the Columbia Icefield, which have maxima in the mid–late 19th century. This is the first study from the Canadian Rockies to demonstrate that the large, morphologically simple, lateral moraines defining the LIA glacier limits are actually composite features, built up progressively (but discontinuously) over the Holocene and contain evidence of multiple Holocene- and Crowfoot-age glacier advances.La stratigraphie des moraines, la téphrochronologie et la dendroglaciologie des moraines ont servi à reconstruire les fluctuations à l'Holocène et au cours de l'histoire glaciaire tardive du glacier Stutfield. Les sections stratigraphiques dans les moraines latérales contiennent des tills d'au moins trois avancées glaciaires séparées par des tephras volcaniques et des paléosols. Le plus ancien, le till pré-Mazama, est corrélé à l'avancée Crowfoot (dont on a déterminé l'âge ailleurs comme étant un équivalent du Dryas récent). Un till de l'époque néo-glaciaire se retrouve entre le tephra Mazama et un paléosol développé sur le tephra de Bridge River. Un billot, daté 2400 BP, provenant de la partie supérieure de ce till, indique que cette avancée glaciaire, corrélée à l'avancée de Peyto, a culminé peu de temps avant la déposition du tephra de Bridge River. Des datations au [sup 14] C et des séries chronlogiques provenant d'arbres recouverts, puis exposés dans des sections de moraine, indiquent que l'avancée Cavell initiale (petit âge glaciaire) a chevauché ce paléosol et les arbres après l'an 1271. La dendrochronologie a permis la datation de trois phases subséquentes de l'avancée Cavell. L'étendue glaciaire maximale eut lieu au milieu du 18e siècle, avant 1743 sur le coté sud bien que la glace fut encore présente sur le côté nord et y ait basculé un arbre en 1758. Des avancées glaciaires subséquentes ont eu lieu vers 1800-1816 et vers la fin du 19e siècle. L'étendue relative des avancées du petit âge glaciaire à Stutfield diffère de celles d'autres glaciers majeurs du champ de glace Columbia s'écoulant vers l'est et qui ont eu leur maximum dans la deuxième moitié du 19e siècle. Cette étude est la première provenant des Rocheuses canadiennes à démonter que les grandes moraines latérales morphologiquement simples définissant les limites du glacier au petit âge glaciaire sont en fait des éléments composites, développés progressivement (mais de façon discontinue) tout au cours de l'Holocène et qu'elles contiennent des évidences d'avancées glaciaires multiples d'âge Holocène et Crowfoot.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]
- Published
- 2001
- Full Text
- View/download PDF
43. Late Neoproterozoic cap carbonates: Mackenzie Mountains, northwestern Canada: precipitation and global glacial meltdown.
- Author
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James, Noel P, Narbonne, Guy M, and Kyser, T Kurtis
- Subjects
CARBONATES ,MOUNTAINS ,LANDFORMS ,ROCKS - Abstract
The 3-27 m-thick cap carbonate overlying "Marinoan" Ice Brook Formation glacigene sediments and Keele Formation carbonate and terrigenous clastic rocks consists of two distinctive stratigraphic units. A lower, splintery, buff-weathering, microcrystalline dolostone of extensive lateral uniformity comprises mm-laminated peloidal sediment with local, low-angle, hummocky-like cross-stratification, micro-ridges, and synsedimentary tepees, all elongated perpendicular to depositional strike. This dolostone is unconformably overlain by an upper limestone that exhibits pronounced facies variation from inboard peloidal lime grainstone and mudstone to shelf-edge cementstone to outboard lime wackestone and mudstone. Calcite cementstones range from isolated crystal fans in laminated limestone to huge, decimetre-scale crystal arrays, to hemispherical and elongate crystal stromatolites wholly composed of acicular crystals that form decametre-scale reeflike structures. Crystal stromatolites are precipitates and replaced microbiolites that constructed biostromes and bioherms, like those on many flat-topped, reef-rimmed platforms. The calcite crystals have all the physical and chemical attributes of neomorphosed aragonite. This aragonite extensively replaced sediment and microbiolite just below the sea floor and grew upward into the overlying water column. Such interpreted massive synsedimentary replacement is rare in geological history and attests to the highly saturated state of the immediate postglacial ocean. All sediment is interpreted to have been CaCO[sub 3] originally. Low and constant δ[sup 18] O values reflect diagenetic modification of these carbonates, although chemical attributes, such as Sr and C isotopes in some lithologies, are near pristine. Lower dolostones, virtually identical to most other coeval Marinoan caps worldwide, were part of a global precipitation event of remarkable similarity. Upper limestones are a more local phenomenon, deposited during sea-level rise in an aragonitic sea returning to equilibrium after global glaciation. Low [sup 87] Sr/[sup 86] Sr ratios and varying δ[sup 13] C values with carbonate sedimentary facies indicate that both units must have formed relatively rapidly, prior to significant fluvioglacial runoff, or that the influence of this runoff on the chemistry of seawater along continental shelves was minimal. The cap carbonate is thus interpreted to have formed in two steps: (1) during initial marine ice melting accompanied by oceanic overturn and upwelling, preceding continental margin rebound, and (2) during initial stages of sea-level rise accompanying continental deglaciation. While confirming brief, but extensive, carbonate precipitation from an ocean highly perturbed by global glaciation, the rocks also suggest that this event did not permanently affect either late Neoproterozoic ocean chemistry or the contained marine biosphere.La couche de carbonate de 3 à 27 mètres d'épaisseur chapeautant les sédiments glaciogènes « Marinoën » de la Formation Ice Brook ainsi que les carbonates et les roches clastiques terrigènes de la Formation Keele comporte deux unités stratigraphiques distinctes. Une dolomie inférieure, à éclats, microcristalline, à grande uniformité latérale et dont l'altération est de couleur chamois, comprend des sédiments péloïdes à laminations millimétriques et, par endroits, des stratifications croisées, à angle faible et mamelonnées, ainsi que des micro-crêtes et des tipis synsédimentaires, tous allongés perpendiculairement à la direction de la déposition. Un calcaire supérieur repose en discordance sur cette dolomie; le calcaire montre des variations de faciès prononcées variant de mudstone et grainstone calcareux intérieurs péloïdes, à des wackestones et des mudstones extérieurs calcareux en passant par des calcaires argileux cimentés du bord de plate-forme. Les calcaires argileux à calcite varient de cristaux isolés dans des calcaires laminés à d'immenses réseaux de cristaux d'échelle décimétrique et jusqu'à des stromatolithes de cristaux hémisphériques et allongés, composés entièrement de cristaux aciculaires qui forment des structures de type récifales à échelle décamétrique. Les stromatolithes à cristaux se sont substitués aux microbiolites et ont édifié des biostromes et des biohermes comme on peut le voir sur de nombreuses plate-formes à surface plane, entourées de récifs. Les cristaux de calcite ont tous les attributs physiques et chimiques d'une aragonite néoformée. Cette aragonite a remplacé de façon extensive les sédiments et la microbiolite tout juste sous le fond marin et a crû vers le haut dans la colonne d'eau sus-jacente. Un tel remplacement synsédimentaire si vaste est rare dans l'histoire géologique et cela atteste de la grande saturation de l'océan post-glacial environnant. Nos données confirment que tous les sédiments étaient du CaCO[sub 3] à l'origine. Des valeurs δ[sup 18] O basses et constantes démontrent la modification diagénétique de ces carbonates, bien que des attributs chimiques tels que des isotopes du Sr et du C sont presque dans leur état originel dans certaines lithologies. Des dolomies inférieures, virtuellement identiques à la plupart des roches couvertures Marinoën à travers le monde, faisaient partie d'un événement de précipitation global à similarité remarquable. Les calcaires supérieurs représentent un phénomène plus local, ils se sont déposés lors d'une élévation du niveau de la mer dans une mer aragonitique qui retrouvait son équilibre après une glaciation globale. Les rapports [sup 87] Sr/[sup 86] Sr et des valeurs δ[sup 13] O variables selon le faciès sédimentaire à carbonate indiquent que les deux unités ont dû se former relativement rapidement, avant un ruissellement fluvio-glaciaire significatif, ou que l'influence de ce ruissellement sur la chimie de l'eau de mer le long des plates-formes continentales était minimale. La roche couverture de carbonate se serait donc formée en deux étapes. (1) au cours de la fonte initiale de la glace marine accompagnée d'un renversement océanique et d'une remontée d'eau, avant le relèvement de la marge continentale, et (2) au cours des étapes initiales de remontée du niveau de la mer lors de la déglaciation du continent. Alors qu'elles confirment une précipitation brève mais extensive de carbonate d'un océan hautement perturbé par la glaciation globale, les roches présenteraient aussi des évidences que cet événement n'a pas affecté de façon permanente la chimie de l'océan néoprotérozoïque tardif ni la biosphère marine qui s'y trouvait.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]
- Published
- 2001
- Full Text
- View/download PDF
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