Search

Aagard, Troels Aitken, Alec Akoglu, Ahmet Allard, Michel Ansdell, Kevin Archibald, Donnelly Arnaud, Emmanuelle Atkinson, Gail Averianov, Alexander Azizi, Hossain Baird, Graham Barendregt, Rene Barr, Sandra Bauer, Bernard Bedard, Jean [...]

The Canadian Journal of Earth Sciences 'Best Paper Award' is an annual award given jointly by Canadian Science Publishing (CSP) and the Geological Association of Canada (GAC). It reflects the [...]

On May 25, 2009, at the annual Geological Association of Canada luncheon, the first winner of the GAC--NRC Research Press, Canadian Journal of Earth Sciences Best Paper Award was announced. [...]

The Canadian Journal of Earth Sciences 'Best Paper Award' is an annual award given jointly by Canadian Science Publishing (CSP) and the Geological Association of Canada. It reflects the Geological [...]

The Canadian Journal of Earth Sciences 'Best Paper Award' is an annual award given jointly by Canadian Science Publishing (CSP) and the Geological Association of Canada. It reflects the Geological [...]

It is a pleasure to announce the winner of the prestigious 2011 GAC-CSP Canadian Journal of Earth Sciences Best Paper Award. D.E. Moser, C.L. Cupelli, I.R. Barker, R.M. Flowers, J.R. [...]

The article announces that the GAC–CSP Canadian Journal of Earth Sciences Best Paper Award for 2016 has been presented to Richard A. Glen and colleagues for their study related to different styles of non-collisional orogens and implications for crustal growth.

The article announces the selection of "Chronostratigraphy of the Hottah Terrane and Great Bear Magmatic Zone of Wopmay Orogen, Canada and Exploration of a Terrane Translation Model" by Luke Ootes et al. as the winner of the 2015 "Canadian Journal of Earth Sciences" Best Paper Award.

Introduces a series of articles regarding the impact of the mass extinction of rare and exotic species on global environment and evolution, published in the 1999 issue "Canadian Journal of Earth Sciences."

Canada ratified the United Nations Convention on the Law of the Sea (UNCLOS) in 2003. With that ratification is an obligation to submit data and information to the U.N. pertaining to the limits of the country's extended continental shelf (ECS); the portion of the juridical continental shelf that extends beyond 200 nautical miles. A team of Canadian scientists, managers, and legal experts that included representation from three Federal Departments (Natural Resources Canada, Fisheries and Oceans Canada, and Global Affairs Canada) with additional support from other departments, spent 13 years compiling and acquiring data to provide the scientific evidence to support delineation of Canada's seaward most maritime limit. The submission has the potential to provide Canada with 2.4 million km (2) of additional submarine landmass in the Atlantic and the Arctic oceans over which Canada exercises sovereign rights for the purpose of exploring and exploiting its natural resources. Specific information such as the tectonic framework of the continental margin, the geomorphology of the margin and in particular the continental slope, the geologic nature of adjoined ridges, rises, and plateaux, and sediment thickness within adjacent basins are examples of fundamental pieces of geoscientific information needed to substantiate Canada's outermost maritime limits. This paper highlights a number of segments of Canada's continental margins to showcase this scientific evidence and how it is applied in the UNCLOS context. In doing so, the paper demonstrates the geologic complexity of Canada's margins as illustrated in scientific publications that have resulted from these new data collections, while at the same time presenting new scientific evidence and interpretations. This collection of data and information provides a wealth of new knowledge in Canada's offshore regions. The massive data compilation in the Atlantic led to conception of continental margins, in a source-to-sink scenario, as having an equilibrium base level or graded form, comparable to river systems. Departures from this shape relate to the interplay of sedimentary processes and in particular to those processes that do not fit the source-to-sink paradigm. For example, a significant part of the Atlantic margin is shown to be heavily influenced by along-slope geostrophic currents that generated massive contourite drift deposits. These deposits reflect lateral transport of sediment that had a significant impact on the morphology of the margin. The role of mass transport processes in shaping continental margins is also highlighted, and in particular the collapses of entire segments of the margin were observed. The prominent role mass failure processes play in delivering sediment to the adjacent abyssal plain is also critical in the ECS context. These observations challenge the entrenched notion of a continental margin comprising a shelf, slope, and rise and in particular the concept of the 'continental rise'. Prior to 2006, regions of the Arctic Ocean seaward of the Canadian landmass had fewer than 5000 km of seismic reflection data. The massive efforts of Arctic coastal States to map their margins for ECS purposes have led to a leap in technological advances to acquire data in ice-covered seas and have led to a wealth of new geoscientific knowledge. Perhaps foremost amongst this knowledge is demonstration that Canada Basin is indeed a fully developed ocean basin, albeit significantly infilled with sediment. Based on this knowledge and identification of related structures, new realistic tectonic scenarios for opening of the Amerasia Basin are proposed that include a significant component of transform or strike-slip motions. With seismic velocity and rock sample information, the continental nature of Alpha and Mendeleev ridges has been substantiated. Even bathymetric data were lacking in the Arctic and new editions of seafloor maps now support grids of 500 m spacing; although some regions remain sparse. Once thought to be relatively stagnant, sedimentary processes such as found in many ocean basins were discovered in the Arctic Ocean. Evidence of geostrophic currents, sediment mass failures, and deep-sea turbidity current channels were found to be ubiquitous, even in the deepest parts of the Arctic's basins. Key words: United Nations Convention on the Law of the Sea, extended continental shelf, continental margin, Atlantic Ocean, Arctic Ocean, 1. Introduction It is a common adage that we know more about the Moon and Mars than we do about the oceans on Earth. As an example, according to the [...]

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.)

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.)

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.)

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.)

High-resolution topographic modeling has become more accessible due to the development of structure from motion (SfM)-image-matching algorithms in digital photogrammetry. Large archival databases of historical aerial photographs are available in university, public, and government libraries, commonly as paper copies. The photographs can be in poor condition (i.e., deformed by humidity, scratched, or annotated). In addition, the negatives, as well as metadata, may be missing. Processing such photographs using classic stereo-photogrammetry is difficult and, in many instances, impossible. SfM can be applied to these photosets to access the valuable archive of geomorphic changes over the past century. In this paper, we illustrate the utility of the SfM technique using 568 digitized vertical aerial photographs of Mount Meager volcano, located in southwestern British Columbia, Canada. We use the aerial photographs, which span the period from 1947 to 2006, to track glaciers and glacier-landslide interactions on the volcano. Over this period, glaciers have thinned and retreated, interrupted by minor advances in the 1960s and 1970s. Landslides are frequent on the volcano and contribute to debris cover on the glaciers affecting the ablation process. SfM processing of the aerial photographs allowed us to unlock geomorphic information and reconstruct landscape change that would otherwise have been impossible. The results from SfM provide a visually effective way of presenting landscape change to a broad public audience, as a form of virtual geoheritage. The approach can thus be broadly applied in scientific and professional practices for improving land planning and hazard management. Key words: historical aerial photographs, structure from motion, glacier change, landslides, debris-covered glaciers. La modelisation topographique de haute resolution est devenue plus accessible en raison du developpement d'algorithmes de jumelage d'images de type << structure from motion >> (SfM, structure acquise a partir d'un mouvement) en photogrammetrie numerique. D'imposantes bases de donnees d'archives de photographies aeriennes sont disponibles dans les bibliotheques universitaires, publiques et gouvernementales, generalement en version papier. Ces photographies peuvent etre en mauvais etat (c.-a-d., deformees par l'humidite, egratignees ou annotees). En outre, des negatifs, ainsi que des metadonnees, peuvent manquer a l'appel. Le traitement de telles photographies par stereophoto-grammetrie classique est difficile, voire impossible dans bien des cas. La SfM peut etre appliquee a ses ensembles de photos pour acceder a l'important registre de changements geomorphologiques durant le siecle passe qu'ils renferment. Nous illustrons l'utilisation de la methode SfM en utilisant 568 photographies aeriennes verticales numerisees du volcan du mont Meager, dans le sud-ouest de la Colombie-Britannique (Canada). Nous utilisons les photographies aeriennes, qui couvrent la periode de 1947 a 2006, pour suivre les glaciers et les interactions entre glaciers et glissements de terrain sur le volcan. Cette periode est marquee par l'amincissement et le retrait des glaciers, interrompus par des avancees mineures dans les annees 1960 et 1970. Les glissements de terrain sont frequents sur le volcan et participent a l'accumulation d'un couvert de debris sur les glaciers qui influence le processus d'ablation. Le traitement SfM des photographies aeriennes nous a permis d'extraire de l'information geomorphologique et de reconstituer les changements du paysage, ce qui n'aurait pas ete possible autrement. Les resultats de SfM offrent un moyen visuellement efficace de presenter des modifications du paysage au grand public, comme geopatrimoine virtuel. L'approche peut ainsi etre appliquee largement dans les domaines scientifique et professionnel pour ameliorer l'amenagement du territoire et la gestion des risques. [Traduit par la Redaction] Mots-cles : photographies aeriennes passees, << structure from motion >>, modification de glaciers, glissements de terrain, glaciers couverts de debris., Introduction Reconstructions of geomorphic change over time are fundamental in many landform and natural hazard studies. Such landscape reconstructions are essential for following the evolution of features that might cause [...]

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.)

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.)

Dale Russell described the osteology, morphology, and ecology of the small theropod 'Stenonychosaurus inequalis' in two papers, speculating on its life habits, brain power, vision, movement, feeding, and hand capabilities. Russell even pondered a tool-using dinosauroid, the hypothetical troodontid descendant if the lineage had survived the Cretaceous-Paleogene extinction event. We revisit the life habits of the North American troodontids Troodon formosus and Latenivenatrix mcmasterae in part by reviewing various trace fossils of T. formosus discovered in Montana. These fossils include egg clutches, a nest, and recently discovered regurgitalites. We also contemplate the possibility of dinosaur tool use. Troodon likely constructed earthen nests in the same way that ratites and other birds did to create their nesting scrapes through backward hindlimb kicks. The more complex clutch architecture suggests dexterous movement of the eggs, potentially requiring manual manipulation. Functionally, reproductive traces support elevated body temperatures and a metabolic output that approach but do not equal that of modern birds. Brooding would require very high energy investment from the adult. The regurgitalites largely contain multi-individual aggregations of the marsupialiform Alphadon and support Russell's hypotheses of troodontids as crepuscular to nocturnal, intelligent, small game hunters with elevated metabolism and enhanced vision. Tool use in a few crocodilians and widely among extant birds suggests a reasonable possibility of this behavior in nonavian dinosaurs. Whether an avian-comparable encephalization quotient and freed forelimbs would make North American troodontids good candidates for exhibiting such behavior remains an open and speculative question. However, given the minimal modification made to tools by modern archosaurs, recognition of fossil tools poses a challenging problem. Key words: Troodon, troodontid, reproduction, encephalization quotient, regurgitalites, gastric pellets, trace fossils, tool use, physiology. Dale Russell a decrit l'osteologie, la morphologie et l'ecologie du petit theropode [much less than] Stenonychosaurus inequalis [much greater than] dans deux articles, emettant des hypotheses sur ses habitudes de vie, ses capacites cerebrales, sa vision, ses deplacements, son alimentation et sa dexterite. Il a meme envisage un dinosauroide se servant d'outils, ledescendant hypothetiquede troodontides, si cette lignee devait avoir survecu a l'extinction du Cretace-Paleogene. Nous reexaminons les habitudes de vie des troodontides nord-americains Troodon formosus et Latenivenatrix mcmasterae en partie par l'examen de differents ichnofossiles de T. formosus decouverts au Montana. Ceux-ci comprennent des pontes, un nid et des regurgitalites decouvertes recemment. Nous considerons egalement la possibilite d'utilisation d'outils par des dinosaures. Les Troodon construisaient vraisemblablement des nids de terre a l'instar de ratites ou autres oiseaux qui font leurs nids en creusant la terre par des coups de leurs membres posterieurs vers l'arriere. L'architecture complexe des pontes semble indiquer une grande dexterite pour deplacer les ceufs, necessitant potentiellement une manipulation manuelle. Du point de vue fonctionnel, les ichnofossiles associes a la reproduction appuient l'interpretation de temperatures elevees du corps et d'un metabolisme s'approchant de celui des oiseaux modernes, sans toutefois l'egaler. La couvaison aurait requis un tres grand investissement energetique des adultes. Les regurgitalites contiennent principalement des agregations de restes de plusieurs individus du marsupialiforme Alphadon et appuient les hypotheses de Dale Russell selon lesquelles les troodontides etaient des chasseurs crepusculaires a nocturnes et intelligents de petit gibier caracterises par un metabolisme eleve et une excellente vue. L'utilisation d'outils chez quelques crocodiliens et tres repandue chez les oiseaux actuels laisse entrevoir une possibilite raisonnable d'un tel comportement chez des dinosaures non aviens. La question a savoir si un quotient d'encephalisation semblable a celui des oiseaux et des membres anterieurs liberes pourraient faire des troodontides nord-americains des bons candidats pour presenter un tel comportement demeure ouverte et hypothetique. Etant donne le peu de modifications apportees aux outils par les archosaures modernes, la reconnaissance d'outils fossiles constitue un defi problematique. [Traduit par la Redaction] Mots-cles: Troodon, troodontides, reproduction, quotient d'encephalisation, regurgitalites, boulettes gastriques, ichnofossiles, utilisation d'outils, physiologie., Introduction Dale Russell summarized the osteology, morphology, and ecology of the troodontid dinosaur 'Stenonychosaurus inequalis' in two papers (Russell 1969; Russell and Seguin 1982). In the first paper, Russell (1969) [...]

A preface to the journal "Canadian Journal of Earth Sciences" (CJES) Lithoprobe Special Issues 1 and 2 is presented.

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.)

This paper provides an integrated field and geochemical study of weakly alkalic, ~360 Ma mafic rocks from the Yukon–Tanana terrane in the Finlayson Lake region, southeastern Yukon. These mafic rocks occur as dykes and sills that crosscut older felsic metavolcanic rocks and metasedimentary rocks (Kudz Ze Kayah unit) or as flows interlayered with carbonaceous metasedimentary rocks. The mafic rocks have signatures similar to those of ocean-island basalts, moderate TiO[sub 2] and P[sub 2] O[sub 5] contents, elevated high field strength element and light rare earth element contents, and ℇNd[sub 350] = +1.1. A subset of the dykes (group 4b) has similar geochemical characteristics but with higher Th/Nb and lower Nb/U ratios, higher Zr and light rare earth element contents, and ℇNd[sub 350] = –2.8. The geochemical and isotopic attributes of these rocks are consistent with formation from either lithospheric or asthenospheric sources during decompression melting of the mantle, with some rocks exhibiting evidence for crustal contamination (group 4b). The alkalic basalts are interpreted to represent ~360 Ma ensialic back-arc rifting and basin generation. It is envisioned that east-dipping subduction, represented by slightly older magmatic suites (Fire Lake unit), was disrupted by subduction hinge roll-back, westward migration of arc magmatism, and the onset of back-arc extension. Decompression melting of the mantle associated with back-arc generation resulted in mantle melting and the formation of the alkalic basalts. The spatial association of this mafic magmatism with crustally derived felsic volcanic rocks and contained volcanogenic massive sulphide mineralization suggests that the associated deposits (Kudz Ze Kayah, GP4F) formed within an ensialic back-arc environment.Cet article présente une étude intégrée de données de terrain et de géochimie de roches mafiques, ~360 Ma, faiblement alcalines, du terrane Yukon–Tanana dans la région du lac Finlayson, dans le sud-est du Yukon. Ces roches mafiques se présentent sous forme de dykes et de filons-couches, qui recoupent des roches métavolcaniques et des roches métasédimentaires (unité Kudz Ze Kayah) plus âgées, ou sous forme de coulées interstratifiées avec des roches métasédimentaires carbonées. Les roches mafiques ont des signatures semblables à celles des basaltes d'îles océaniques, des teneurs modérées en TiO[sub 2] et P[sub 2] O[sub 5] , de hautes teneurs en éléments à champ électrostatique élevé et en éléments de terres rares légers, ainsi qu'un ℇNd[sub 350] = +1,1. Un sous-ensemble des dykes, (groupe 4b), a des caractéristiques géochimiques similaires mais avec un rapport Th/Nb plus élevé, un rapport Nb/U plus faible et une plus haute teneur en Zr et en éléments de terres rares légers, ainsi qu'une valeur de ℇNd[sub 350] = –2,8. Les caractéristiques géochimiques et isotopiques de ces roches concordent avec une formation de source lithosphérique ou asthénosphérique durant la fusion de décompression du manteau, alors que quelques roches montrent des évidences d'une contamination crustale (groupe 4b). Les basaltes alcalins représenteraient l'extension d'arrière-arc ensialique et la génération de bassins, ~360 Ma. On croit que la subduction à pendage vers l'est, représentée par des suites magmatiques légèrement plus âgées (unité Fire Lake), a été perturbée par le repositionnement de la charnière de subduction, la migration vers l'ouest du magmatisme d'arc et le début d'une extension d'arrière-arc. La fusion de décompression du manteau, associée à la génération d'arrière-arc, a conduit à la fusion du manteau et à la formation des basaltes alcalins. L'association spatiale de ce magmatisme mafique et des roches felsiques volcaniques, dérivées de la croûte, et la minéralisation de sulfures massifs volcanogènes qu'on y retrouve portent à croire que les dépôts associés (Kudz Ze Kayah, GP4F) se sont formés dans un environnement d'arrière-arc ensialique.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

While the Cardium Formation (Turonian–Coniacian, Upper Cretaceous) is one of the major hydrocarbon sources, and consequently one of the most intensely studied siliciclastic formations in the Western Canada Sedimentary Basin, it remains one of the more controversial units in terms of understanding the depositional environments and processes it represents, and correlations between subsurface and outcrop. Proposed subsurface subdivisions based on sequence stratigraphic concepts, and relation of these allomembers to long-established members of the outcrop belt, have provoked further disagreements. The general lack of biostratigraphic data within the Cardium Formation makes it difficult to test different models and to resolve conflicting proposals. This paper provides stratigraphic and taxonomic information on all known scaphitid ammonoids from the Cardium Formation and correlation of these faunas with the Turonian and Coniacian zonal scheme established in the United States Western Interior; future publications will provide similar treatments of the collignoniceratid ammonites and inoceramid bivalves.Bien que la Formation de Cardium (Turonien–Coniacien; Crétacé supérieur) soit l'une des sources majeures d'hydrocarbures et, par conséquent, l'une des formations siliciclastiques les plus intensément étudiées du bassin sédimentaire de l'Ouest canadien, elle demeure l'une des unités les plus controversées en termes de compréhension des environnements et des processus de déposition qu'elle représente et des corrélations entre le roc souterrain et les affleurements. Les subdivisions proposées pour la subsurface, basées sur des concepts de séquences stratigraphiques, et les relations de ces allomembres à des membres de la ceinture d'affleurements établis depuis longtemps ont causé de nouvelles divergences d'opinion. Le manque de données biostratigraphiques à l'intérieur de la formation complique l'essai de différents modèles et la résolution de propositions contradictoires. Cet article fournit des informations stratigraphiques et taxonomiques sur tous les Ammonoïdés scaphitidae de la Formation de Cardium ainsi qu'une corrélation de ces faunes avec le schéma zonal du Turonien et du Coniacien établi dans l'Ouest américain intérieur; des publications à venir traiteront de façon similaire des Ammonites collignoniceratidae et des bivalves Inoceramidae.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

The Esterhazy Member of the western Canada Prairie Evaporite has been mined underground for sylvite (KCl) since the early 1960s. Although the geology of the Esterhazy Member ore body is largely considered a regional flat lying continuous series of thin potash hosting beds, there are numerous occurrences where the ore has been either replaced or removed leaving behind uneconomical halite-rich sections. An explanation of the underlying controls on the formation of these salt anomalies has been somewhat elusive although the overwhelming assumption remains that these features developed in lows on a salina. This paper proposes that salt anomalies formed because of two processes, early compaction of carbonate shoals of the Winnipegosis Formation and tectonics that resulted in multiple stages of block movement during the deposition of the upper Prairie Evaporite. Since these two processes can result in a significantly different size to a salt anomaly, encountering one or the other type can have a significant effect on the economics of the ore body. This paper looks at some of the geological methods that might provide geologists with means to predicting salt anomalies. Key words: Prairie Evaporite Formation, potash mining, salt anomalies, Winnipegosis Formation. Le membre d'Esterhazy de la Formation d'evaporite des Prairies de l'Ouest canadien fait l'objet d'une exploitation souterraine pour la sylvite (KCl) depuis le debut des annees 1960. Si la geologie du membre d'Esterhazy est generalement consideree comme etant une serie generalement horizontale et continue a l'echelle regionale de minces lits contenant de la potasse, dans de nombreux endroits, le minerai a ete soit remplace ou retire, laissant des sequences riches en halite sans interet sur le plan economique. L'explication des controles qui sous-tendent la formation de ces anomalies de sel s'est averee quelque peu problematique, bien que l'hypothese dominante demeure voulant qu'elles se soient formees dans des depressions dans une salina. Le present article propose que les anomalies de sel se sont formees en raison de deux processus, soit la compaction precoce de haut-fond de carbonates de la Formation de Winnipegosis et une tectonique qui a produit differentes phases de deplacement de blocs durant le depot de la partie superieure de la Formation d'evaporite des Praires. Comme ces deux processus peuvent produire des anomalies de sel de tailles significativement differentes, le fait de rencontrer l'un ou l'autre des deux types peut avoir une importante incidence sur les parametres economiques du corps mineralise. L'article se penche sur certaines des methodes geologiques qui pourraient aider les geologues a predire les anomalies de sel. [Traduit par la Redaction] Mots-cles: Formation d'evaporite des Prairies, exploitation de la potasse, anomalies de sel, Formation de Winnipegosis., Introduction The Prairie Evaporite Formation of Saskatchewan, Canada, is a Devonian evaporite deposit of Givetian age, and a world class source of sylvite (KCl). The formative Elk Point Basin, which [...]

Subduction of the Paleo-Pacific Plate plays a key role in the Early Jurassic magmatism evolution in the Yanbian area, Northeast China. In this paper, zircon U-Pb ages, whole-rock geochemical, and Sr-Nd-Hf isotopic compositions are presented. The Early Jurassic gabbros, diorite enclaves, granodiorites, and granites ages range from 183 to 189 Ma. They are characterized by enrichment in large-ion lithophile elements and depletion in high-field strength elements. The gabbros are classified as low-and medium-K tholeiitic, granodiorites and granites are high-K calc-alkaline I-type, and diorite enclaves are calc-alkaline transitional series. The gabbros have zircon [epsilon] Hf(t) values of 6.81-9.89, whole-rock [.sup.87]Sr/[.sup.86][Sr.sub.(i)] = 0.7043-0.7044, and [epsilon] Nd(t) from 2.72 to 2.80. The diorite enclaves have zircons with [epsilon] Hf(t) values of 8.26-12.80, whole-rock [.sup.87]Sr/[.sup.86][Sr.sub.(i)] = 0.7051, and [epsilon] Nd(t) from 0.96 to 1.09. The granodiorites and granites have zircon [epsilon] Hf(t) values of 7.59-12.87, whole-rock [.sup.87]Sr/[.sup.86][Sr.sub.(i)] = 0.7042-0.7066, and [epsilon]Nd(t) from 2.33 to 2.61. These data indicate that gabbroic magmas were derived from partial melting of a depleted mantle wedge metasomatized by subduction-related fluids. The basaltic magma underplated and heated the juvenile crust, whereas the granodiorites and granites might be the product of fractional crystallization of a mixture of basaltic and felsic magmas or derived from partial melting of the juvenile lower crust. Our data constrain the petrogenesis of these Early Jurassic intrusive rocks which are attributed to subduction of the Paleo-Pacific Plate beneath Eurasia continent in northeastern China. Key words: Early Jurassic, intrusive rocks, petrogenesis, Paleo-Pacific Plate subduction, Sr-Nd-Hf isotope, Yanbian area, 1. Introduction Understanding the generation and emplacement of granitic magmas is necessary to deduce the internal structure, formation, and evolution of continental crust (Pearce 1983; Barbarin 1999; Condie and Kroner [...]

In his paper 'Uber das Bewegungsbild von Faltengebirgen' [On the movement pattern of folded mountains], published in the almanac of the Austrian Geological Survey in Vienna, Otto Ampferer from Innsbruck (Austria) presented a series of geotectonic considerations and interpretations, which today are summarized under the term 'theory of undercurrent'. The interpretation of these processes occurring in the deep crust of the Earth and in the upper mantle was mainly kinematic. For a long time, the tectonic passivity of the magma being anorogenic was dogma until Ampferer's undercurrent theory changed this in 1906, according to which folds and thrusts on the Earth's surface portray motions of the deeper magmatic substratum. In these undercurrents, Ampferer recognized the crucial forces that lead to the formation of ocean basins and high mountains on the edges of the drifting continents. In his paper on the history of the formation of the Atlantic region, he presented already, in 1941, a process anticipating what is now known as seafloor spreading. Dans son article intitule <>, publie dans l'almanach de la Commission geologique d'Autriche a Vienne, Otto Ampferer, d'Innsbruck (Autriche), presentait une serie de considerations et d'interpretations geotectoniques que resume aujourd'hui le terme<>. L'interpretation de ces processus se produisant dans la croute profonde de la terre et dans le manteau superieur etait principalement cinematique. Longtemps, la passivite tectonique du magma comme etant anorogenique etait un dogme, jusqu'a l'avenement de la theorie des sous-courants d'Ampferer en 1906, selon laquelle les plis et chevauchements a la surface de la Terre refletent des mouvements du substrat magmatique plus profond. Dans ces sous-courants, Ampferer reconnaissait des forces cruciales menant a la formation de bassins oceaniques et de hautes montagnes aux bordures des continents en derive. Dans son article sur l'histoire de la formation de la region atlantique, il presentait deja, en 1941, un processus qui anticipait ce que nous designons aujourd'hui l'expansion des fonds oceaniques., Biography Otto Ampferer was born on 1 December 1875 in Hotting near Innsbruck (Tyrol, Austria). His father was a postman and he, as well as his wife, came from old [...]

A diverse suite of tholeiitic to alkaline basalt and gabbroic intrusions located in the Coldwell Complex on the northern margin of the Midcontinent Rift exhibit unusual trace element signatures that show enriched large ion lithophile elements and light rare earth elements with negative Nb and Zr anomalies. These features are not typical of magmas derived by partial melting within or above a rising mantle plume, as might be expected in an early Midcontinent Rift magmatic event. In this paper, we provide a detailed geochemical study of a 500 m thick sequence of metabasalt that represents the earliest stage of magmatism in the Coldwell Complex. We show that contamination or crystallization processes or subsequent metasomatism cannot explain the trace element variations. Instead, we propose partial melting in a metasomatized Subcontinental Lithospheric Mantle source to explain the decoupled behavior of large ion lithophile elements from light rare earth elements and heavy rare earth elements and rare earth elements from high field strength elements and the enriched Nd isotope signature of metabasalt. Similar features occur in unit 5b of the Mamainse Point Volcanic Group located at the northern margin of the Rift. An objective of this paper is to relate Two Duck Lake gabbro, host rock for low-sulfur, high precious metal sulfide mineralization at the Marathon deposit, to the metabasalt sequence. The excellent match of trace element abundances in Two Duck Lake gabbro to metabasalt unit 3 confirms an early Coldwell Complex age for metabasalt and a Subcontinental Lithospheric Mantle source for Cu--platinum group element mineralized gabbros. Une succession diversifiée de basaltes tholéiitiques à alcalins et d'intrusions gabbroïques située dans le complexe de Coldwell à la bordure nord du rift médio-continental présente des signatures d'éléments traces inhabituelles qui montrent un enrichissement en éléments lithophiles à grand rayon ionique et en terres rares légères avec des anomalies négatives de Nb et Zr. Ces caractéristiques ne sont pas typiques de magmas issus d'une fusion partielle au-dessus d'un panache mantellique ascendant ou à l'intérieur de celui-ci, à l'instar de ce qui serait attendu durant un épisode magmatique associé au début du rifting médio-continental. Nous présentons une étude géochimique détaillée d'une séquence de 500 m d'épaisseur de métabasaltes qui représente le tout début du magmatisme dans le complexe de Coldwell. Nous démontrons que des processus de contamination ou de cristallisation ou encore un métasomatisme subséquent ne peuvent expliquer les variations des éléments traces. Nous proposons plutôt que la fusion partielle dans une source dans le manteau lithosphérique subcontinental métasomatisé explique le découplage du comportement des éléments lithophiles à grand rayon ionique de celui des terres rares légères et des terres rares lourdes, et le découplage du comportement des terres rares de celui des éléments à forte liaison atomique, ainsi que la signature enrichie des isotopes de Nd des métabasaltes. Des caractéristiques semblables sont observées dans l'unité 5b du Groupe volcanique de Mamainse Point situé à la bordure nord du rift. Un des objectifs du présent article est de relier le gabbro de Two Duck Lake, la roche hôte de la minéralisation en sulfures riche en métaux précieux et pauvre en soufre au gisement Marathon, à la séquence de métabasaltes. L'excellente concordance des abondances d'éléments traces dans le gabbro de Two Duck Lake et dans l'unité 3 des métabasaltes confirme un âge du début de la formation du complexe de Coldwell pour les métabasaltes et une source dans le manteau lithosphérique subcontinental pour les gabbros minéralisés en Cu--élément du groupe platine. [Traduit par la Rédaction], Introduction The Coldwell Complex (CC) in Ontario, Canada (Fig. 1), provides not only a complete record of alkaline intrusive magmatism (Mitchell and Platt 1978, 1982; Mitchell et al. 1993) during [...]

An introduction is presented in which the editor discusses articles within the issue on topics including changes occurring on the Earth's surface across a spectrum of spatial and temporal scales, influence of climate change on the Earth's surface in northern and coastal regions, and features and landforms generated during decline and aftermath of continental glaciation.

Presents a reply to the comment given by I. Brookes to the article "Late Wisconsinan stratigraphy and chronology of southern St. George's Bay, Newfoundland: a re-appraisal," by Trevor Bell, David G.E. Liverman, Martin J. Batterson and Kevin Sheppard, which appeared in the 2001 issue of the 'Canadian Journal of Earth Sciences." Disagreements in field observations and interpretations; Discussion of a complex sedimentary sequences of interbedded diamicton, gravel and mud above the basal till; Discounting the significance of a date given to a diamicton at Highlands.

Subaerial rise of Earth's first continents took place 3.3-3.2 Ga years ago. This had significant influence on the ocean, atmosphere, and biosphere. Two important sedimentological consequences of continental emersion were (1) development of terrestrial (alluvial fan-fluvial-aeolian) depositional systems and (2) formation of shallow-marine sedimentary basins near the continental margin. Late Paleoarchean-Neoarchean terrestrial deposits, including development of an extensive paleosol around 3.2 Ga, and Meso-Neoarchean shallow-marine deposits have been reported from the Singhbhum Craton, eastern India from several localities. However, lateral and vertical changes in sedimentary facies associations and stratigraphic correlation between these terrestrial to shallow-marine sedimentary deposits have not yet been investigated. In this paper, we have reviewed the sedimentological characteristics of Late Paleoarchean to Neoarchean (3.2-2.8 Ga) stratigraphic successions of the Singhbhum Craton and have discussed sea level change and mode of stratigraphic sequence building. Our analysis shows that Singhbhum granitoid complex was emplaced around 3.3 Ga in an intracontinental setting, resulting in high continental freeboard conditions that triggered terrestrial (alluvial fan-braided fluvial) sedimentation (Dhosrapahar Formation). Continental sedimentation continued until ca. 3.0 Ga. In the eastern (Simlipal Group), western (Birtola Formation), and southwestern (the Mankarchua, Mahagiri, and Keonjhar formations) parts, shallow-marine sedimentation occurred after 3.0 Ga as a result of transgression. However, in the northern part (Dhanjori Formation), continental sedimentation prevailed throughout the Archean. These Late Paleoarchean to Neoarchean terrestrial and near-coastal successions of Singhbhum Craton should be the prime targets for intense geobiological research. Key words: Paleoarchean, Mesoarchean, sedimentation, continental emergence, Singhbhum Craton, India, 1. Introduction It has been proposed that significant increase of continental freeboard (elevation of continents from the mean sea level, Taylor and McLennan 1985) took place in the early Paleoproterozoic [...]

The Mesoproterozoic Husky Creek Formation is an interlayered redbed and basalt package that overlies a ca. 2.5 km thick, regionally extensive basaltic plateau linked to the 1.27 Ga Mackenzie Large Igneous Province. This succession provides an opportunity to study the interaction between contemporaneous fluvial sedimentation and flood basalt volcanism. The Husky Creek Formation is approximately 1900 m thick, consisting predominantly of fluvial channel and subordinate floodplain and eolian strata dominated by lithic detritus intercalated with basalt flows. U-Pb dating of detrital zircon grains collected from four stratigraphic levels in the Husky Creek Formation reveals two main age groupings: (1) a 1270 Ma peak attributed to the Mackenzie Large Igneous Province; and (2) Pre-1.6 Ga detrital zircon ages, which reflect sources from a broad region of northwestern Laurentia and are interpreted to be recycled from underlying sedimentary rocks of the Hornby Bay Basin. An upsection decrease in the proportion of ca. 1270 Ma zircon grains, coupled with increasing sandstone compositional maturity, reflects the expansion of the drainage basin during burial of a volcanic pile, with recycling becoming more dominant as the Husky Creek Formation accumulated. The Husky Creek Formation was deposited in the waning stages of the Mackenzie Igneous Event by west-flowing rivers into a geographically restricted basin above an extensive mafic volcanic plateau. This paper provides insight into fluvial basin development during the aftermath of one of Earth's largest igneous events. Key words: fluvial sedimentology, Mackenzie LIP, Husky Creek Formation, Mesoproterozoic, detrital zircon geochronology, Introduction Large igneous provinces (LIPs), and particularlycontinental flood basalts, have been a subject of substantial research targeting their relationship to mantle plumes and continental breakup (Ernst and Buchan 1997). While [...]

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.)

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.)

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.)

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.)

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.)

Rugosuchus nonganensis, a new genus and species of crocodyliform, is erected on the basis of its peculiar cranial features. This late Early Cretaceous species represents the second, and most complete, crocodyliform known from northeastern China. Its discovery is significant for our understanding of both the local vertebrate fauna and its stratigraphical correlations, and the paleobiogeography of the Crocodyliformes. The palatine contribution to the anterior border of the choana excludes the new form from the Eusuchia, and evidence from osteoderms (not detailed in the present paper) suggests that the new form appears to be phylogenetically closer to the Eusuchia than to the Goniopholididae. Therefore, comparisons are made primarily with those taxa which have a closer relationship to the former than the latter. The unsculpted, depressed, and lobe-like posterolateral process of the squamosal is further demonstrated to be ontogenetically variable and thus inappropriate for use as a character in phylogenetic analyses.Rugosuchus nonganensis, un nouveau genre et une nouvelle espèce de crocodyliforme, est défini à partir de ses caractéristiques crâniennes particulières. Cette espèce du Crétacé précoce représente le second, et le plus complet, crocodyliforme connu provenant du nord-est de la Chine. Sa découverte est importante pour notre compréhension de la faune vertébrée locale, de ses corrélations stratigraphiques et de la paléobiogéographie des Crocodyliformes. La contribution du palatin au bord antérieur de la choane exclut la nouvelle forme des Eusuchiens, alors que des évidences (non détaillées dans le présent article) provenant des ostéodermes suggèrent que la nouvelle forme soit phylogénétiquement plus près des Eusuchiens que des Goniopholididés. Les comparaisons sont donc faites surtout avec les taxons qui ont une relation plus proche aux premiers qu'aux derniers. Finalement, nous démontrons que le processus postéro-latéral du squamosal, non sculpté, déprimé et de type lobe varie de façon ontogénétique et qu'il est donc inapproprié pour servir de caractère dans les analyses phylogénétiques.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

The recent discovery of the early dromaeosaurid Sinornithosaurus millenii Xu et al. 1999 is especially important for our understanding of maniraptoran evolution, particularly of avian origins. This paper presents a thorough description of the skull of this species, revises the diagnosis based on cranial features, and discusses similarities to those of other dromaeosaurids and Archaeopteryx. Distinctive cranial characteristics of S. millenii include the presence of a deep excavation on the posteroventral margin of the premaxilla, a diastema between the premaxillary and maxillary teeth, a number of pits and ridges on the anterolateral surface of the antorbital fossa, long posterolateral process of the parietal that are sharply posteriorly directed, the column-like margin of the pterygoid process of the quadrate, the bifurcated posterior end of the dentary, and a distinctive groove posterior to the anterior carina on the lingual surface of the premaxillary tooth crowns. The present study on the skull of S. millenii provides new information on the poorly known cranial anatomy of dromaeosaurid dinosaurs, revealing that dromaeosaurids share more similarities with Archaeopteryx than previously thought. It also provides evidence suggesting that early dromaeosaurids are more bird-like than the later, more derived ones, thus contradicting claims that more bird-like dinosaurs appeared later in fossil record than the earliest birds.La découverte récente du dromæosauridé précoce Sinornithosaurus millenii Xu et al., 1999, est spécialement importante pour notre compréhension de l'évolution des rapaces, surtout ceux d'origine aviaire. Cet article présente une étude complète du crâne de cette espèce, révise le diagnostic crânien et discute de ses similitudes avec ceux d'autres dromæosauridés et d'Archaeopteryx. Les caractéristiques crâniennes distinctives de S. millenii comprennent la présence d'une excavation profonde sur la bordure postéroventrale du prémaxillaire, un diasthème entre les dents prémaxillaires et maxillaires, un certain nombre de creux et de bosses sur la surface antérolatérale de la fosse antorbitale et un long processus postérolatéral du pariétal qui sont nettement dirigés vers l'arrière, une bordure de style colonne du processus ptérygoïde de l'os carré, une extrémité postérieure bifurquée du dentaire et un sillon distinctif en arrière de la carène antérieure sur la surface médiale des couronnes des dents prémaxillaires. La présente étude sur le crâne de S. millenii fournit de nouvelles informations sur l'anatomie crânienne peu connue des dinosaures dromæosauridés, révélant que les dromæosauridés partagent plus de points en communs avec Archaeopteryx qu'on ne le croyait antérieurement. Cette étude fournit également des évidences voulant que les formes précoces des dromæosauridés ressemblent plus à des oiseaux que les formes plus tardives et plus dérivées, contredisant ainsi les allégations que des dinosaures ressemblant plus à des oiseaux sont apparus plus tard dans les gisements fossilifères que les oiseaux les plus précoces.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

Introduces a series of articles featured in the special issue of the "Canadian Journal of Earth Sciences." Discussion of articles on the final compendium of papers on the Alberta Basement Transect of Lithoprobe.

This paper quantifies rates of shoreline change and investigates the influence of surficial geology on shoreline dynamics between 1950 and 2018 on Pelly Island, located 10 km off the Mackenzie Delta. Long-term changes in shoreline position were calculated using imagery analysis and Analysing Moving Boundaries Using R (AMBUR). The influence of shoreline exposure to predominant storm direction and influence of surficial geology were examined for northwestern and southeastern zones. The average annual linear regression rate (LRR) rate during the 1950-2018 observation period was -3.8 m*[a.sup.-1]. The end point rate (EPR) was calculated for seven observation periods: 1950-1972, 1972-1985, 1985-2000, 2000-2018, 2000-2013, 2013-2018, and 1950-2018. A mean EPR of -5.5 [+ or -] 0.7 m*[a.sup.-1] was calculated for the 2000-2018 period, and a maximum retreat rate of 46.7 [+ or -] 2.1 m*[a.sup.-1] was recorded during the 2013-2018 observation period. By comparing the rate of change for sections of historical shorelines with differing surficial geology and exposure to storms, it was possible to draw conclusions on why Pelly Island continues to have the highest retreat rates in the Mackenzie-Beaufort region. Greater retreat rates were observed in lacustrine deposits (5.3 m*[a.sup.-1]) compared with moraine deposits (2.7 m*[a.sup.-1]). In addition, shoreline exposure to the predominant storm direction from the northwest was found to be a major influence on rates of shoreline change in all observation periods. Key words: imagery analysis, shoreline retreat, surficial geology, exposure to storms. Le présent article quantifie les taux de changement des berges et explore l'influence de la géologie de surface sur la dynamique des berges de 1950 à 2018 autour de l'île Pelly, située à 10 km au large du delta du fleuve Mackenzie. Les variations à long terme de l'emplacement des berges ont été calculées à l'aide de l'analyse d'images et du logiciel AMBUR (Analysing Moving Boundaries Using R). L'influence de l'exposition des berges à la direction dominante des tempêtes et l'influence de la géologie de surface ont été examinées pour les secteurs nord-ouest et sud-est. Le taux de recul linéaire (TRL) annuel moyen durant la période d'observation de 1950 à 2018 est de -3,8 m*[a.sup.-1]. Le taux entre points de fin (TPF) a été calculé pour sept périodes d'observation, à savoir : 1950-1972, 1972-1985, 1985-2000, 2000-2018, 2000-2013, 2013-2018 et 1950-2018. Un TRL moyen de -5.5 [+ or -] 0,7 m*[a.sup.-1] a été calculé pour la période de 2000-2018 et un taux de recul maximum de 46,7 [+ or -] 2,1 m*[a.sup.-1] a été enregistré durant la période d'observation de 2013-2018. En comparant le taux de changement pour des sections de berges passées présentant différentes geologies de surface et expositions aux tempêtes, il est possible de tirer des conclusions sur les raisons pour lesquelles l'île Pelly continue de présenter les taux de recul les plus élevés de la région de Mackenzie-Beaufort. Les taux de recul observés sont plus importants pour les dépôts lacustres (5,3 m*[a.sup.-1]) que pour les dépôts de moraine (2,7 m*[a.sup.-1]). En outre, l'exposition des berges à la direction dominante des tempêtes émanant du nord-ouest s'avère exercer une influence majeure sur les taux de changement des berges pour toutes les périodes d'observation. [Traduit par la Rédaction] Mots-clés : analyse d'image, recul de berges, géologie de surface, exposition aux tempêtes., Introduction During the 1950-2000 period, permafrost coastlines along the circum-Arctic were eroding at a mean rate of -0.5 m*[a.sup.-1] (Lantuit et al. 2012). Some of the highest reported rates of [...]

The Eocene to Miocene Cypress Hills Formation (CHF) spans 28 million years and forms the conglomeratic caprock of the Cypress Hills and Swift Current plateaus in southwestern Saskatchewan and southeastern Alberta. These stacked fluvial, floodplain, and lacustrine deposits preserve the only high latitude, non-polar mammalian fossil assemblage (Uintan to Hemingfordian land mammal stages) in Canada. The Quarry is the oldest CHF (Chadronian 1, late Eocene) site documented in the Cypress Hills region north of the town of Eastend. The Quarry was originally discovered in 1962, after bones were found to be eroding out of the base of a road cut north of the ghost town of South Fork on the southeastern flanks of the Cypress Hills. Numerous field campaigns have resulted in the collection of fossils from a multitaxonomic bonebed. This paper presents a detailed sedimentologic, paleontologic, and taphonomic study to establish a depositional environment framework of the Southfork Quarry. This site was deposited at the onset of the Eocene--Oligocene climate transition, a critical time of climate change during the Paleogene. Six facies and two facies associations are characterized for the Quarry, shifting from a braided-fluvial system to a debris flow-filled incised channel. Patterns of skeletal accumulations and bone surface modification indicate that the assemblage accumulated over a significant interval of time in different depositional environments. This study provides critical insight into environmental shifts driven by climate change and relates these findings to a broader understanding of the Eocene--Oligocene transition in North America. Key words: Paleogene, fluvial, Western Canada, Chadronian, Megacerops coloradensis La Formation éocène à miocène des collines du Cyprès couvre 28 millions d'années et forme la roche conglomératique recouvrant les plateaux des collines du Cyprès et de Swift Current dans le sud-ouest de la Saskatchewan et le sud-est de l'Alberta. Ces dépôts fluviaux, lacustres et de plaine inondable empilés préservent le seul assemblage fossile mammalien non polaire de haute latitude (étages mammaliens continentaux Uintien à Hemingfordien) au Canada. La carrière Southfork représente le site de la Formation des collines du Cyprès (Chadronien 1, ?‰ocène tardif) le plus ancien documenté dans la région des collines du Cyprès au nord du village d'Eastend. La carrière a été découverte en 1962, après la découverte d'ossements exposés par l'érosion à la base d'une tranchée de route au nord du village fantôme de South Fork, sur les flancs sud-est des collines du Cyprès. De nombreuses campagnes de terrain se sont traduites par la collecte de fossiles d'un lit à ossements multitaxonomique. L'article présente une étude sédimentologique, paléontologique et taphonomique détaillée visant à établir un cadre pour le milieu de dépôt de la carrière de Southfork. Ce site a été déposé au début de la transition climatique éocène-oligocène, une période de changement climatique clé durant le Paléogène. Six faciès et deux associations de faciès sont caractérisés pour la carrière, passant d'un réseau fluvial anastomosé à un chenal encaissé rempli par des coulées de débris. Les motifs d'accumulation de squelettes et de modification des surfaces des os indiquent que l'assemblage s'est accumulé durant un intervalle de temps important dans différents milieux de dépôt. L'étude fournit de nouveaux renseignements clés sur des changements environnementaux induits par des changements climatiques et relie ces constatations à une compréhension plus large de la transition de l'?‰ocène à l'Oligocène en Amérique du Nord. [Traduit par la Rédaction] Mots-clés : Paléogène, fluvial, Ouest canadien, Chadronien, Megacerops coloradensis, Introduction The Eocene toMiocene Cypress Hills Formation (CHF) spans 28 million years, forming the conglomeratic caprock of the Cypress Hills plateau in southwestern Saskatchewan and southeastern Alberta (Fig. 1). The [...]

The collaborative federal--provincial Southern Indian Lake project in north-central Manitoba covered an area of more than 3500 [km.sup.2] of the Trans-Hudson orogen. Regional-scale geological mapping, sampling, and lithogeochemical, isotopic, and geochronological studies resulted in the identification of distinct assemblages of supracrustal rocks and varied episodes of plutonism. A granodiorite gneiss dated at ca. 2520 Ma is interpreted to represent the basement of the Southern Indian domain and is considered a separate crustal domain, named the Partridge Breast block. The Churchill River assemblage is composed of juvenile pillow basalt with intervening clastic sedimentary rocks, possibly a reflection of plume magmatism related to initial rifting of the Hearne craton margin. The Pukatawakan Bay assemblage consists mainly of massive to pillowed, juvenile metabasaltic rocks and associated basinal metasedimentary rocks. The Partridge Breast Lake assemblage is dominated by continental-arc volcanic and volcaniclastic rocks associated with basinal metasedimentary rocks. The Strawberry Island assemblage, consisting of arenite and polymictic conglomerate, is interpreted to have been deposited in a foreland-basin basin or intra-orogen pull-apart basin environment. The Whyme Bay assemblage is characterized by fluvial-alluvial orogenic sediments and is temporally linked to the Sickle Group rocks in the Lynn Lake greenstone belt. Granitoid rocks, dominantly monzogranite and granodiorite, range in age from ca. 1890 to 1830 Ma and occur throughout the Southern Indian domain, and intermediate and mafic intrusions of similar ages are also present. In this paper, we integrate these new data into a tectonic framework for the Southern Indian domain of the Trans-Hudson orogen in Manitoba. Key words: tectonics, Trans-Husdon orogen, regional geology, Manitoba, Southern Indian domain, geochemistry, detrital geochronology. Resume : Le projet du lac Southern Indian, une collaboration federale--provinciale, dans le centre-nord du Manitoba, a couvert une superficie de plus de 3500 [km.sup.2] de l'orogene trans-hudsonien. La cartographie geologique, l'echantillonnage et des etudes lithogeochimiques, isotopiques et geochronologiques a l'echelle regionale ont mene a la delimitation de differents assemblages de roches supracrustales et episodes de plutonisme. Un gneiss granodioritique ayant donne un age d'environ 2520 Ma est interprete comme representant le socle du domaine de Southern Indian et constituant un domaine crustal distinct appele le bloc de Partridge Breast. L'assemblage du fleuve Churchill est compose de basaltes en coussins juveniles dans lesquels sont intercalees des roches sedimentaires clastiques, refletant possiblement un magmatisme de panache associe au rifting initial de la bordure du craton de Hearne. L'assemblage de la baie de Pukatawakan est principalement constitue de roches metabasaltiques juveniles massives a en coussins et de roches metasedimentaires de bassin associees. Dans l'assemblage du lac Partridge Breast, des roches volcaniques et volcanoclastiques d'arc continental associees a des roches metasedimentaires de bassin sont dominantes. L'assemblage de File Strawberry, constitue d'arenites et de conglomerate polymictiques, est interprete comme ayant ete depose dans un milieu de bassin d'avant-pays ou de bassin de transtension intraorogenique. L'assemblage de la baie de Whyme est caracterise par des sediments orogeniques fluviaux-alluviaux et est relie dans le temps aux roches du Groupe de Sickle dans la ceinture de roches vertes du lac Lynn. Des roches granitoides a predominance de monzogranite et granodiorite ont des ages allant d'environ 1890 a 1830 Ma et sont presentes partout dans le domaine de Southern Indian, et des intrusions intermediaires et mafiques d'ages semblables sont egalement presentes. Le present article integre ces nouvelles donnees dans un cadre tectonique pour le domaine de Southern Indian de l'orogene trans-hudsonien au Manitoba. [Traduit par la Redaction] Mots-cles: tectonique, orogene trans-hudsonien, geologie regionale, Manitoba, domaine de Southern Indian, geochimie, geochronologie de mineraux detritiques., Introduction The 'Trans-Hudson orogen' (THO) (Hoffman 1981; Lewry et al. 1981) is the belt of deformed and metamorphosed rocks that developed as a result of the Paleoproterozoic closure of the [...]

The Kamouraska Formation is a quartz-arenitic unit of latest Cambrian--earliest Ordovician age in the Quebec Appalachians that was deposited by hyperconcentrated to concentrated density flows in a meandering submarine canyon on the continental slope bordering the Iapetus Ocean, as outlined in a companion paper. Detailed petrographic study of the quartz arenites of the Kamouraska Formation combined with scanning electron microscopy of grain surface textures suggests that the quartz sands are of eolian origin having been derived from an inland desert or, less likely, a barrier beach dune system. Transport of the mature quartz-arenitic sand onto the shelf and deposition into the deep sea was not accompanied by substantial mixing with material from other sources thus preserving the inherited eolian characteristics. A modern analogue for the eolian interpretation of the deep-sea quartz-arenite beds is as follows: thick, Late Pleistocene eolian sand beds on a modern abyssal plain in the East Atlantic referred to as eolian-sand turbidites that were deposited in the deep sea during glacial sea level lowstands when eolian sand transport to canyon heads was enabled by an exposed and shortened shelf. Similarly, an established sea level lowstand at the Cambro-Ordovician boundary would have facilitated the introduction of eolian sand of the Kamouraska Foundation into canyon heads on the upper slope from where turbidity currents and related density flows were triggered. Correlation of the Kamouraska Formation with the quartz arenites of the Cairnside Formation of Quebec (Keeseville Formation in northern New York State, Nepean Formation in southern Ontario) links the deep-sea deposits with remnants of an inland dune system. La Formation de Kamouraska est constituee d'une unite d'arenite quartzique (Cambrien superieur--Ordovicien inferieur) dans les Appalaches du Quebec; elle a ete deposee par des courants de densite hyperconcentres a concentres dans un canyon sous-marin a meandres sur la pente continentale a la bordure de l'Ocean Iapetus, tel que souligne dans un article complementaire. Une etude petrographique detaillee des arenites quartziques de la Formation de Kamouraska jumelee a une microscopie electronique a balayage des textures de surface des grains suggerent que les sables quartzeux sont d'origine eolienne et qu'ils proviennent d'un desert d'arriere-pays ou, ce qui est moins probable, d'un systeme de dunes de cordon littoral. Le transport du sable arenite-quartz mature sur la plateforme continentale et sa deposition en mer profonde n'ont pas ete accompagnes d'un malaxage important avec du materiel d'autres sources, preservant ainsi les caracteristiques eoliennes heritees. Un analogue moderne pour l'interpretation eolienne des lits d'arenite quartzique de mer profonde est le suivant: d'epais lits de sables eoliens (Pleistocene tardif) sur une plaine abyssale moderne dans l'Atlantique Est, connus en tant que turbidites de sables eoliens, qui ont ete deposes en mer profonde durant les periodes de bas niveau de la mer en periode glaciaire lorsque le transport du sable eolien vers les tetes des canyons a ete aide par une plateforme exposee et raccourcie. De la meme maniere, une periode de bas niveau de la mer a la limite entre le Cambrien et l'Ordovicien aurait facilite l'introduction du sable eolien Kamouraska dans les tetes des canyons sur la pente superieure d'ou des courants de turbidite et des ecoulements de densite associes etaient declenches. Une correlation entre la Formation de Kamouraska et les arenites quartziques de la Formation Cairnside du Quebec (Formation Keeseville du Nord de l'Etat de New York, Formation Nepean de l'Ontario) relie les depots de mer profonde a des reliques d'un systeme de dunes d'arriere-pays. [Traduit par le Redaction], Introduction The Cambro-Ordovician Kamouraska Formation in the Quebec Appalachians has been interpreted in a companion paper by Malhame and Hesse (2011) as a deep-water clastic succession consisting of sedimentary gravity [...]

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.)

During many decades, the town of Moulay Yacoub underwent an important urban expansion to meet the high demand on housing fuelled by tourism activities, which constitute the backbone of the town's economy. Unfortunately, the majority of buildings, both private and public, suffer from varying levels of damage related to the lithological, climate, and geomorphic settings of the area. In fact, the town is built on a marly hill prone to various types of mass movements, ranging from shallow soil creep to large slides. In addition, vertical displacement related to swelling/shrinkage behaviour of these Miocene marls is widespread in the area. The present paper presents a multi-disciplinary approach to investigate the activity and the interaction between slow-moving urban landslides and expansive soils within the urban perimeter of Moulay Yacoub. In fact, the severe seasonal contrast characterised by intense rainfall over short periods constitutes the main triggering factor of the instability phenomena in the region. Moreover, the desiccation cracks affecting marly soils are indicators of their expansive behaviour, which is very obvious in geotechnical tests results. The other geotechnical parameters obtained from laboratory tests show that the shallow marl samples are severely weathered compared with those of the compact material extracted at greater depth. The borehole data and seismic noise survey allows the detection of several impedance contrasts corresponding to the weathered layer--bedrock boundary, which in some cases corresponds to the rupture surface of the inventoried landslides. The very slow but perennial activity of the later processes is well documented by the inclinometers, the PS-InSAR monitoring, and building damage assessment surveys. Indeed, this case study highlights the complementarity of techniques used in this multi-disciplinary approach that give a multi-faceted understanding of slope instability processes and should provide a blueprint for future site-specific studies in the region. Key words: urban landslide, expansive soils, multi-disciplinary analysis, building damage. Pendant de nombreuses décennies, la ville de Moulay Yacoub a connu une importante urbanisation en réponse à la forte demande de logements induite par l'activité touristique, qui constitue l'épine dorsale de l'économie de la ville. Mal-heureusement, la majorité des immeubles, tant privés que publics, ont subi des dommages d'intensité variable associés aux contexte lithologique, climatique et géomorphologique de la région. La ville est en effet construite sur une colline mar-neuse propice à différents types de mouvements de terrain allant du fluage de sols peu profonds à de grands glissements. En outre, des déplacements verticaux associés au comportement de gonflement et retrait de ces marnes miocènes sont répandus dans la région. L'article présente une approche multidisciplinaire à l'étude de l'activité et des interactions de glissements de terrain urbains de faible vélocité et de sols gonflants à l'intérieur du périmètre urbain de Moulay Yacoub. L'important contraste saisonnier caractérisé par des pluies intenses sur de courtes périodes est le principal élément déclen-cheur de phénomènes d'instabilité dans la région. En outre, des fissures de dessiccation en terrains marneux constituent des indicateurs du comportement gonflant de ces derniers, que les résultats d'essais géotechniques font clairement ressortir. Les autres paramètres géotechniques obtenus d'essais en laboratoire montrent une intense météorisation des échantillons de marnes peu profondes comparativement aux matériaux compacts à plus grande profondeur. Les données de forage et levés de bruit sismique font ressortir plusieurs contrastes d'impédance correspondant au contact de la couche météori-sée et du roc qui, dans certains cas, coïncide avec la surface de rupture des glissements de terrain recensés. L'activité très lente, mais soutenue des processus plus récents est bien documentée par les essais inclinométriques, la surveillance par PS-InSAR et les évaluations des dommages aux bâtiments. La présente étude de cas souligne notamment la complémentarité des techniques utilisées dans cette approche multidisciplinaire, qui permet une compréhension multifactorielle des processus d'instabilité des pentes et devrait constituer un modèle pour des études de site futures dans la région. [Traduit par la Rédaction] Mots-clés : glissement de terrain urbain, sols gonflants, analyse multidisciplinaire, dommages aux immeubles., Introduction Slope mass movements are among the most widespread geological hazards in the world (Schuster 1996; Schuster and Highland 2001). In urban extensions worldwide, the local construction and land use [...]

Infestation by the mountain pine beetle, Dendroctonus ponderosae, decimated the forests of central British Columbia from 1999 to 2012, severely impacting the forest industry of the Nechako-Chilcotin plateau. In response, all levels of government recognized the value in developing other areas of economic activity, such as hydrocarbon and mineral exploitation, to support local economies. Exploration for resources beneath the Nechako-Chilcotin plateau has historically been constrained by Tertiary volcanic sequences and Quaternary glacial deposits that obscure the underlying geology and limit geophysical imaging. Thus, a coordinated program comprising additional geological mapping, borehole data analysis, and modern geophysical surveys of the area was initiated in 2006, with the objective of better defining the subsurface geology, solving problems of imaging through the complex near-surface, and developing improved regional geological and tectonic models. An initial set of papers arising from this fieldwork, which focused on issues relevant to mineral and hydrocarbon exploration, was published in June 2011 in a Special Issue of the Canadian Journal of Earth Sciences. This Introduction to the second 'Mountain Pine Beetle' Special Issue summarizes a set of scientific papers that focus on topics more related to hydrocarbon exploration and the large-scale structure of the crust. The papers deal with the development, thickness, and present distribution of the most prospective Cretaceous sedimentary rocks, as well as characterizing the physical properties of the near-surface volcanic units. De 1999 a 2012, une infestation par le dendroctone du pin ponderosa, Dendroctonus ponderosae, a decime les forets du centre de la Colombie-Britannique et a severement nui a l'industrie forestiere du plateau Nechako-Chilcotin. Tous les niveaux de gouvernement ont reagi et reconnu l'importance de developper d'autres secteurs d'activite economique, par exemple l'exploration petroliere et minerale, pour soutenir l'economie locale. L'exploration pour les ressources sous le plateau Nechako-Chilcotin a historiquement ete entravee par les suites de roches volcaniques du Tertiaire et les depots glaciaires du Quaternaire; ces suites masquent la geologie sous-jacente et limitent l'imagerie geophysique. Ainsi, en 2006, un programme coordonne comprenant de la cartographie geologique additionnelle, l'analyse de donnees de forages et des leves geophysiques modernes a ete entrepris dans le secteur afin de mieux definir la geologie sous la surface, resoudre les problemes d'imagerie complexe a proximite de la surface et developper de meilleurs modeles geologiques et tectoniques regionaux. Un premier ensemble d'articles decoulant de ce travail de terrain, qui ciblait l'exploration petroliere et minerale, a ete publie en juin 2011 dans un numero special de la Revue canadienne des sciences de la Terre. La presente introduction au deuxieme numero special sur le dendroctone du pin ponderosa resume un ensemble d'articles scientifiques portant sur des sujets relies a l'exploration pour les hydrocarbures et la structure de la croute a grande echelle. Les articles traitent du developpement, de l'epaisseur et de la distribution actuelle des roches sedimentaires cretacees les plus prometteuses, ainsi que sur la caracterisation des proprietes physiques des unites volcaniques pres de la surface. [Traduit par la Redaction], The Nechako-Chilcotin plateau lies at the heart of the interior region of British Columbia affected by the mountain pain beetle infestation (Fig. 1), which began in 1999 and by 2012 [...]

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.)

The Hare Indian Formation (HIF) is a late Eifelian to Givetian organic-rich mudstone constituting the lower portion of the Horn River Group (HRG), which has been minimally scrutinized in the literature. This paper proposes depositional environments and a sequence stratigraphic framework for the HIF. Using composition data collected via energy-dispersive X-ray fluorescence, geochemical proxies inform detrital input, silica source, and paleoredox conditions. Cross-plots and chemostratigraphic profiles of detritally sourced Al, Ti, and K and redox-sensitive Mo and V inform depositional and stratigraphic constraints. Silica proportions vary, indicating that sediment was derived from detrital and biogenic sources. Al, Ti, and K distributions increase upwards, showing increased continentally sourced minerals. Redox-sensitive metals are highest in the Bluefish Member (BM), suggesting intermittent euxinia. Based on the presence of continental and pelagic sediments, the sedimentary environment is interpreted as proximal- to mid-shelf. These proxies guide systems tract interpretations. Si and redox-sensitive metal concentrations peak higher in the BM, accompanied by lowered concentrations of Al, Ti, and K, suggesting a maximum flooding surface. At the top of the Prohibition and Bell Creek members, redox-sensitive enrichments are lower with higher concentrations of Al, Ti, and K, suggesting a maximum regressive surface. Transgression occurred during the initial deposition of the BM, followed by regression for the remainder of the HIF. The sedimentology of the HIF can be difficult to decipher; the use of chemostratigraphy supports its geological history (including sedimentation trends and a local record of relative sea level) using methods that may be applied to other finegrained successions. Key words: chemostratigraphy, Hare Indian Formation, Horn River Group, Devonian, Givetian, mudstone, fine-grained, sequence stratigraphy, geochemistry, Northwest Territories, Central Mackenzie Valley, Mackenzie Mountains, XRF, X-ray fluorescence. La Formation de Hare Indian (FHI) est un mudstone tardi-eifelien a givetien riche en matiere organique constituant la partie inferieure du Groupe de Horn River (GHR), qui a fait l'objet de peu d' etudes publiees. Le present article propose des milieux de depot et un cadre de stratigraphie sequentielle pour la FHI. A la lumiere de donnees de composition obtenues par fluorescence X a dispersion d' energie, des variables substitutives geochimiques apportent des precisions sur les apports detritiques, les sources de silice et les conditions d'oxydoreduction passees. Des graphiques de correlation et des profils chimiostratigraphiques de l'Al, du Ti et du K de source detritique et du Mo et du V, qui sont sensibles aux conditions d'oxydoreduction, mettent en lumiere des contraintes stratigraphiques et de sedimentation. Les proportions de silice varient, indiquant que les sediments proviennent de sources detritiques et biogenes. Les concentrations d'Al, de Ti et de K augmentent vers le haut, indiquant une augmentation de mineraux de source continentale. Les proportions des metaux sensibles a l'oxydoreduction sont les plus grandes dans le membre de Bluefish (MB), laissant croire a un euxinisme intermittent. Etant donne la presence de sediments continentaux et pelagiques, un milieu sedimentaire de plateforme proximale a mediale est interprete. Ces variables substitutives guident l'interpretation des corteges de depot. Les concentrations de Si et de metaux sensibles a l'oxydoreduction atteignent un maximum plus haut dans le MB, accompagne de concentrations moindres d'Al, de Ti et de K, ce qui indiquerait une surface d'inondation maximum. Au sommet des membres de Prohibition et de Bell Creek, les enrichissements de metaux sensibles a l'oxydoreduction sont plus faibles et les concentrations d'Al, de Ti et de K, plus grandes, ce qui indiquerait une surface de regression maximum. Une transgression s'est produite durant le depot initial du MB, suivie d'une regression pour le reste de la FHI. La sedimentologie de la FHI peut etre difficile a etablir; l'utilisation de la chimiostratigraphie appuie son histoire geologique (y compris les tendances de sedimentation et un registre local du niveau relatif de la mer) en faisant appel a des methodes qui pourraient etre appliquees a d'autres successions a grains fins. [Traduit par la Redaction] Mots-cles : chimiostratigraphie, Formation de Hare Indian, Groupe de Horn River, Devonien, Givetien, mudstone, a grains fins, stratigraphie sequentielle, geochimie, Territoires du Nord-Ouest, vallee centrale du fleuve Mackenzie, monts Mackenzie, fluorescence X., Introduction Unconventional reservoirs have become increasingly prevalent in the energy industry and, as such, organic-rich mudstones have become common targets of exploration and production in basins across North America. This [...]

Totolapa is one of the amber Lagerstatten from Chiapas, southwestern Mexico, which include the Simojovel and Huitiupan deposits. Despite the remarkable paleobiological heritage of Chiapas amber biota, the fossil record of ants from Totolapa has so far not been well studied. Based on exceptionally preserved specimens, four ant genera from the Totolapa amber deposits are reported in this paper, including Forelius, Azteca, Tapinoma, and Camponotus (Hymenoptera, Formicidae). Whereas the genera Azteca, Tapinoma, and Camponotus are previously known from amber quarries of Simojovel, this paper represents the first record of the presence of Forelius in Chiapas amber. Resume: Totolapa constitue un des Lagerstatten de l'ambre du Chiapas, au sud-ouest du Mexique, ou se trouvent aussi les depots de Simojovel et Huitiupan. En depit de l'etonnant patrimoine paleobiologique des biotes contenus dans l'ambre chiapaneque, les fossiles de fourmis de Totolapa ont ete peu etudies jusqu'a present. A partir de l'etude de specimens exceptionnellement preserves des depots d'ambre du Totolapa, cet article presente quatre genres de fourmis: Forelius, Azteca, Tapinoma, et Camponotus (Hymenoptera, Formicidae). Alors que les genres Azteca, Tapinoma et Camponotus ont deja ete inventoriees dans les carrieres d'ambre de Simojovel, la presence de Forelius est inedite concernant l'ambre du Chiapas., Introduction Totolapa is an outstanding Chiapas amber deposit that may be considered a Konservat-Lagerstatte on the basis of its exceptional fossil preservation. Plants and animals trapped within fossil resin show [...]

For sheer complexity, braincases are generally considered anatomically conservative. However, recent research on the braincases of tyrannosaurids have revealed extensive morphological variations. This line of inquiry has its root in Dale Russell's review of tyrannosaurids in which he established Daspletosaurus torosus--a large tyrannosaurine from the Campanian of southern Alberta. In the wake of systematic revisions to tyrannosaurines previously assigned to Daspletosaurus, one potentially distinct species remains undescribed. This paper describes and compares a braincase referable to this species with that of the holotype for Daspletosaurus torosus using computerized-tomography-based reconstructions. The two braincases have numerous differences externally and internally. The specimen of Daspletosaurus sp. has a bottlenecked olfactory tract, short and vertical lagena, and a developed ascending column of the anterior tympanic recess. The holotype of Daspletosaurus torosus has many unusual traits, including an anteriorly positioned trochlear root, elongate common carotid canal, distinct chamber of the basisphenoid recess, asymmetry in the internal basipterygoid aperture, and laterally reduced but medially expanded subcondylar recess. This comparison also identified characters that potentially unite the two species of Daspletosaurus, including deep midbrain flexures in the endocasts. However, many character variations in the braincases are known in other tyrannosaurids to correlate with body size and maturity, or represent individual variations. Therefore, taxonomic and phylogenetic signals can be isolated from background variations in a more comprehensive approach by using additional specimens. New information on the two braincases of Daspletosaurus is consistent with the emerging view of tyrannosaurid braincases as highly variable, ontogenetically dynamic character complexes. Key words: endocast, inner ear, pneumaticity, Late Cretaceous, Campanian, Alberta, Laramidia. Du seul point de vue de la complexite, l'anatomie des boites craniennes est generalement consideree comme etant conservative. Des recherches recentes sur les boites craniennes de tyrannosaurides ont toutefois revele une grande variabilite morpho-logique. Cette avenue d'etude prend sa source dans la synthese sur les tyrannosaurides de Dale Russell, dans laquelle l'auteur etablit Daspletosaurus torosus, un grand tyrannosaurine du Campanien du sud de l'Alberta. A la suite de revisions systematiques de tyrannosaurines precedemment affectes a Daspletosaurus, une espece potentiellement distincte demeure non decrite. Le present article decrit une boite cranienne pouvant etre referee a cette espece et la compare a celle de l'holotype de Daspletosaurus torosus en utilisant des reconstitutions basees sur la tomographie par ordinateur. De nombreuses differences tant externes qu'internes existent entre les deux boites craniennes. Le specimen de Daspletosaurus sp. presente des voies olfactives en goulot d'etranglement, une lagena courte et verticale, ainsi qu'une colonne ascendante developpee du recessus tympanique anterieur. L'holotype de Daspletosaurus torosus presente de nombreux caracteres inhabituels, dont une racine trochleaire positionnee anterieurement, un canal carotidien commun allonge, une cavite distincte du recessus basispheno'ide, une asymetrie de l'ouverture basip-terygo'ide interne et un recessus subcondylaire reduit lateralement, mais agrandi medialement. Cette comparaison fait egalement ressortir des caracteres qui pourraient unir les deux especes de Daspletosaurus, dont de profondes flexures mesen-cephales dans les endocastes. Il est toutefois etabli que de nombreuses variations de caracteres dans les boites craniennes chez d'autres tyrannosaurides sont correlees a la taille du corps et a la maturite ou representent des variations individuelles. Des signaux taxonomiques et phylogenetiques peuvent done etre isoles des variations de fond par une approche plus exhaustive en faisant appel a d'autres specimens. Les nouveaux renseignements sur les deux boites craniennes de Daspletosaurus concordent avec l'opinion emergente selon laquelle les boites craniennes de tyrannosaurides constituent des complexes de caracteres tres variables et dynamiques sur le plan ontogenique. [Traduit par la Redaction] Mots-cles: endocaste, oreille interne, pneumaticite, Cretace tardif, Campanien, Alberta, Laramidie., Introduction The description of Daspletosaurus torosus Russell, 1970 ushered in the modern era of research on North American tyrannosaur-ids. To Dale A. Russell, erecting Daspletosaurus was not a simple taxonomic [...]