A new type section for the Upper Triassic Siphon Member, Charlie Lake Formation, in northeast British Columbia

The highly deformed section at Open Bay is one of the few good exposures of a thick sedimentary unit within the prebatholithic rocks along coastal British Columbia. It provides new structural information relating to emplacement of a part of the Coast Range batholith and it contains an important Upper Triassic fauna unusually well represented. Structural and paleontological analyses are mutually supporting and are purposely combined in one paper.Thirteen ammonite genera from 14 localities clearly substantiate McLearn's tentative assignment to the Tropites subbullatus zone (Upper Karnian) and suggest a restriction to the T. dilleri subzone as defined in northern California.Contrary to an earlier view, the beds are lithologically similar across the whole bay except for variations in the intensity of deformation and thermal alteration. Their contact with slightly older relatively undeformed flows is apparently a zone of dislocation. Stratigraphic thicknesses cannot be measured with confidence, and subdivision into "Marble Bay Formation" and "Open Bay Group" cannot be accepted. Open Bay Formation is redefined to include all the folded marble and interbedded pillow lava at Open Bay. Lithologic and biostratigraphic correlation is suggested with the lower middle part of the Quatsino Formation on Iron River, 24 miles to the southwest. Basalt flows and pillowed volcanics west of Open Bay are correlated with the Texada Formation within the Karmutsen Group.The predominant folding is shown to precede, accompany, and follow intrusion of numerous andesitic pods and to precede emplacement of quartz diorite of the batholith. Structural asymmetry is shown to have originated through gentle cross-folding and emplacement of minor intrusives during deformation.

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A taxonomic and biostratigraphic re-evaluation of the Post Quarry vertebrate assemblage from the Cooper Canyon Formation (Dockum Group, Upper Triassic) of southern Garza County, western Texas

Earth and Environmental Science Transactions of the Royal Society of Edinburgh ◽

10.1017/s1755691013000376 ◽

2012 ◽

Vol 103 (3-4) ◽

pp. 339-364 ◽

Cited By ~ 14

Author(s):

Jeffrey W. Martz ◽

Bill Mueller ◽

Sterling J. Nesbitt ◽

Michelle R. Stocker ◽

William G. Parker ◽

...

Keyword(s):

Upper Triassic ◽

Type Section ◽

Stratigraphic Subdivision ◽

Vertebrate Assemblage

ABSTRACTThe Post Quarry, within the lower part of the type section of the Upper Triassic Cooper Canyon Formation in southern Garza County, western Texas, contains a remarkably diverse vertebrate assemblage. The Post Quarry has produced: the small temnospondylRileymillerus cosgriffi; the metoposauridApachesaurus gregorii; possible dicynodonts and eucynodonts; a clevosaurid sphenodontian; non-archosauriform archosauromorphs (Trilophosaurus dornorum, simiosaurians, and possiblyMalerisaurus); the phytosaurLeptosuchus; several aetosaurs (Calyptosuchus wellesi,Typothorax coccinarum,Paratypothorax, andDesmatosuchus smalli); the poposauroidShuvosaurus inexpectatus(“Chatterjeea elegans”); the rauisuchidPostosuchus kirkpatricki; an early crocodylomorph; several dinosauromorphs (the lagerpetidDromomeron gregorii, the silesauridTechnosaurus smalli, a herrerasaurid, and an early neotheropod); and several enigmatic small diapsids. Revised lithostratigraphic correlations of the lower Cooper Canyon Formation with the Tecovas Formation, the occurrence ofLeptosuchus, and the overall composition of the assemblage indicate that the Post Quarry falls within the Adamanian biozone, and not the Revueltian biozone. Stratigraphic subdivision of the Adamanian biozone may be possible, and the Post Quarry may be correlative with the upper part of the Adamanian biozone in Arizona. The age of the Post Quarry assemblage is possibly late Lacian or earliest Alaunian (late early Norian or earliest middle Norian), between 220 and 215 Ma.

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Paleomagnetism of the Triassic Nikolai Greenstone, McCarthy Quadrangle, Alaska

Canadian Journal of Earth Sciences ◽

10.1139/e77-223 ◽

1977 ◽

Vol 14 (11) ◽

pp. 2578-2592 ◽

Cited By ~ 96

Author(s):

J. W. Hillhouse

Keyword(s):

British Columbia ◽

High Temperature ◽

North America ◽

Vertical Axis ◽

Upper Triassic ◽

Present Position ◽

Stable Component ◽

South Central ◽

Early Mesozoic ◽

Lamellar Texture

Paleomagnetic evidence indicates that the extensive early Mesozoic basalt field near McCarthy, south-central Alaska, originated far south of its present position relative to North America. Results obtained from the Middle and (or) Upper Triassic Nikolai Greenstone suggest that those basalts originated within 15° of the paleoequator. This position is at least 27° (3000 km) south of the Upper Triassic latitude predicted for McCarthy on the basis of paleomagnetic data from continental North America. The Nikolai pole, as determined from 50 flows sampled at 5 sites, is at 2.2° N, 146.1° E (α95 = 4.8°). The polarity of the pole is ambiguous, because the corresponding magnetic direction has a low inclination and a westerly declination. Therefore, the Nikolai may have originated near 15° N latitude or, alternatively, as far south as 15° S latitude. In addition to being displaced northward, the Nikolai block has been rotated roughly 90° about the vertical axis. A measure of the reliability of this pole is provided by favorable results from the following tests: (1) Within one stratigraphic section, normal and reversed directions from consecutive flows are antipolar. (2) Consistent directions were obtained from sites 30 km apart. (3) Application of the fold test indicated the magnetization was acquired before the rocks were folded. (4) The magnetizations of several pilot specimens are thermally stable up to 550 °C. The stable component is probably carried by magnetite with lamellar texture, a primary feature commonly acquired by a basalt at high temperature during initial cooling of the magma. Geologic and paleomagnetic evidence indicates that the Nikolai is allochthonous to Alaska and that, together with associated formations in southern Alaska and British Columbia, it is part of a now disrupted equatorial terrane.

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Microbial framework in Upper Triassic (Carnian) patch reefs from Williston Lake, British Columbia, Canada

Palaeogeography Palaeoclimatology Palaeoecology ◽

10.1016/j.palaeo.2010.09.009 ◽

2010 ◽

Vol 297 (3-4) ◽

pp. 609-620 ◽

Cited By ~ 16

Author(s):

Rowan C. Martindale ◽

John-Paul Zonneveld ◽

David J. Bottjer

Keyword(s):

British Columbia ◽

Upper Triassic ◽

Patch Reefs

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Origin of the Tulameen ultramafic-gabbro complex, southern British Columbia

Canadian Journal of Earth Sciences ◽

10.1139/e69-040 ◽

1969 ◽

Vol 6 (3) ◽

pp. 399-425 ◽

Cited By ~ 28

Author(s):

D. C. Findlay

Keyword(s):

British Columbia ◽

Internal Structure ◽

Fractional Crystallization ◽

Volcanic Rocks ◽

Age Determination ◽

Upper Triassic ◽

Ultramafic Rocks ◽

Metasedimentary Rocks ◽

Gabbroic Intrusion

The Tulameen Complex is a composite ultramafic-gabbroic intrusion that outcrops over 22 sq. mi. (57 km2) in the Southern Cordillera of British Columbia. The complex intruded Upper Triassic metavolcanic and metasedimentary rocks of the Nicola Group, and on the basis of geologic relations and a K–Ar age determination (186 m.y.) is tentatively dated as Late Triassic.The principal ultramafic units — dunite, olivine clinopyroxenite, and hornblende clinopyroxenite — form an elongate, non-stratiform body whose irregular internal structure is best explained by deformation contemporaneous with crystallization of the rocks. The derivation of the ultramafic rocks is attributed to fractional crystallization of an ultrabasic magma. The gabbroic mass, which consists of syenogabbro and syenodiorite, partly borders and partly overlies the ultramafic body and was apparently intruded by it.The ultramafic and gabbroic parts of the complex probably formed from separate intrusions of different magmas, but the two suites have sufficient mineralogical and chemical features in common to indicate an ultimate petrogenic affinity of the magmas. Comparison of the Tulameen rocks with nearby intrusions of the same general age, in particular the Copper Mountain stock, suggests that they are members of a regional suite of alkalic intrusions. The possibility is also raised that these intrusions may be comagmatic with the Nicola volcanic rocks.

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An ichthyosaur forefin from the Triassic of British Columbia exemplifying Jurassic features

Canadian Journal of Earth Sciences ◽

10.1139/e91-139 ◽

1991 ◽

Vol 28 (10) ◽

pp. 1553-1560 ◽

Cited By ~ 16

Author(s):

C. McGowan

Keyword(s):

British Columbia ◽

North America ◽

Lower Jurassic ◽

Upper Triassic ◽

New Material ◽

Important Site

New ichthyosaur material is reported from an Upper Triassic locality on Williston Lake, northeastern British Columbia. The paucity of ichthyosaurs from the Triassic of North America make this a potentially important site. An isolated forefin is described, which is unlike that of any Triassic species from North America but which compares closely with certain Lower Jurassic species from England and Germany. The new material suggests that the transition in the ichthyosaurian fauna at the close of the Triassic may have been less abrupt than was previously supposed.

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