Oxide minerals in the Turnagain ultramafic complex, northwestern British Columbia

1978 ◽  
Vol 15 (12) ◽  
pp. 1893-1903 ◽  
Author(s):  
Thomas Clark
Keyword(s):  
British Columbia ◽  
Oxygen Fugacity ◽  
Upper Triassic ◽  
Turbidity Currents ◽  
Chrome Spinel ◽  
Magmatic Differentiation ◽  
Cooling Process ◽  
Ultramafic Complex ◽  
Wide Range ◽  
Oxide Minerals

The oxide minerals in the Turnagain ultramafic complex, an Alaskan-type intrusion of possible Upper Triassic age in northwestern British Columbia, offer some important clues concerning the composition of magmas from which they separated and the chemical changes that they underwent during the cooling process. Chromite occurs as disseminations and vein-like concentrations in dunite, and as disseminations in wehrlite and olivine clinopyroxenite. Ilmenite is found in hornblendite. A small amount of primary magnetite is associated with intercumulus sulfide. Chrome spinel exhibits a very wide range of compositions. The ratio 100 Mg/(Mg + Fe2+) ranges from 69.7–3.6, and this is paralleled by a decrease in Cr2O3 (60.1–9.3%), and by increases in Fe2O3, TiO2, and MnO. Chromite rims are poorer in Cr and richer in Fe3+ than chromite cores. Magmatic differentiation was responsible for most of these variations. Subsolidus re-equilibration caused Mg/Fe2+ zoning in coexisting chromite and olivine, the ratio decreasing in chromite rims and increasing in rims of contacting olivine grains. Subsolidus re-equilibration was probably responsible for the enrichment in Mg of the minerals in a chromite-rich layer relative to those in the adjacent dunite. Disseminated chromite originated by cotectic crystallization; chromite-rich layers may have been deposited by magmatic turbidity currents. Several mineralogical and chemical features suggest that oxygen fugacity in the magmas was relatively low.

STRUCTURE, STRATIGRAPHY, AND PALEONTOLOGY OF AN UPPER TRIASSIC SECTION ON THE WEST COAST OF BRITISH COLUMBIA

1965 ◽  
Vol 2 (5) ◽  
pp. 442-484 ◽  
Author(s):  
Donald Carlisle ◽  
Takeo Susuki
Keyword(s):  
British Columbia ◽  
Structural Information ◽  
Pillow Lava ◽  
Middle Part ◽  
Upper Triassic ◽  
Coast Range ◽  
Thermal Alteration ◽  
The West ◽  
Coastal British Columbia ◽  
Sedimentary Unit

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.

Mineral ages and zircon Hf isotopic composition of the Andong ultramafic complex: implications for the evolution of Mesozoic subduction system and subcontinental lithospheric mantle beneath SE Korea

2013 ◽  
Vol 151 (5) ◽  
pp. 765-776 ◽  
Author(s):  
GI YOUNG JEONG ◽  
CHANG-SIK CHEONG ◽  
KEEWOOK YI ◽  
JEONGMIN KIM ◽  
NAMHOON KIM ◽  
...  
Keyword(s):  
Lithospheric Mantle ◽  
Tectonic Setting ◽  
Eastern China ◽  
Mantle Xenoliths ◽  
Late Triassic ◽  
Magmatic Differentiation ◽  
Suprasubduction Zone ◽  
Ultramafic Complex ◽  
Yeongnam Massif ◽  
Subduction System

AbstractThe Phanerozoic subduction system of the Korean peninsula is considered to have been activated by at least Middle Permian time. The geochemically arc-like Andong ultramafic complex (AUC) occurring along the border between the Precambrian Yeongnam massif and the Cretaceous Gyeongsang back-arc basin provides a rare opportunity for direct study of the pre-Cretaceous mantle wedge lying above the subduction zone. The tightly constrained SHRIMP U–Pb age of zircons extracted from orthopyroxenite specimens (222.1±1.0 Ma) is indistinguishable from the Ar/Ar age of coexisting phlogopite (220±6 Ma). These ages represent the timing of suprasubduction zone magmatism likely in response to the sinking of cold and dense oceanic lithosphere and the resultant extensional strain regime in a nascent arc environment. The nearly coeval occurrence of a syenite-gabbro-monzonite suite in the SW Yeongnam massif also suggests an extensional tectonic setting along the continental margin side during Late Triassic time. The relatively enriched ɛHf range of dated zircons (+6.2 to −0.6 at 222 Ma) is in contrast to previously reported primitive Sr–Nd–Hf isotopic features of Cenozoic mantle xenoliths from Korea and eastern China. This enrichment is not ascribed to contamination by the hypothetical Palaeozoic crust beneath SE Korea, but is instead attributable to metasomatism of the lithospheric mantle during the earlier subduction of the palaeo-Pacific plate. Most AUC zircons show a restricted core-to-rim spread of ɛHf values, but some grains testify to the operation of open-system processes during magmatic differentiation.

Paleomagnetism of the Triassic Nikolai Greenstone, McCarthy Quadrangle, Alaska

1977 ◽  
Vol 14 (11) ◽  
pp. 2578-2592 ◽  
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.

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

2010 ◽  
Vol 297 (3-4) ◽  
pp. 609-620 ◽  
Author(s):  
Rowan C. Martindale ◽  
John-Paul Zonneveld ◽  
David J. Bottjer
Keyword(s):  
British Columbia ◽  
Upper Triassic ◽  
Patch Reefs

scholarly journals Intimate Stories: Aboriginal Women’s Lived Experiences of Health Services in Northern British Columbia and the Potential of Creative Arts to Raise Awareness About HPV, Cervical Cancer, and Screening

2013 ◽  
Vol 8 (1) ◽  
pp. 18 ◽  
Author(s):  
Virginia L. Russell ◽  
Sarah De Leeuw
Keyword(s):  
Cervical Cancer ◽  
British Columbia ◽  
Cancer Screening ◽  
Cervical Cancer Screening ◽  
Health Care Services ◽  
Formal Education ◽  
Cervical Screening ◽  
Sexual Health Care ◽  
Wide Range ◽  
Screening Services

Guided by feminist and community-based participatory methodologies and by efforts to decolonize health research practices, and undertaken with qualitative research methods (interviews, open-ended questionnaires, and analysis of arts-based expressions like storytelling, journaling, and picture-making), this research identified challenges and barriers that (predominantly Aboriginal) women in northern British Columbia faced when trying to access sexual health care services related to HPV and cervical cancer screening. The research also examined the possible effectiveness of creative or arts-based strategies to promote cervical health and screening awareness among young and/or traditionally underserved or marginalized women. We review findings from data gathered over six months during multiple interactions with 22 women from a wide range of ethnic backgrounds. Results confirm that ethnicity, finances, and formal education are determinants in women’s awareness about, access to, and use of cervical screening services, and that experiences of gendered victimization, feelings of disempowerment, and life circumstances all influenced women’s comfort levels with, access to, and use of cervical cancer screening services.

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

1969 ◽  
Vol 6 (3) ◽  
pp. 399-425 ◽  
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.

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

1991 ◽  
Vol 28 (10) ◽  
pp. 1553-1560 ◽  
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.

A population-viability-based risk assessment of Marbled Murrelet nesting habitat policy in British Columbia

2006 ◽  
Vol 36 (12) ◽  
pp. 3075-3086 ◽  
Author(s):  
J Douglas Steventon ◽  
Glenn D Sutherland ◽  
Peter Arcese
Keyword(s):  
British Columbia ◽  
Simulation Modelling ◽  
Population Viability ◽  
Nesting Habitat ◽  
Persistence Probability ◽  
Marbled Murrelet ◽  
The Pacific ◽  
Independent Population ◽  
Wide Range ◽  
Nesting Density

The Marbled Murrelet (Brachyramphus marmoratus Gmelin) is a small threatened seabird of the Pacific coast of North America. Through simulation modelling we varied the long-term minimum amounts and quality (nesting density) of old-forest nesting habitat to examine effects on murrelet population viability, our measure of population resilience. Applying diffusion approximations we estimated population longevity and persistence probability under uncertainties of at-sea demography and onshore edge effects affecting nesting success, time scale, spatial scale, and subpopulation structure. We cast our analysis in a Bayesian belief and decision network framework. We also applied the framework to spatially explicit land-use and murrelet inventory data for the northern mainland region of the British Columbia coast. We found a diminishing expected value of persistence probability (EVP), for a single independent population, below a nesting capacity of ≈5000 nesting pairs (≈15 000 birds), accelerating below 2000 pairs. A strategy of multiple semi-independent subpopulations provided a higher joint EVP across a wide range of total nesting capacity. There was little improvement in EVP, for any number of subpopulations, above 10 000 – 12 000 pairs (≈36 000 birds, 45%–60% of coastwide population estimate in 2001). Depending on estimates of nesting density, 12 000 pairs would require between 0.6 and 1.2 million ha of potential old-forest nesting habitat.

scholarly journals A coelacanth scale from the Upper Triassic Pardonet Formation, British Columbia, Canada

2004 ◽  
Vol 8 (4) ◽  
pp. 337-340 ◽  
Author(s):  
Yoshitaka Yabumoto ◽  
Andrew Neuman
Keyword(s):  
British Columbia ◽  
Upper Triassic
Sign in / Sign up

Export Citation Format

Share Document