Canadian Journal of Earth Sciences
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Fossil biotas from the Okanagan Highlands, southern British Columbia and northeastern Washington State: climates and ecosystems across an Eocene landscape The late Early to early Middle Eocene Okanagan Highlands fossil sites, spanning ~1000 km northsouth (northeastern Washington State, southern British Columbia) provide an opportunity to reconstruct biotic communities across a broad upland landscape during the warmest part of the Cenozoic. Plant taxa from these fossil sites are characteristic of the modern eastern North American deciduous ... ... hiện toàn bộ
Canadian Journal of Earth Sciences - Tập 42 Số 2 - Trang 167-185 - 2005
A study of the isotopic abundance of boron from various sources The absolute ratio of 11 B/10 B has been determined for boron from different terrestrial sources with a precision of 0.2% (two standard errors) and a reproducibility of 0.2% (half-range). Values fall in the range 4.108 to 3.987 (i.e. 3% variation) and give a corresponding range in the boron atomic weight of 10.814 to 10.810 (0.04% variation). The ab... ... hiện toàn bộ
Canadian Journal of Earth Sciences - Tập 5 Số 4 - Trang 921-927 - 1968
U–Pb dating of monazite and its application to geological problems Monazite is an underutilized mineral in U–Pb geochronological studies of crustal rocks. It occurs as an accessory mineral in a wide variety of rocks, including granite, pegmatite, felsic volcanic ash, felsic gneiss, pelitic schist and gneiss of medium to high metamorphic grade, and low-grade metasedimentary rocks, and as a detrital mineral in clastic and metaclastic sediments.In geochrono... ... hiện toàn bộ
Canadian Journal of Earth Sciences - Tập 27 Số 11 - Trang 1431-1450 - 1990
Tectonic evolution of the western Superior Province from NATMAP and Lithoprobe studies Five discrete accretionary events assembled fragments of continental and oceanic crust into a coherent Superior craton by 2.60 Ga. They exhibit similar sequences of events at ~10 million year intervals: cessation of arc magmatism, early deformation, synorogenic sedimentation, sanukitoid magmatism, bulk shortening, regional metamorphism, late transpression, orogenic gold localization, empl... ... hiện toàn bộ
Canadian Journal of Earth Sciences - Tập 43 Số 7 - Trang 1085-1117 - 2006
Oxygen Isotope Studies of Fresh and Weathered Submarine Basalts The 18 O/16 O ratios of fresh unmetamorphosed basalts from the Reykjanes, Mid-Atlantic, and Gorda Ridges and the East Pacific Rise fall in a narrow range of 5.5–5.9‰ (SMOW), identical to those of basalts from oceanic islands. Large plagioclase xenocrysts in some of the basalts are not in isotopic equilibrium with coexisting olivine. The basalts reac... ... hiện toàn bộ
Canadian Journal of Earth Sciences - Tập 9 Số 2 - Trang 172-184 - 1972
Neoarchean trans-subprovince sediment transport in southwestern Superior Province: sedimentological, geochemical, and geochronological evidence At ~2700 Ma volcanism spawned by northward-directed subduction under Wabigoon subprovince, Canadian Shield, fed sediment into an adjacent fore-arc basin – trench system. Volcanically active island arcs to the south (Wawa subprovince) were transported northward during this interval and at ~2690 Ma collided with the accretionary complex (Quetico subprovince). Metamorphosed sedimentary units... ... hiện toàn bộ
Canadian Journal of Earth Sciences - Tập 43 Số 7 - Trang 1055-1070 - 2006
Structural evolution of the Hemlo greenstone belt in the vicinity of the world-class Hemlo gold deposit A complex history of volcano-sedimentary deposition, polyphase strain, multiple intrusive events, and various stages of porphyroblastesis is indicated for the Hemlo gold deposit area within the Hemlo greenstone belt. Structural elements can be assigned to at least six stages of development (D1 D6 ). D1 generated small-scale fol... ... hiện toàn bộ
Canadian Journal of Earth Sciences - Tập 40 Số 3 - Trang 395-430 - 2003
The age of the Gunflint Formation, Ontario, Canada: single zircon UPb age determinations from reworked volcanic ash The Gunflint Formation, a Paleoproterozoic chemicalclastic sedimentary assemblage outcropping to the immediate northwest of Lake Superior, became famous in 1954 as containing the oldest fossil assemblage known at that time. Older microfossils have since been discovered, but the Gunflint procaryotes remain one of the most diverse Precambrian fossil communities. The finding of possible mul... ... hiện toàn bộ
Canadian Journal of Earth Sciences - Tập 39 Số 7 - Trang 1085-1091 - 2002
Oxygen Isotope Geochemistry of Submarine Greenstones Most submarine greenstones recovered from the North Mid-Atlantic Ridge range in δ18 O from 2.8 to 6.8‰ (SMOW). An extremely light rock. (δ18 O = −7.1‰), was also analyzed, but it might be an ice rafted erratic. The heavier ones, up to 8‰, are probably weathered. On the average, the δ18 O of 14 greenstones is slightly lower than t... ... hiện toàn bộ
Canadian Journal of Earth Sciences - Tập 9 Số 5 - Trang 471-478 - 1972
Sediment- and basalt-hosted regoliths in the Huronian supergroup: role of parent lithology in middle Precambrian weathering profiles Weathering profiles developed side-by-side on sandstone and a mafic dike provide an unusual opportunity to examine the role of parent rock bulk composition in the chemical evolution of middle Precambrian regoliths. Because the profiles are adjacent to one another, differences in topography can be eliminated in accounting for differences in the chemical evolution of the two profiles. Both ... ... hiện toàn bộ
Canadian Journal of Earth Sciences - Tập 30 Số 1 - Trang 60-76 - 1993
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