Institution
Geological Survey of Canada
Government•Ottawa, Ontario, Canada•
About: Geological Survey of Canada is a government organization based out in Ottawa, Ontario, Canada. It is known for research contribution in the topics: Subduction & Terrane. The organization has 2824 authors who have published 7859 publications receiving 315412 citations. The organization is also known as: GSC.
Topics: Subduction, Terrane, Craton, Crust, Glacial period
Papers published on a yearly basis
Papers
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TL;DR: In this paper, the results of a study to develop natural zircon geochemical standards for calibrating the U-(Th)-Pb geochronometer and Hf isotopic analyses are reported.
Abstract: We report here the results of a study to develop natural zircon geochemical standards for calibrating the U-(Th)-Pb geochronometer and Hf isotopic analyses. Additional data were also collected for the major, minor and trace element contents of the three selected sample sets. A total of five large zircon grains (masses between 0.5 and 238 g) were selected for this study, representing three different suites of zircons with ages of 1065 Ma, 2.5 Ma and 0.9 Ma. Geochemical laboratories can obtain these materials by contacting Geostandards Newsletter.
4,845 citations
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TL;DR: A-type granites as mentioned in this paper were found to have high SiO2, Na2O+K2O, Fe/Mg, Ga/Al, Zr, Nb, Ga, Y and Ce, and low CaO and Sr.
Abstract: New analyses of 131 samples of A-type (alkaline or anorogenic) granites substantiate previously recognized chemical features, namely high SiO2, Na2O+K2O, Fe/Mg, Ga/Al, Zr, Nb, Ga, Y and Ce, and low CaO and Sr. Good discrimination can be obtained between A-type granites and most orogenic granites (M-, I and S-types) on plots employing Ga/Al, various major element ratios and Y, Ce, Nb and Zr. These discrimination diagrams are thought to be relatively insensitive to moderate degrees of alteration. A-type granites generally do not exhibit evidence of being strongly differentiated, and within individual suites can show a transition from strongly alkaline varieties toward subalkaline compositions. Highly fractionated, felsic I- and S-type granites can have Ga/Al ratios and some major and trace element values which overlap those of typical A-type granites. A-type granites probably result mainly from partial melting of F and/or Cl enriched dry, granulitic residue remaining in the lower crust after extraction of an orogenic granite. Such melts are only moderately and locally modified by metasomatism or crystal fractionation. A-type melts occurred world-wide throughout geological time in a variety of tectonic settings and do not necessarily indicate an anorogenic or rifting environment.
4,216 citations
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Curtin University1, University of Western Australia2, Lund University3, University of Adelaide4, Geological Survey of Canada5, Carleton University6, University of Brasília7, University of Bergen8, University of New Mexico9, Macquarie University10, Stockholm University11, University of Copenhagen12, Russian Academy of Sciences13
TL;DR: A brief synthesis of the current state of knowledge on the formation and break-up of the early Neoproterozoic supercontinent Rodinia and the subsequent assembly of Gondwanaland is presented in this paper.
2,790 citations
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TL;DR: The responses of the Northern and Southern Hemispheres differed significantly, which reveals how the evolution of specific ice sheets affected sea level and provides insight into how insolation controlled the deglaciation.
Abstract: We used 5704 14C, 10Be, and 3He ages that span the interval from 10,000 to 50,000 years ago (10 to 50 ka) to constrain the timing of the Last Glacial Maximum (LGM) in terms of global ice-sheet and mountain-glacier extent. Growth of the ice sheets to their maximum positions occurred between 33.0 and 26.5 ka in response to climate forcing from decreases in northern summer insolation, tropical Pacific sea surface temperatures, and atmospheric CO2. Nearly all ice sheets were at their LGM positions from 26.5 ka to 19 to 20 ka, corresponding to minima in these forcings. The onset of Northern Hemisphere deglaciation 19 to 20 ka was induced by an increase in northern summer insolation, providing the source for an abrupt rise in sea level. The onset of deglaciation of the West Antarctic Ice Sheet occurred between 14 and 15 ka, consistent with evidence that this was the primary source for an abrupt rise in sea level ~14.5 ka.
2,691 citations
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TL;DR: In this paper, a number of experiments have been conducted in order to study the equilibria between olivine and basaltic liquids and to try and understand the conditions under which OIVINE will crystallize.
Abstract: A number of experiments have been conducted in order to study the equilibria between olivine and basaltic liquids and to try and understand the conditions under which olivine will crystallize. These experiments were conducted with several basaltic compositions over a range of temperature (1150-1300 ° C) and oxygen fugacity (10-°.~s-10 -12 arm.) at one atmosphere total pressure. The phases in these experimental runs were analyzed with the electron microprobe and a number of empirical equations relating the composition of olivine and liquid were determined. The distribution coefficient o, (X~o/ (Xreo) K/~- i'~-Liq \ O1 t-XFeoJ (X~go) relating the partioning of iron and magnesium between olivine and liquid is equal to 0.30 and is independent of temperature. This means that the composition of olivine can be used to determine the magnesium to ferrous iron ratio of the liquid from which it crystallized and conversely to predict the olivine composition which would crystallize from a liquid having a particular magnesium to ferrous iron ratio. A model (saturation surface) is presented which can be used to estimate the effective solubility of olivine in basaltic melts as a fune¢ioa of temperature. This model is useful in predicting the temperature at which olivine and a liquid of a particular composition can coexist at equilibrium.
2,543 citations
Authors
Showing all 2844 results
Name | H-index | Papers | Citations |
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Robie W. Macdonald | 79 | 292 | 23460 |
James P. M. Syvitski | 74 | 304 | 28538 |
Richard S. Smith | 73 | 417 | 18976 |
Scott A. Mabury | 71 | 225 | 18776 |
Roy D. Hyndman | 69 | 231 | 16513 |
Randall R. Parrish | 68 | 212 | 16398 |
Kelin Wang | 68 | 328 | 16549 |
Timothy M. Kusky | 66 | 273 | 14576 |
John H. Adams | 66 | 354 | 16169 |
John J. Clague | 65 | 365 | 15390 |
John D. Milliman | 65 | 158 | 22454 |
Alan G. Jones | 63 | 287 | 13435 |
William Shotyk | 63 | 232 | 13658 |
David J.W. Piper | 60 | 364 | 11711 |
Donald W. Forsyth | 60 | 148 | 12865 |