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Nd-Sr-Pb isotopic studies of the southern Coast plutonic complex, southwestern British Columbia

Yao Cui and J. K. Russell
Nd-Sr-Pb isotopic studies of the southern Coast plutonic complex, southwestern British Columbia
Geological Society of America Bulletin (February 1995) 107 (2): 127-138

Abstract

Nd, Sr, and Pb isotopic analyses are presented for plutonic and volcanic rocks from a northeast-southwest transect across the southern Coast Plutonic Complex (CPC). Plutonic and volcanic rocks have initial epsilon (sub Nd) of +4.2 to +8.9 and initial (super 87) Sr/ (super 86) Sr ratios of 0.70244-0.704 83. Values of Pb isotopic ratios for the suite range from 18.23 to 19.03 for (super 206) Pb/ (super 204) Pb, from 15.43 to 15.67 for (super 207) Pb/ (super 204) Pb, and from 37.54 to 38.30 for (super 208) Pb/ (super 204) Pb. The isotopic data suggest that these rocks consist mainly of mantle-derived materials with little or no involvement of old continental material. There are no significant variations in Nd and Sr isotopic composition with rock type or age. Pb isotopic compositions are also independent of rock type and age except for (super 208) Pb/ (super 204) Pb, which, for a subset of volcanic rocks, rises slightly with decreasing age. Examined against position along the transect, the isotopic data are uniform except for a rise in initial (super 87) Sr/ (super 86) Sr toward the northeast defined by older metavolcanic rocks. Based on the Nd and Pb isotopic data, a number of igneous rocks from the southern CPC appear to have been derived strictly from partial melting of mantle material. Many intrusions, however, have isotopic compositions and t (sub DM) ages consistent with the combined effects of melting of mantle and subordinate anatexis of isotopically juvenile terranes (e.g., Wrangellia).


ISSN: 0016-7606
EISSN: 1943-2674
Coden: BUGMAF
Serial Title: Geological Society of America Bulletin
Serial Volume: 107
Serial Issue: 2
Title: Nd-Sr-Pb isotopic studies of the southern Coast plutonic complex, southwestern British Columbia
Affiliation: University of British Columbia, Department of Geological Sciences, Vancouver, BC, Canada
Pages: 127-138
Published: 199502
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 72
Accession Number: 1995-018609
Categories: Isotope geochemistryGeochronologyIgneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 6 tables, geol. sketch maps
N49°00'00" - N51°00'00", W123°30'00" - W122°30'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 199507
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