Nd-Sr isotope systematics of Nicola Group volcanic rocks, Quesnel Terrane

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doi: 10.1139/e95-037
Authors:Smith, Alan D.; Brandon, Alan D.; Lambert, Richard St. John
Author Affiliations:Primary:
University of Alberta, Department of Geology, Edmonton, AB, Canada
University of Oregon, United States
Volume Title:special issue in memory of Richard St John Lambert—Un numéro spécial en mémoire de Richard St John Lambert
Volume Authors:Brandon, Alan D., prefacer; Goles, Gordon G.
Source:A special issue in memory of Richard St John Lambert—Un numéro spécial en mémoire de Richard St John Lambert, prefaced by Alan D. Brandon and Gordon G. Goles. Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre, 32(4), p.437-446. Publisher: National Research Council of Canada, Ottawa, ON, Canada. ISSN: 0008-4077
Publication Date:1995
Note:In English with French summary. 39 refs.; illus., incl. 2 tables, geol. sketch map
Summary:These volcanic rocks in S British Columbia belong to an arc built on the W margin of the Quesnel terrain in the late Triassic to early Jurassic. Low-K to high-K compositional types define a Rb-Sr isochron of 222 ± 15 m.y. with initial 87Sr/86Sr 0.70367 ± 2; the corresponding Nd isotopic composition of these samples (εNd(222 m.y.) +5.1 to +7.8) fall within the range for early Mesozoic island arcs. A comparable range of εNd(222 m.y.) (+5.0 to +7.9) in picrite-shoshonite samples precludes generation of increasingly potassic magmas by progressive metasomatism of the mantle wedge alone. Source-region heterogeneity, possibly imparted by changes in the composition of subducted slab components or interaction with amphibole or phlogopite in the source remnant of an earlier (Permian) arc on the Quesnel terrain, is required to account for the observed geochemical differences. Crustal contamination is severely limited by the high εNd values, so that continental basement now underlying the terrain is a likely artefact of later terrain obduction. [R.A.H.]
Subjects:Absolute age; Alkaline earth metals; Dates; Facies; Geochemical profiles; Geochemistry; Heterogeneity; Isochrons; Isotope ratios; Isotopes; Lithogeochemistry; Magmas; Major elements; Mesozoic; Metals; Metamorphic rocks; Metamorphism; Metavolcanic rocks; Nd-144/Nd-143; Neodymium; Nicola Group; Rare earths; Rb/Sr; Sr-87/Sr-86; Stable isotopes; Strontium; Terranes; Trace elements; Triassic; British Columbia; Canada; Quesnellia Terrane; Western Canada; Southern British Columbia
Coordinates:N490000 N513000 W0103000 W1213000
Abstract Numbers:96M/654
Record ID:1995049106
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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