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Petrogenetic and economic significance of the whole-rock chemistry of ultramafic cumulates in the Cape Smith foldbelt, northern Quebec

The ultramafic cumulate rocks of the Raglan horizon in the Proterozoic Cape Smith fold belt of northern Quebec have a common parental liquid in equilibrium with olivine of Fo89 composition. Cumulate olivines have experienced a trapped liquid shift to lower forsterite composition proportionally to the fraction of trapped liquid in the cumulate. Anomalously low nickel contents in analyses of both olivine and whole-rock chemistries are observed only in cumulates with the most modal olivine and which are proximal to known Ni-Cu-(PGE) deposits. The calculated compositions of the trapped liquid fraction indicate that most of the Raglan cumulates formed from Fe-rich high-MgO basalts, which are restricted to the base of the Chukotat volcanic stratigraphy. We propose that a lower degree of adiabatic partial melting of a mantle source accounts for the Fe-rich nature of these parental liquids and may provide an explanation for the presence of numerous Ni-Cu-(PGE) deposits in the sills of the Raglan horizon.

Identiferoai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.112390
Date January 2008
CreatorsClark, David, 1979-
PublisherMcGill University
Source SetsLibrary and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada
LanguageEnglish
Detected LanguageEnglish
TypeElectronic Thesis or Dissertation
Formatapplication/pdf
CoverageMaster of Science (Department of Earth and Planetary Sciences.)
RightsAll items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated.
Relationalephsysno: 002762921, proquestno: AAIMR51080, Theses scanned by UMI/ProQuest.

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