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.
Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.112390 |
Date | January 2008 |
Creators | Clark, David, 1979- |
Publisher | McGill University |
Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
Language | English |
Detected Language | English |
Type | Electronic Thesis or Dissertation |
Format | application/pdf |
Coverage | Master of Science (Department of Earth and Planetary Sciences.) |
Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
Relation | alephsysno: 002762921, proquestno: AAIMR51080, Theses scanned by UMI/ProQuest. |
Page generated in 0.0023 seconds