Petrology of syenites from center III of the Coldwell alkaline complex, northwestern Ontario, Canada

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doi: 10.1139/e93-014
Authors:Mitchell, Roger H.; Platt, R. Garth; Lukosius-Sanders, Jurate; Artist-Downey, Maureen; Moogk-Pickard, Shelley
Author Affiliations:Primary:
Lakehead University, Department of Geology, Thunder Bay, ON, Canada
Volume Title:Canadian Journal of Earth Sciences Revue Canadienne des Sciences de la Terre
Source:Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre, 30(1), p.145-158. Publisher: National Research Council of Canada, Ottawa, ON, Canada. ISSN: 0008-4077
Publication Date:1993
Note:In English with French summary. 29 refs.; illus. incl. 3 tables, geol. sketch map
Summary:This centre consists of metaluminous hypersolvus syenites, which in order of intrusion are magnesiohornblende, contaminated ferroedenite, ferroedenite and quartz syenites. Contaminated syenites were formed by the assimilation of coeval basaltic volcanic rocks. The suite as a whole is characterized by a wide variety of amphiboles ranging in composition from magnesiohornblende through ferroedenite and ferrorichterite to arfvedsonite. Pyroxenes are rare and hedenbergite is present in significant amounts only in quartz syenite. Whole rock major element data indicate that the majority of the syenites do not represent liquid compositions. The syenites have high contents of Nb, Zr, Th, U, Y, and Ga and have the geochemical character of A- type granitic rocks. REE and other trace element abundances suggest that the quartz syenites cannot be differentiates of the magma that formed the ferroedenite systems. All syenites originated by the extensive fractional crystallization of mantle- derived basalt magma within the plutonic infrastructure of the complex. The syenite suite does not represent the differentiation products of a single batch of magma. Multiple intrusion, contamination, and brecciation of preexisting syenite plutons have resulted in the complex geological relationships characteristic of centre III. [R.E.S.]
Subjects:Alkalic composition; Assimilation; Brecciation; Fractional crystallization; Geochemistry; Igneous rocks; Intrusions; Magmas; Major elements; Metals; Petrology; Plutonic rocks; Pollution; Rare earths; Syenites; Trace elements; Canada; Coldwell Complex; Eastern Canada; Great Lakes region; North America; Ontario
Coordinates:N484500 N484500 W0863500 W0863500
Abstract Numbers:94M/1201
Record ID:1993016626
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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