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Extreme fractionation and deformation of the leucogranite-pegmatite suite at Red Cross Lake, Manitoba, Canada; IV, Mineralogy

Petr Cherny, David K. Teertstra, Ron Chapman, Julie B. Selway, Frank C. Hawthorne, Karen Ferreira, Leonard E. Chackowsky, Xian-Jue Wang and Robert E. Meintzer
Extreme fractionation and deformation of the leucogranite-pegmatite suite at Red Cross Lake, Manitoba, Canada; IV, Mineralogy (in Granitic pegmatites and their minerals; a second tribute to Petr Cerny, Miguel A. Galliski (editor), David London (editor), Milan Novak (editor) and Robert F. Martin (editor))
The Canadian Mineralogist (December 2012) 50 (6): 1839-1875

Abstract

Three types of subvertical pegmatitic leucogranites and pegmatites populate the Red Cross Lake pegmatite field, located in a greenstone belt of the Sachigo Subprovince, Manitoba, in the northwestern part of the Archean Superior Province of the Canadian Shield. Most of the leucogranites and pegmatites are geochemically rather primitive, but one of the leucogranites is lithium-enriched, and the most evolved lepidolite-rich pegmatites represent the most fractionated products of granitic differentiation known to date. The lepidolite pegmatites consist mainly of albite, quartz and muscovite to K-, Rb- or Cs-dominant lepidolite, subordinate Rb-rich K-feldspar and spodumene + quartz pseudomorphs after petalite, accessory spessartine, elbaite-rossmanite, beryl, pollucite, fluorapatite, amblygonite, oxide minerals of Ta, Nb, Ti, Sn, Sb and U, and rare zircon, lithiophilite and other phosphates, arsenopyrite, lollingite, stibarsen and bismuth. Along contacts with mafic metavolcanic rocks, a (Ca,Fe,Mg,Ti)- enriched assemblage carries, i.a., K-, Rb- or Cs-based annite to phlogopite dominant over holmquistite, Ca-Mg-Fe-rich tourmaline and garnet, and clinozoisite-epidote. Primary K-feldspar and secondary Rb-dominant feldspar show K/Rb as low as 1.9 and 0.25, respectively. Zoned muscovite-to-lepidolite crystals have K/Rb nearly equal 0.09 and K/Cs nearly equal 0.02 in the outer Li-rich parts. Spessartine, lithiophilite, elbaite, and (Nb,Ta) oxide minerals are almost devoid of Fe; Nb is locally extremely depleted relative to Ta. Zircon contains approximately 32.1 wt.% HfO (sub 2) , but wodginite is the main carrier of Zr and Hf. The lepidolite pegmatites underwent extensive shearing leading to mylonitization that did not, however, affect the chemical composition of any minerals except the partially recrystallized and re-equilibrated pollucite.


ISSN: 0008-4476
EISSN: 1499-1276
Coden: CAMIA6
Serial Title: The Canadian Mineralogist
Serial Volume: 50
Serial Issue: 6
Title: Extreme fractionation and deformation of the leucogranite-pegmatite suite at Red Cross Lake, Manitoba, Canada; IV, Mineralogy
Title: Granitic pegmatites and their minerals; a second tribute to Petr Cerny
Author(s): Cherny, PetrTeertstra, David K.Chapman, RonSelway, Julie B.Hawthorne, Frank C.Ferreira, KarenChackowsky, Leonard E.Wang, Xian-JueMeintzer, Robert E.
Author(s): Galliski, Miguel A.editor
Author(s): London, Davideditor
Author(s): Novak, Milaneditor
Author(s): Martin, Robert F.editor
Affiliation: University of Manitoba, Department of Geological Sciences, Winnipeg, MB, Canada
Pages: 1839-1875
Published: 201212
Text Language: English
Publisher: Mineralogical Association of Canada, Ottawa, ON, Canada
References: 102
Accession Number: 2013-032418
Categories: Igneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 18 tables
N55°02'60" - N55°07'60", W93°04'60" - W92°43'00"
Country of Publication: Canada
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, copyright, Mineralogical Association of Canada. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201320
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