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On the genesis of Archean granite through two-stage melting of the Quetico accretionary prism at a transpressional plate boundary

D. L. Southwick
On the genesis of Archean granite through two-stage melting of the Quetico accretionary prism at a transpressional plate boundary
Geological Society of America Bulletin (November 1991) 103 (11): 1385-1394

Abstract

Regional geologic relationships and geochemical data support the idea that late-stage biotite granite of the Lac La Croix type may have formed by partial melting of previously migmatized metasedimentary rocks in the Quetico subprovince of the Superior craton. The proposed parent material is an intimately layered rock composed of approximately half to two-thirds biotite schist and half to one-third granitoid leucosome; the bulk chemical attributes of such a material were estimated from detailed mapping and drilling of two large outcrops near Pearl Lake, Minnesota.Previous work has demonstrated that the granitoid leucosome of the layered migmatite is the intrusively injected product of partial melting of a metasedimentary protolith. Therefore the proposed derivation of the younger Lac La Croix-type granite from layered migmatite in effect represents a second distillation of granitic liquid from meta-sedimentary rocks that had been enriched ingranitic components in the first cycle of partial melting and melt migration. It is postulated that the implied two-stage melting of metasedimentary rocks was related to thermal consequences within the Quetico accretionary complex as tectonism along the Quetico-Wabigoon boundary alternated between subduction and transform kinematics during Late Archean time.


ISSN: 0016-7606
EISSN: 1943-2674
Coden: BUGMAF
Serial Title: Geological Society of America Bulletin
Serial Volume: 103
Serial Issue: 11
Title: On the genesis of Archean granite through two-stage melting of the Quetico accretionary prism at a transpressional plate boundary
Author(s): Southwick, D. L.
Affiliation: Minn. Geol. Surv., St. Paul, MN, United States
Pages: 1385-1394
Published: 199111
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 44
Accession Number: 1991-046980
Categories: Igneous and metamorphic petrologySolid-earth geophysics
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 5 tables, geol. sketch maps
N48°00'00" - N49°00'00", W94°00'00" - W90°00'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute.
Update Code: 1991
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