The Aulneau Batholith; Archean diapirism preceded by coalescence of granitoid magma at depth

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doi: 10.1016/0301-9268(91)90093-P
Authors:Ayres, L. D.; Halden, N. M.; Ziehlke, D. V.
Author Affiliations:Primary:
University of Manitoba, Department of Geological Sciences, Winnipeg, MB R3T 2N2, Canada
N.M. Inst. Mining and Technol., United States
Volume Title:Precambrian granitoids; petrogenesis, geochemistry and metallogeny
Volume Authors:Haapala, Ilmara, editor; Condie, Kent C.
Source:Precambrian Research, 51(1-4), p.27-50; Symposium on Precambrian granitoids; petrogenesis, geochemistry and metallogeny, Helsinki, Finland, Aug. 14-17, 1989, edited by Ilmara Haapala and Kent C. Condie. Publisher: Elsevier, Amsterdam, International. ISSN: 0301-9268
Publication Date:1991
Note:In English. 31 refs.; illus. incl. 10 anal., 2 tables, geol. sketch map
Summary:This oval, multiphase batholith in SW Ontario comprises 29 intrusive phases and complexes consisting mainly of leucocratic tonalite- granodiorite, the sequence of which has been established from structural, textural, mineralogical and contact evidence. The phases form five, asymmetrically distributed groups linked by similarities in spatial distribution, structure and composition. In order of apparent decreasing age these are: 1) early gneissic tonalite, 2) gabbro-diorite, 3) biotite trondhjemite-granodiorite, 4) hornblende-biotite-trondhjemite-granodiorite and 5) late granodiorite-granite. The granitic phases seem to be related by fractional crystallization whichoccurred in a deep chamber produced by partial melting of lower crust or upper mantle. Small batches of evolved magma were assembled at an intermediate crustal depth over at least 7 m.y. to produce the present complex phase distribution. Phase groups exhibit compositional overlap, each one apparently representing repetition of fractionation events at depth triggered by addition of new magma to, or magma movement within the chamber, rather than progressive evolution. The batholith subsequently rose up to be emplaced into a slightly older basaltic sequence as a largely solid diapir. [R.E.S.]
Subjects:Accessory minerals; Archean; Batholiths; Chemical composition; Crust; Diapirism; Diorites; Fractional crystallization; Gabbros; Granites; Granodiorites; Igneous rocks; Intrusions; Lower crust; Magma chambers; Magmas; Mantle; Metals; Modal analysis; Partial melting; Plutonic rocks; Precambrian; Rare earths; Spatial distribution; Tonalite; Trondhjemite; Upper mantle; Canada; Canadian Shield; Eastern Canada; North America; Ontario; Superior Province; Aulneau Batholith
Coordinates:N485000 N500000 W0933000 W0951000
Abstract Numbers:92M/0883
Record ID:1993000827
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom, Reference includes data from PASCAL, Institute de l'Information Scientifique et Technique
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