Skip to Main Content
Book Chapter

Gold Mineralization in the Abitibi Greenstone Belt: End-Stage Result of Archean Collisional Tectonics?

By
C. Jay Hodgson
C. Jay Hodgson
Department of Geological Sciences, Queen’s University, Kingston, Ontario, Canada K7L 3N6
Search for other works by this author on:
J. V. Hamilton
J. V. Hamilton
Department of Geological Sciences, Queen’s University, Kingston, Ontario, Canada K7L 3N6
Search for other works by this author on:
Published:
January 01, 1989

Abstract

The Abitibi greenstone belt, the largest and best-preserved Archean granite-greenstone complex in the world, consists of five major lithologic assemblages which formed in four distinctive geotectonic environments. These comprise: (1) a tholeiitic and komatiitic assemblage formed in an oceanic extensional environment; (2) a calc-alkalic volcanic and volcanic-derived sedimentary rock assemblage formed in an island-arc environment; (3) an assemblage of craton-derived quartzose sedimentary rocks with interbedded komatiitic volcanic rocks formed on a passive continental margin; and (4) an assemblage of molasse-type sedimentary rocks, alkalic volcanic rocks, and felsic intrusions. The oceanic, arc, and continental margin assemblages were imbricated and tectonically stacked during the collision of a northward-moving continent and its attached marginal sediments with the arc, as a result of subduction of the intervening ocean crust. The molasse assemblage formed along the collisional suture zone. Interbedded alkalic volcanic rocks, syn- to postdeformational felsic intrusions, and the CO2-rich hydrothermal fluids responsible for widespread hydrothermal alteration and gold mineralization, all broadly part of this molasse assemblage, were generated by linked lower crust-mantle processes. The effect of the high density of the oceanic rocks on pressure-temperature conditions at the base of the tectonically thickened crust may have been instrumental in triggering the processes which resulted in auriferous fluids. Anatectic melts and gold ore-forming hydrothermal fluids were generated at depth as an end-stage manifestation of the collisional event. Rocks of the oceanic assemblage were the possible source of the gold. This model provides a rational and internally consistent explanation for the association of gold mineralization with greenstone belts, major faults, molasse-type sedimentary rock assemblages, felsic porphyry intrusions, and widespread hydrothermal alteration. Also, the model is consistent with the late timing of the mineralization in the geologic development of the Abitibi belt in particular, and both Precambrian and Phanerozoic greenstone belts in general.

You do not currently have access to this article.
Don't already have an account? Register

Figures & Tables

Contents

Economic Geology Monograph Series

The Geology of Gold Deposits: The Perspective in 1988

Reid R. Keays
Reid R. Keays
Search for other works by this author on:
W. R. H. Ramsay
W. R. H. Ramsay
Search for other works by this author on:
David I. Groves
David I. Groves
Search for other works by this author on:
Society of Economic Geologists
ISBN electronic:
9781629490014
Publication date:
January 01, 1989

GeoRef

References

Related

A comprehensive resource of eBooks for researchers in the Earth Sciences

Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal