Skip to Main Content
Book Chapter

Fe-Ti Basalts, High Silica Rhyolites, and the Role of Magmatic Heat in the Genesis of the Kam-Kotia Volcanic-Associated Massive Sulfide Deposit, Western Abitibi Subprovince, Canada

By
C. Tucker Barrie
C. Tucker Barrie
Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario, Canada K1A 0E8
Search for other works by this author on:
John Pattison
John Pattison
Falconbridge Exploration Limited, 571 Moneta, P.O. Box 1140, Timmins, Ontario, Canada P4N 7H9
Search for other works by this author on:
Published:
January 01, 1999

Abstract

The Kam-Kotia volcanic-associated massive sulfide deposit (6.4 million tons, 1.1% Cu, 1.2% Zn, 0.1 oz/t Ag) is the largest of four deposits in the Late Archean Kamiskotia district. It occurs within a 4-km-thick bimodal stratigraphy, 2 km above a cogenetic and coeval gabbroic complex and accompanying fel-sic intrusion.

The composition and nature of the mafic and felsic volcanic rocks change from the stratigraphic foot-wall to the hanging wall in the Kam-Kotia mine area. Fe-Ti basalts—iron, titanium, and incompatible element-enriched tholeiitic basalts—are volumetrically minor in the footwall where they occur only as relatively thin (<5 m) sills and dikes. The ore horizon is cut by Fe-Ti basalt sill-flow units with peperite-textured upper contacts locally. In the hanging wall, Fe-Ti basalt units occur as 20- to 200-m-thick flows. The thickest of these are immediately upsection from the Kam-Kotia ore horizon and suggest ponding in a topographic depression. Two distinctive, mafic lapilli-bearing, intermediate and felsic tuff units are present along strike with, and ∼100 to 200 m upsection from, the Kam-Kotia ore horizon and are traceable for 5 km along strike. The mafic lapilli fragments are tholeiitic and approach Fe-Ti basalt compositions, and they have quenched rims and popcorn- or fiammelike textures. These units represent mixed magma, Plinian-type eruptions in a relatively shallow subaqueous setting. Rhyolite units change compositionally across the ore horizon, with potassic- and rubidium-enriched rhyolite units present almost exclusively in the stratigraphic hanging wall.

Calculated magmatic temperatures decrease in the vicinity of the ore horizon, as documented by the MgO thermometer for mafic rocks and the zircon saturation geothemometer for felsic rocks. Least altered tholeiitic mafic rocks are principally in the footwall, with Mg/(Mg + Fe) 45 to 58 and estimated temperatures of 1,130° to 1,210°C (n = 67). Hanging-wall Fe-Ti basalts have Mg/(Mg + Fe) of 30 to 44 and lower temperatures of 1,080° to 1,130°C (60 of 65 samples). Ferroan tholeiitic basalts have Mg/(Mg + Fe) and temperatures that overlap with the other basalt types and are ubiquitous. For least-altered rhyolites that approximate liquid compositions, the highest temperatures of 940° to 980°C are calculated for samples within 250 m of Kam-Kotia ore horizon (32 of 36 samples), whereas almost all others have lower temperatures of 850° to 940°C.

During the time of metal deposition, shallow-level fractionation of a tholeiitic parent produced Fe-Ti basalt magmas, as recorded in the ferroan upper zone cumulates of Kamiskotia Gabbroic Complex. Mafic magmas cooled with fractionation, assisted by advective heat loss by convecting hydrothermal fluids. Fel-sic magma temperatures increased at this time due to increased proximity and conductive heat from the adjacent mafic magma chamber, and to mafic magma injections as recorded by the mixed magma tuffs, and decreased afterward. Extrusion of Fe-Ti basalts apparently quenched the sulfide-precipitating system responsible for the Kam-Kotia deposit and the other volcanic-associated massive sulfide deposits of the Kamiskotia district.

You do not currently have access to this article.

Figures & Tables

Contents

Economic Geology Monograph Series

The Giant Kidd Creek Volcanogenic Massive Sulfide Deposit, Western Abitibi Subprovince, Canada

Mark D. Hannington
Mark D. Hannington
Search for other works by this author on:
C. Tucker Barrie
C. Tucker Barrie
Search for other works by this author on:
Society of Economic Geologists
Volume
10
ISBN electronic:
9781629490052
Publication date:
January 01, 1999

GeoRef

References

Related

Citing Books via

Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal