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Book Chapter

Origin of Chromite Seams in the Hartley Complex of the Great Dyke, Rhodesia

By
R. Bichan
R. Bichan
Robertson Research Co., Ltd., Llanddulas, Abergele, Denbighshire, U.K.,
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Published:
January 01, 1969

Abstract

The Great Dyke of Rhodesia consists of 4 ultrabasic lopolithic complexes, each of which can be divided into a series of synclinal units; these are numbered Unit 1, Unit 2, Unit 3, etc., from the top to the bottom of each lopolith. The present investigations, based on numerous diamond drill cores, is concerned with Unit 2 in the Hartley Complex of the Dyke and, in particular, with the origin of the two chromite seams it contains. A typical vertical section is: Unit 1, Gabbroic rocks; Unit 2, Pyroxenite, olivine in basal part—470 feet, Picrite and harzburgite—150 ft., Chromite Seam No. 1—10 in., Harzburgite—80 ft., Chromite Seam No. 2—14 in., Unit 3, Pyroxenite, etc.

Detailed examination has been made on the petrographic and stratigraphic relations of the two chromite seams and the contact of Units 2 and 3, and the chemical composition of whole rocks and co-existing chromite and olivine.

These studies indicate that Unit 2 was formed from two magmatic inflows, the first occurring before complete crystallization of the pyroxenites of Unit 3 had taken place and the second well before crystallization of the first inflow had been completed.

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Contents

Society of Exploration Geophysicists Geophysical Monograph Series

Magmatic Ore Deposits

H. D. B. Wilson
H. D. B. Wilson
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Society of Economic Geologists
Volume
4
ISBN electronic:
9781934969991
Publication date:
January 01, 1969

GeoRef

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