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J. Wakefield
The structural and metamorphic evolution of the Pikwe Ni-Cu sulfide deposit, Selebi-Pikwe, eastern Botswana
Economic Geology and the Bulletin of the Society of Economic Geologists (October 1976), 71(6):988-1005
Abstract:
The Pikwe Ni-Cu orebody is an Archean stratabound massive sulfide deposit associated with amphibolite host rocks of troctolitic composition. A small ultrabasic pod in the host amphibolite contains dumbbell-shaped sulfide blebs demonstrating that the ore was emplaced as an immiscible sulfide magma. The orebody was subsequently involved in a series of high-grade tectono-metamorphic events during the evolution of the Limpopo orogenic belt (2,660 to 2,000 m.y.). During the first metamorphic event sulfide/silicate reactions resulted in textural and mineralogical changes in the host amphibolite, the most notable of which is the development of large almandine-rich garnets.Polyphase deformation produced a sequence of ore textures including contorted-inclusion sulfide, foliated sulfide, and breccia sulfide. Detailed study of the regional structural geology has enabled the ore textures to be related to regional structural and metamorphic events. The orebody appears to have partially retained its pretectonic morphology despite its complex structural history.
Index Terms/Descriptors:
Africa; amphibolites; Archean; Botswana; composition; copper ores; data; east; economic geology; genesis; host rocks; igneous processes; Limpopo Belt; metal ores; metamorphic rocks; metamorphism; nickel ores; ore deposits; petrography; petrology; Pikwe; polymetallic ores; Precambrian; Selebi; Southern Africa; stratabound; sulfides; textures
Latitude & Longitude:
S27°00'00" -
S17°40'00" and
E20°00'00" -
E29°30'00" (Search for maps and images at Alexandria Digital Library)
GeoRef, Copyright 2006, American Geological Institute. Abstract, Copyright, Society of Economic Geologists
Copyright © 1976 by the GeoScienceWorld.