The Stukpan carbonatite in the Orange Free State Goldfield
Date
1993
Authors
Verwoerd W.J.
Weder E.E.W.
Harmer R.E.
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Abstract
The Stukpan Complex is interpreted to be an oval pipe-like body, 3.1 × 1.7 km in diameter, unconformably overlain by Karoo strata and a dolerite sill. One borehole penetrated an intrusive contact between fine-grained amphibole-rich calciocarbonatite and an alkaline amphibolite derived by fenitization from andesitic Ventersdorp lava. A second borehole encountered calciocarbonatite sills as well as red fenite and brecciated quartzite belonging to the Welkom Formation of the Central Rand Group. Geochemical logs show consistently high Sr contents in the carbonatite but low P, Nb, Zr, and REE. Despite erratic Cu and Ni values and sporadic sulphides no indications of economic mineralization have been found. Rb-Sr mineral separate geochronology yielded a well-constrained isochron age of 1354 ± 11 Ma for the carbonatite and confirmed a Ventersdorp (2700 Ma) age for the alkaline amphibolite. -from Authors
Description
Keywords
carbonatite, geochemistry, petrogenesis, petrology, South Africa, Orange Free State, Stukpan Complex
Citation
South African Journal of Geology
96
3
96
3