The Mineral Paragenesis and Metamorphic Status of Garnet-hornblende-pyroxene-scapolite Gneiss from Ghana (Gold Coast)

O. von Knorring and W. Q. Kennedy
Dept. of Geology, University of Leeds.

Summary: The main minerals (garnet, pyroxene, hornblende, and scapolite) in certain Dahomeyan (Archaean) garnet-hornblende-pyroxene-scapolite gneisses from Ghana have been separated and analysed. Both the garnet and the pyroxene show marked eclogitic affinities, and the rocks are considered to occupy a transitional position between the amphibolite and eclogite facies. The scapolite is a sulphatic variety containing more than 4 % SO3 and is believed to be a product of autometasomatism. A revised scheme for the distribution of mineral facies within the temperature-pressure field of metamorphism is proposed.

Mineralogical Magazine; June 1958 v. 31; no. 241; p. 846-859; DOI: 10.1180/minmag.1958.031.241.04
© 1958, The Mineralogical Society
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