Metamorphism of the country rocks hosting gold–sulfide-bearing quartz veins in the Paleoproterozoic southern Kibi-Winneba belt (SE-Ghana)
✍ Scribed by R Klemd; U Hünken; M Olesch
- Book ID
- 104354127
- Publisher
- Elsevier Science
- Year
- 2002
- Tongue
- English
- Weight
- 486 KB
- Volume
- 35
- Category
- Article
- ISSN
- 1464-343X
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✦ Synopsis
Many sections of Paleoproterozoic greenstone belts in the Birimian of Ghana are found to have experienced subgreenschist-to greenschist-facies metamorphism. However, mineral-chemical and textural examinations in combination with conventional geothermobarometry of metapelites and amphibolites from the southern Kibi-Winneba belt suggest peak amphibolite-facies conditions of 500-610 °C at 4.5-6 kbar. This is in accordance with peak-metamorphic P-T estimates of 490-580 °C at 4-6 kbar for Birimian rocks of the southern Ashanti belt [Precambrian Res. 98 (1999) 11] and the northwestern Sefwi belt [Geol. Jahrbuch, in press]. Hydrothermal alteration and gold mineralization in this region apparently has occurred during retrograde greenschist-facies conditions at temperatures of 400-540 °C as indicated by the sulfide paragenesis arsenopyrite-pyrite (with l€ o ollingite inclusions) and arsenopyrite-pyrrhotite. These data suggest that alteration and lode-gold mineralization occurred under post-peak-metamorphic conditions.