(GEUS) initiated a study of the origin and tectono-meta-morphic evolution of greenstone belts and important regio-nal structures in the central Godthåbsfjord region, southern West Greenland (Fig. 1; Hollis et al. 2004). Like other Ar-chaean belts worldwide, these greenstone belts are locally host to...
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| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.505.6727 http://www.geus.dk/publications/bull/nr7/nr7_p65-68.pdf |
| Summary: | (GEUS) initiated a study of the origin and tectono-meta-morphic evolution of greenstone belts and important regio-nal structures in the central Godthåbsfjord region, southern West Greenland (Fig. 1; Hollis et al. 2004). Like other Ar-chaean belts worldwide, these greenstone belts are locally host to gold mineralisation. Their complexity requires a com-bination of detailed geological mapping, geochemistry, pe-trographic work and geochronological studies to develop models of their geological setting, evolution and gold minerali-sation. Regional geology The greenstone belts in the Godthåbsfjord region represent remnants of Archaean intrusive and extrusive mafic rocks, and minor chemical and clastic sediments. These were once thought to be dismembered parts of the same greenstone belt, but are now known to belong to unrelated groups of differ-ent ages, occurring within several distinct continental crustal terranes – the Færingehavn, Akia and Tre Brødre terranes (Fig. 1; e.g. Schiøtte et al. 1988). These terranes were amal-gamated at 2950–2700 Ma (e.g. Friend & Nutman 2005). The 3850–3300 Ma Færingehavn terrane largely comprises early Archaean tonalitic orthogneiss, granite, ultramafic and gabbroic rocks, together with rocks of inferred supracrustal origin, all of which are intruded by mafic Ameralik dykes. The 3200–2975 Ma Akia terrane comprises orthogneiss and greenstones. The 2826–2750 Ma Tre Brødre terrane, which is in tectonic contact with the Færingehavn terrane in many parts of the central Godthåbsfjord region, and also with the Akia terrane (Fig. 1), is dominated by late Archaean (c. 2825 Ma) orthogneiss, but also includes metasedimentary and mafic volcanic rocks and gabbro-anorthosite. The boundary Greenstone belts in the central Godthåbsfjord region |
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