Michael T. Styles
Cliff D. Taylor
Roger M. Key
Wilfried Bauer Wilfried
A Vonimanitra Ralison Vonimanitra
Peter E. J Pitfield
2009
<p><span>Microchemical characterisation of bedrock and placer gold grains from six gold districts within the Archaean domains and intervening Neoproterozoic Anaboriana-Manampotsy belt of northern and east-central Madagascar show few opaque inclusions (e.g pyrrhotite, Bi tellurides) but wide range of Ag contents (40wt%). Some districts exhibit multiple source populations of grains. The ‘greenstone belt’ terranes have an orogenic gold signature locally with an intrusion-related to epithermal overprint. Proterozoic metasediments with felsic to ultramafic bodies yield dominantly intrusion-related gold. A high proportion of secondary gold (<0.5wt% Ag) is related to recycling of paleoplacers and erosion of post-Gondwana planation surfaces and indicates that some mesothermal gold systems were already partially to wholly removed by erosion by the PermoTriassic.</span></p>
application/pdf
en
James Cook University School of Earth & Environmental Studies. Economic Geology Research Unit
Gold deposit styles and placer gold characterisation in northern and east-central Madagascar
text