Geochemical and isotopic constraints on Palaeozoic orogenic gold endowment and crustal evolution of the south central Andes, NW Argentina.

BIERLEIN, F.P., COIRA, B. AND STEIN, H.

Beijing, China.

Congreso; 8th SGA Biennial Meeting.; 2005

Society for Geology Applied to Mineral Deposits

Major and trace element concentrations, and Nd isotope compositions of Ordovician volcano-intrusive rocks in the Puna of northwestern Argentina point to their formation in a pericratonic setting above thickened and evolved continental crust. Input from juvenile sources remained limited and there is no evidence for oceanic crust or the presence of a terrane-bounding suture in the region. In contrast to analogous terrains elsewhere in the Central Andes (e.g., in Peru and Bolivia), relatively minor orogenic gold mineralisation is known to occur in the Palaeozoic succession in northwestern Argentina. Possible explanations for the lack of more substantial orogenic gold endowment are considered herein. These include the absence of hydrated oceanic substrate in the Puna, lack of 1st-order conduits and the limited extent of crustal shortening and thickening during Ordovician orogenic events.