Gold +/- Copper Endowment and Deposit Diversity in the Western Tethyan Magmatic Belt, Southeast Europe: Implications for Exploration

摘要

Major Au and Cu deposits in the Western Tethyan magmatic belt formed during two main periods of Cretaceous and Cenozoic magmatism. The Cretaceous deposits are dominantly Cu-Au porphyry, high-sulfidation epithermal, and volcanic massive sulfide deposits, whereas in the Cenozoic Cu is significant only in porphyry systems. However, the Cenozoic contains approximately three times greater total Au endowment (for Au deposits >0.5 million ounces), and also has a greater deposit diversity, including porphyry Au-Cu and Au-only deposits, high-, intermediate-, and low-sulfidation epithermal Au systems, and Au-rich carbonate replacement and sediment-hosted styles. The differences in endowment and deposit styles likely reflect regional-scale tectono-magmatic processes as well as local preservation and emplacement levels. The Cu +/- Au endowment of the Cretaceous is consistent with typical subduction-related arc environments and generation of talc-alkaline porphyry to high-sulfidation epithermal systems, whereas Au enrichment related to Cenozoic magmatism appears to be related to high-K calc-alkalic to shoshonitic compositions. In many of the Au-rich Cenozoic magmatic belts, there is geochemical evidence for sourcing subcontinental lithospheric mantle that was previously enriched by Cretaceous subduction-related metasomatism. Additional differences in Au endowment may reflect the preservation of shallow-level systems in the Cenozoic, particularly for the Au-rich Miocene porphyry deposits such as Kisladag and Bierly Vrch and the Apuseni porphyry Au-Cu deposits. However, in both the Cretaceous and Cenozoic, crustal exposure levels vary across the belt and cannot explain all the differences in Cu and Au endowment.