Setting of epithermal Au deposits in a modern volcanic island arc setting, Milos, Greece: Implications for mineral exploration

摘要

The western part of Milos Island, Greece, comprises a compositionally and texturally diverse succession of calc-alkaline volcanic rocks that record a transition from a relatively shallow but dominantly below-wave-base setting to a subaerial one. The Upper Pliocene, mainly felsic-intermediate volcanic succession is dominated by lava domes and syn-volcanic intrusions, which are interleaved with volcaniclastic and sedimentary units. The succession contains several significant epithermal gold deposits that display a range of textural, mineralogical, and compositional characteristics. The majority of these epithermal Au ores occur within and at the lop of a very thick interval of rhyolitic pumice breccia generated by explosive arc volcan-ism, and are temporally and spatially associated with felsic cryptodomes (intrusions). We interpret the pa-laeogeography during mineralisation to have comprised scattered islands (volcanic domes) flanked by shallow-marine areas. Facies models presented in this research provide new data on the facies architecture of felsic-intermediate arc volcanoes that have high potential as hosts for precious ore deposits.