The profitis llias deposit, milos island, greece: a case study of boiling in an epithermal system recorded by stable isotope and fluid inclusion data

摘要

Stable isotope (#delta#D and #delta#~(18)O) and microthermometric data are presented for the Profitis Ilias adularia-sericite-type epithermal gold deposit on Milos Island, Greece. The deposit was discovered by Midas Enterprise SA, and estimated reserves are 5 million tonnes grading at 4.4 g/t Au and 43 ppm Ag.Microther-mometric data show that the system boiled. Stable isotope ratios were determined on inclusion-fluids (#delta#D and #delta#~(18)O) and vein quartz (#delta#~(18)O). The inclusion-fluid data show fractionation trends consistent with single-stage steam separation and are broadly comparable to the currently active Milos geothermal system. The trends and comparisons in the fluid-ineral data are more difficult to interpret. This suggests that data derived by analysing both #delta#D and #delta#~(18)O on inclusion-fluids can provide a better framework for interpreting fluid processes in epithermal systems than current methodologies based on calculating #delta#~(18)O from fluid-quartz equilibria.