Geology, Geochemistry, Stable Isotope, and Fluid Inclusion Investigation of the Iron Oxide-Gold Mineralization in Bakir Tepe, Kangal-Sivas, East-Central Turkey~1

摘要

The Bakir Tepe area is characterized by four different lithologic units of Devonian-Carboniferous age. These units, from bottom to top, are metasiltstone, metacarbonate, metasandstone, and metaquartz sandstone. Metamorphic rocks in the study area are tectonically overlain by the recrys-tallized Mesozoic Munzur limestone. Iron oxide-gold mineralization in the Bakir Tepe area occurs in two different localities. The first is an alteration zone, which was formed at the thrust contact of metasiltstone with metacarbonate and metasandstone; the second locality is in metaquartz sandstone. The dominant minerals are quartz + hematite/magnetite + - pyrite + - gold in veins of various lengths and widths. Magnetite occurred after hematite, along fractures in hematite. Oxygen isotope data (delta~18O velence 6.2-13.3 per thousand) from fluids in equilibrium with quartz, and hydrogen isotope data (delta D velence -55 to -75 per thousand) from fluid inclusions trapped in quartz, indicate that the hydro-thermal fluids responsible for formation of the gold mineralization were dominated by metamorphic-derived waters. Hydrothermal solutions were of the NaCl-CO_2-H_2O type. Salinity values as NaCl equivalent wt percent range between 34 and 39. Total homogenization temperatures range between 132 and 382 deg C in secondary L+V inclusions, and 237 to 324 deg C in primary L+V+H inclusions. Calculated temperatures of vein formation using oxygen isotopes in quartz-hematite mineral pairs yields formation temperatures between 200 and 330 deg C, consistent with the fluid inclusion measurements.