Comparative studies on fluid inclusion in different depths and ore genesis of the Sanshandao gold deposit, Jiaodong Peninsula

Sanshandao gold deposit, located in the north west of Jiaodong Peninsula, is a typical highly fractured and altered disseminated gold system. Petrography and fluid inclusion study on the altered wall rocks and gold ores from different depths (more than 2km) of the deposit indicate that the Sanshandao gold deposit is formed of similar gold-bearing fluids, characterized by H2O-CO2-NaCl +/- CH4 with homogenization temperature (170 similar to 330 degrees C) and pressure conditions (50 similar to 255MPa) during the main gold mineralized stage. The carbon, oxygen, hydrogen and sulfur isotope data show that ore fluids are derived from magmatic origin, most likely sourced from mafic to intermediate (likes. Water-rock interaction led to more crustal fluids with greater input of carbon and sulfur from the crust in the ore fluids. A variety of fluid processes have been responsible for gold precipitation including water-rock interaction and fluid immiscibility caused by cooling and change of mineralizing stress possibly. Additionally, chemisorption's processes in the interface between the fluid and sulfides may have further enhanced the deposition of the gold, particularly on the surfaces of these sulfide minerals.