GENESIS OF TWO DIFFERENT TYPES OF GOLD MINERALIZATION IN THE LINGLONG GOLD FIELD, CHINA: CONSTRAINS FROM GEOLOGY, FLUID INCLUSIONS AND STABLE ISOTOPE

摘要

(1) Deep-seated magmatic water may be the source of the ore-forming fluids. The fluid gradually blended with shallower meteoric water during mineralization. The ore-forming fluids initially had the characteristics of medium-high temperature, were enriched in CO_2, and had medium-low salinity. They finally evolved into low temperature, CO_2-free, low salinity, and meteoric water-dominated fluids in the late stage. (2) The mineralization of the Dongfeng gold deposit resulted from intense water-rock interaction between the H_2O?CO_2?NaCl fluids and wallrocks in the first-order fault, whereas precipitation of gold is possibly a consequence of phase separation or boiling of the H_2O?CO_2?NaCl fluids in response to pressure and temperature fluctuations in the open space of the secondary faults within the Linglong gold deposit. (3) Large-scale gold mineralisation in the Jiaodong region occurred during tectonic regime inversion and lithosphere thinning.