浙西金鸡岩金矿床成矿特征与成矿机理研究

STUDY ON FEATURES AND METALLOGENIC MECHANISM OF JINJIYAN GOLD DEPOSIT, WEST ZHEJIANG PROVINCE

对浙西金鸡岩金矿进行了流体包裹体、岩石和矿石地球化学研究，以阐明其成矿特征和成矿机理．金鸡岩金矿是由多阶段成矿作用形成的，第一阶段以钼矿化为主，成矿温度较高；第二和第三阶段以金矿化为主，成矿温度较低．该金矿的成矿压力小、深度浅．成矿流体具低盐度、弱酸性及较高矿化度的特点，其中尚有大量大气水的混入．区内的前寒武纪浅变质岩系属于原始矿源层，而中生代火山岩，特别是次火山岩属于直接矿源岩．就成矿机理来看，金主要是呈金硫络合物形式迁移的，其次是被硅胶吸附呈胶体状态迁移的，而成矿流体的温度和压力下降、ｐＨ值降低以及溶液的氧化还原电位改变是导致金沉淀的重要因素．区内胶体金的沉淀主要是由于温度的降低和电解质的加入引起凝胶作用，使金随硅胶一同沉淀的．

A geochemical study of the fluid inclusions, rocks and ores in the Jinjiyan gold deposit attributes to demonstration of its metallogenic features and mechanism. The deposit is formed by three stages of metallogeny. The first stage is dominated by Mo mineralization with higher temperature, while the second and third by Au mineralization with lower temperature. The gold deposit is low in metallogenic pressure and shallow in metallogenic depth. The metallogenic fluid in the deposit, into which a lot of meteorological water is introduced, has lower salinity and acidity and higher degree of mineralization. The Precambrian epimetamorphic rock series is the primary source bed, while the Mesozoic volcanic and subvolcanic rocks are the direct source rock. With regards to metallogenic mechanism of the deposit, gold is transferred first in the form of gold sulphur complex compounds and second in the form of silicon colloids. The drop in temperature and pressure and pH and variation in Eh of the metallogenic fluid may be the most important factor resulting in gold precipitation. Similarily, the temperature lowering and dielectric adding may lead to gelatification of the silicon colloids, resulting in precipitation of gold in them.