【摘要】 为了解四川西部夏塞银多金属矿区黑云母二长花岗岩形成和矿化发生的时代及成矿物质来源,测定了该矿区绒依措和若洛隆花岗岩的Rb_Sr年龄和钾长石、黑云母及主要银矿化阶段石英的40Ar/39Ar年龄及矿石的硫、铅同位素组成。花岗岩的结晶年龄约为93Ma,银矿化年龄约为75Ma。矿石硫可能源于花岗岩,但不能排除源于弱沉积围岩的可能性;矿石、花岗岩和弱变质沉积围岩的铅同位素组成相似,铅主要源于上地壳,少量源于下地壳。更多还原

【Abstract】 In this paper, the authors obtained Rb_Sr isochron ages of the Rongyicuo and Ruoluolong biotite monzonite batholiths and 40Ar/ 39Ar ages of K_feldspar and biotite in the granite of the ore district, dated quartz from the main silver mineralization and determined sulfur and lead isotope compositions of the ore minerals so as to understand timing and origin of ore materials in the Xiasai silver polymetallic deposit of western Sichuan. The crystallization timing of the Rongyicuo and Ruoluorong granite batholiths are approximately 93 Ma. The timing of silver mineralization is about 75 Ma. Sulfur of the ore is likely from granite, but the possibility from the lower metamorphic sediments cannot be excluded. Ores, granite and lower metamorphic sediments are similar to each other in lead isotope composition, suggesting that lead was mostly derived from the upper crust and subordinately from the lower crust. It is considered that the silver polymetallic ores were deposited in the NW_trending faults in the outer contact zone of the granite batholith through the mixture of hydrothermal fluids fractioned by crystallizing granite magma and hydrothermal fluids circulating in the country rocks as a result of elevated geothermal grade during the intrusion of the granite. The silver_polymetallic mineralization has close genetic relationship with the granitic magmatism.更多还原