江西银山矿床是一个与火山-次火山热液有关的多金属矿床。文章通过对该矿床九区与铜金矿化有关的蚀变英安斑岩和石英斑岩中绢云母的^40Ar-^39Ar快中子活化年龄测试,获得蚀变英安斑岩中绢云母的坪年龄和等时线年龄分别为(178.2±1.4)Ma和(179.6±2.9)Ma;蚀变石英斑岩中2件绢云母样品的坪年龄和等时线年龄分别为(175.4±1.2)Ma和(175.3±1.1Ma),(176.2±5.1)Ma和(176.6±3.3)Ma。这些数据表明,银山多金属矿床铜金矿化的成矿时代为175~180Ma。该成果的获得对于进一步认识德兴地区乃至华南地区中生代的地球动力学背景具重要意义。
The Yinshan polymetallic deposit in jiangxi Province is a hydrothermal vein-type deposit closely related to Late jurassic felsic-intermediate volcanic-subvolcanic activities. The second stage of Cu-Au mineralization is associated with dacite porphyry. Sericites from dacite porphyry and quartz porphyry in the Cu-Au ore zone were analyzed by the ^40Ar-^39Ar fast-neutron activation dating technique, and the results yielded the plateau age and the isochron age of ( 178.2 ± 1.4) Ma and ( 179.6 ± 2.9) Ma respectively in altered &cite porphyry, and ( 175.4 ± 1.2) Ma and ( 176.2 ± 5.1 ) Ma, (175.3 ± 1.1) Ma and ( 176.6 ± 3.3) Ma respectively in altered quartz porphyry. It is held that the Cu-Au mineralization in the Yinshan deposit took place in 175 ~ 180 Ma, resulting from the tectonic extension related to multiple lithospheric extension in South China.