论文部分内容阅读
西藏冈底斯矿带发育大量斑岩铜钼矿床及铜铅锌多金属矿床,形成斑岩铜矿带及多金属矿带。过去的工作表明,冈底斯带南部矿床同位素年龄多小于30Ma,形成于碰撞期后伸展环境。本文测定了冈底斯矿带南缘克鲁-冲木达矽卡岩型铜(金、钼)矿集区桑布加拉矽卡岩型铜(金)矿化岩体锆石LA-ICP-MSU-Pb年龄及锆石Ce4+/Ce3+比值。矿化岩体锆石U-Pb年龄:92.1±0.6Ma,MSWD=1.0,锆石Ce4+/Ce3+比值在90～562之间,平均值为287。锆石Ce4+/Ce3+比值和玉龙矿带含矿岩体锆石的比值基本一致,显示矽卡岩矿化岩体岩浆氧逸度较高。印度板块与欧亚板块碰撞时间在65～45Ma之间,桑布加拉矽卡岩型铜矿化岩体锆石U-Pb年龄表明冈底斯带不但发育碰撞期后大规模成矿作用,也发育与洋壳俯冲构造岩浆事件有关的成矿作用。这为冈底斯矿带洋壳俯冲有关矿床的寻找提供了依据。
A large number of porphyry copper-molybdenum deposits and copper-lead-zinc polymetallic deposits are developed in the Gangdese ore belt in Tibet, forming porphyry copper ore belts and polymetallic ore belts. Past work shows that the isotopic ages of southern deposits in the Gangdese belt are less than 30 Ma, forming after the collision period. In this paper, we measured the zircon LA-ICP of the Zambu-Chongmuda skarn type copper (gold and molybdenum) mineralization in the southern margin of the Gangdese ore belt -MSU-Pb age and zircon Ce4 + / Ce3 + ratio. The zircon U-Pb ages of mineralized rocks are 92.1 ± 0.6Ma, MSWD = 1.0, and the Ce4 + / Ce3 + ratios of zircons are between 90 and 562 with an average of 287. The Ce4 + / Ce3 + ratio of zircons is basically the same as the ratio of zircons in the ore-bearing rock masses of the Yulong ore belt, indicating that the skarn oxygenates of the skarn mineralized rocks are higher. The collision time between India plate and Eurasian plate is between 65 and 45 Ma. The zircon U-Pb ages of the Sambuca skarn copper mineralized rock indicate that the Gangdese belt not only developed large-scale mineralization after the collision period, Mineralization related to tectonic magmatism in the oceanic crust is also developed. This provides a basis for the prospecting of ore deposits in the subduction of the oceanic crust at Gangdese.