吉林延边天宝山矿集区的叠加成矿——来自同位素年代学证据   总被引：1，自引：1，他引：0  

孙振明  任云生  鞠楠  赵华雷  陈聪  孙宇超 《岩石学报》2014,30(7):2081-2091

天宝山大型多金属矿集区位于兴蒙造山带东缘,西拉木伦-长春断裂带与敦(化)-密(山)断裂带交汇部位的北东侧,已发现矽卡岩型Pb-Zn-Ag矿化(如立山和选厂后山)、隐爆角砾岩中的Pb-Zn-Ag矿化(如新兴)、沉积变质-热液改造型CuPb-Zn矿化(如东风南山)和热液脉型Mo矿化(如东风北山)等多种矿化类型。为建立该区的成岩成矿年代学格架,采用LAICP-MS单颗粒锆石U-Pb法,对立山成矿闪长岩与东风北山含矿黑云母石英闪长岩开展了同位素测年研究;并对东风北山钼矿床开展了辉钼矿Re-Os法测年。结果表明,立山闪长岩体与东风北山黑云母石英闪长岩体中锆石的加权平均年龄分别为266.2±3.9Ma(MSWD=14)和278.4±1.8Ma(MSWD=2.9),两岩体均属海西晚期岩浆事件的结果;东风北山钼矿床中6件辉钼矿样品的Re-Os模式年龄介于190.3±3.1Ma~194.6±2.8Ma,等时线年龄为192±3.1Ma,表明钼的成矿作用发生于燕山早期。立山铅锌矿化属接触交代型,成矿岩体的年龄基本代表成矿时代,所以立山铅锌矿床形成于海西晚期;东风北山钼矿床为热液脉型,虽然含矿岩体的侵位时代为海西期,但钼矿化发生于燕山早期,成矿与矿区深部或外围的燕山早期侵入体有关。因此,天宝山矿集区至少发生过海西期和燕山期两期大规模岩浆成矿事件。不同期次构造-岩浆-成矿作用的叠加应是该矿床矿化类型复杂、矿种多和规模大的主因。  相似文献   

Geochronology,geochemistry and Sr–Nd–Hf–S–Pb isotopes of the Early Cretaceous Taoxihu Sn deposit and related granitoids,SE China     

《Ore Geology Reviews》2017

The Taoxihu deposit (eastern Guangdong, SE China) is a newly discovered Sn polymetallic deposit. Zircon U-Pb dating yielded 141.8 ± 1.0 Ma for the Sn-bearing granite porphyry and 145.5 ± 1.6 Ma for the biotite granite batholith it intruded. The age of the granite porphyry is consistent (within error) with the molybdenite Re–Os isochron age (139.0 ± 1.1 Ma) of the Sn mineralization, indicating a temporal link between the two. Geochemical data show that the granite porphyry is weakly peraluminous, contain high Si, Na and K, low Fe, Mg, Ca and P, and relatively high Rb/Sr and low K/Rb values. The rocks are enriched in Rb, Th, U, K, and Pb and depleted in Ba, Sr, Ti and Eu, resembling highly fractionated I-type granites. They contain bulk rock initial ⁸⁷Sr/⁸⁷Sr of 0.707371–0.707730 and εNd(t) of −5.17 to −4.67, and zircon εHf(t) values from −6.67 to −2.32, with late Mesoproterozoic T_DM2 ages for both Nd and Hf isotopes. This suggests that the granite porphyry was likely formed by the partial melting of the crustal basement of Mesoproterozoic overall residence age with minor mantle input.δ³⁴S_CDT values of the Taoxihu chalcopyrite and pyrite range from 0.1 to 2.1‰ (average: 0.9‰), implying a dominantly magmatic sulfur source. The ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb and ²⁰⁸Pb/²⁰⁴Pb ratios of the Taoxihu sulfide ores are 18.497–18.669, 15.642–15.673 and 38.764–38.934, respectively, indicating a mainly upper continental crustal lead source with minor mantle contribution. The highly fractionated and reduced (low calculated zircon Ce⁴⁺/Ce³⁺ and Eu_N/Eu_N¹ values) nature of the ore-forming granitic magma may have facilitated the Sn enrichment and played a key role in the Sn mineralization. We propose that the ore-forming fluids at Taoxihu were of magmatic-hydrothermal origin derived from the granite porphyry, and that both the granite porphyry and the Sn mineralization were likely formed in an extensional setting, possibly related to the subduction slab rollback of the Paleo-Pacific Plate.  相似文献