U-Pb geochronology of cassiterite and zircon from the Dulong Sn-Zn deposit: Evidence for Cretaceous large-scale granitic magmatism and mineralization events in southeastern Yunnan province, China
U-Pb geochronology of cassiterite and zircon from the Dulong Sn-Zn deposit: Evidence for Cretaceous large-scale granitic magmatism and mineralization events in southeastern Yunnan province, China
复制标题
DOI：
--
复制
发表时间：
2007
影响因子：
1.8
通讯作者：
Y. Liu;Zheng‐Xiang Li;H. Li;L. Guo;W. Xu;L. Ye;C. Li;D. Pi
中科院分区：
文献类型：
--
作者：
Y. Liu;Zheng‐Xiang Li;H. Li;L. Guo;W. Xu;L. Ye;C. Li;D. Pi
独龙锡锌矿床是中国最大的锡石硫化物矿床之一。由于缺乏可靠的地质年代学资料，关于该矿床的成因众说纷纭。通过锡石和锆石的U-Pb测年，首次确定了该矿床及相关晚燕山期花岗岩的岩浆和成矿年龄。满家寨剖面4个锡石样品的~(206)Pb/(238)U平均年龄为79.8±3.2Ma(MSWD=3.16), ~(238)U/~(204)Pb-~(206)Pb/~(204)Pb等时年龄为82.0±9.6Ma（MSWD=4.81）。满家寨剖面隐伏花岗岩锆石的平均~(206)Pb/~(238)U年龄为92.9±1.9Ma(N=10，MSWD=0.71)，同街剖面花岗斑岩露头锆石的平均~(206)Pb/~(238)U年龄为86.9±1.4Ma(N=9，MSWD=3.70)，均采用SHRIMP U-Pb法测定。这些年龄表明独龙锡锌矿床的锡（铜）成矿作用主要与晚白垩世岩浆热液事件有关。个旧（Sn）和白牛场（Ag）超大型矿床及其相关的燕山期花岗岩年代学资料表明，云南东南部白垩纪曾发生过大规模的花岗质岩浆活动和成矿事件，可能与晚中生代华南地块岩石圈伸展有关。
The Dulong Sn-Zn deposit is one of the largest cassiterite-sulfide deposits in China.There are different opinions regarding the genesis of this deposit,partly due to the lack of reliable geochronological data.We report here results of the first attempt to determine the magmatic and mineralization ages of this deposit and related late-Yanshanian granites through U-Pb dating of cassiterite and zircon.Four cassiterite samples from the Manjiazhai section yields a means~(206)Pb/(238)U age of 79.8±3.2Ma(MSWD=3.16), and a~(238)U/~(204)Pb-~(206)Pb/~(204)Pb isochronal age of 82.0±9.6Ma(MSWD=4.81)using the TIMS U-Pb method.Zircon from a concealed granite at the Manjiazhai section yielded a means~(206)Pb/~(238)U age of 92.9±1.9Ma(N=10,MSWD=0.71),and zircon derived from a granitie-porphyry outcrop at the Tongjie section yielded a means~(206)Pb/~(238)U age of 86.9±1.4Ma(N=9,MSWD=3.70),both obtained using the SHRIMP U-Pb method.These ages suggest that the tin(copper)mineralization in the Dulong Sn-Zn deposit was mainly related to the late Cretaceous magmatic hydrothermal events.The geochronological data of the Gejiu(Sn)and the Bainiuchang (Ag)super-large deposits and related Yanshanian granites indicate that there was a large-scale granitic magmatism and mineralization event during the Cretaceous in southeastern Yunnan,which might have been related to the lithospheric extension of the South China Block in late Mesozoic.