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宁芜北段与梅山铁多金属矿床有关的辉长闪长玢岩的LA-MC-ICP-MS锆石U-Pb定年:对岩浆热液成矿系统时限的约束
引用本文:车林睿,余金杰 王铁柱 陆邦成 王贤伟.宁芜北段与梅山铁多金属矿床有关的辉长闪长玢岩的LA-MC-ICP-MS锆石U-Pb定年:对岩浆热液成矿系统时限的约束[J].中国地质,2014,41(6):1805-1820.
作者姓名:车林睿  余金杰 王铁柱 陆邦成 王贤伟
作者单位:中国地质科学院矿产资源研究所;国土资源部成矿作用与资源评价重点实验室;中国地质大学地球科学与资源学院;
基金项目:国家自然科学基金项目(41372091);国家重点基础研究发展计划“973计划”(2012CB416803)联合资助
摘    要:梅山铁多金属矿床是宁芜盆地内代表性矿床之一,其Fe-Cu-Au-Mo矿化与辉长闪长玢岩密切相关。本文对含矿辉长闪长玢岩及矿体下部的新鲜辉长闪长玢岩进行LA-MC-ICP-MS锆石U-Pb定年,获得年龄分别为(137.8±1.7)Ma、(141.2±1.0)Ma。因此辉长闪长玢岩形成时间应在138~141 Ma,伴随的Fe-Cu-Au-Mo矿化稍晚,都属于早白垩世,受区域岩石圈伸展和减薄作用制约。根据年代学和地质事实证据,初步认为宁芜盆地早白垩世火山活动从北段开始,火山活动持续时间至少为7~10 Ma。辉长闪长玢岩中古老锆石年龄变化于1898~1903 Ma、1163 Ma和292~296 Ma,时代分别为古元古代、新元古代和早二叠纪,暗示着岩浆上侵过程中基底岩石对岩浆可能有混染作用,表明长江中下游成矿带存在早元古代结晶基底和中—晚元古代褶皱基底的"双层结构"。

关 键 词:锆石U-Pb年龄  辉长闪长玢岩  古老锆石  梅山铁多金属矿床  宁芜北段

LA-MC-ICP-MS U-Pb dating of zircons from gabbro-diorite porphyry related to the Meishan polymetallic iron deposit in northern Ningwu Basin: Constraints on the age of the magmatic-hydrothermal metallogenic system
CHE Lin-rui,YU Jin-jie,WANG Tie-zhu,LU Bang-cheng,WANG Xian-wei.LA-MC-ICP-MS U-Pb dating of zircons from gabbro-diorite porphyry related to the Meishan polymetallic iron deposit in northern Ningwu Basin: Constraints on the age of the magmatic-hydrothermal metallogenic system[J].Chinese Geology,2014,41(6):1805-1820.
Authors:CHE Lin-rui  YU Jin-jie  WANG Tie-zhu  LU Bang-cheng  WANG Xian-wei
Abstract:Abstract: The Meishan polymetallic iron deposit is one of the representative deposits in Ningwu Basin, with its Fe-Cu-Au-Mo mineralization related closely with the gabbro-diorite porphyry. In this paper, the authors conducted LA-MC-ICP-MS zircon U-Pb dating of the ore-bearing gabbro-diorite porphyry and the fresh gabbro-diorite porphyry under the orebody, and obtained the U?Pb ages of (137.8±1.7) Ma and (141.2±1.0) Ma, respectively, suggesting that the gabbro-diorite porphyry was formed in 138~141Ma, the accompanying Fe-Cu-Au-Mo mineralization might have taken place later, and both occurred in Early Cretaceous, constrained by a tectonic regime extension and lithospheric thinning environment. Depending on the chronology and geological facts evidence, the authors put forward a new viewpoint that the volcanic-magmatism of Ningwu Basin began from the north and lasted for 7~10 Ma at least. The U-Pb ages of the older zircons from the gabbro-diorite porphyry range from 1903 to 1898 Ma, 1163 Ma and 296 to 292 Ma, suggesting Paleoproterozoic, Neoproterozoic and Early Permian. These data imply that the basement rocks made some contribution to the magmatism and there existed the so-called double layer structure of the Paleoproterozoic crystalline basement plus the Mesoproterozoic-Neoproterozoic fold basement in the Middle-Lower Yangtze River valley metallogenic belt (YRB).
Keywords:zircon U-Pb dating  gabbro-diorite porphyry  Meishan  older zircons  northern Ningwu Basin
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