The Early Jurassic Fe-Sn metallogenic event and its geodynamic setting in South China: Evidence from Re-Os, U-Pb geochronology and geochemistry of the Dading magnesian skarn Fe-Sn deposit
The Early Jurassic Fe-Sn metallogenic event and its geodynamic setting in South China: Evidence from Re-Os, U-Pb geochronology and geochemistry of the Dading magnesian skarn Fe-Sn deposit
复制标题
华南早侏罗世铁锡成矿事件及其地球动力学背景——来自大定镁砂岩铁锡矿床Re-Os、U-Pb年代学和地球化学的证据
DOI：
10.1016/j.oregeorev.2019.102970
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发表时间：
2019
影响因子：
3.3
通讯作者：
Mao Jingwen
中科院分区：
文献类型：
--
作者：
Zhao Panlao;Zhao Haijie;Yuan Shunda;Mao Jingwen
华南陆块是世界上最大的钨锡多金属成矿区之一，绝大多数矿床形成于中生代。早侏罗世华南板块是一个岩浆和成矿作用的平静期，是古特提斯向古太平洋动力学域转换的响应。大顶铁锡存款矿床是华南地区罕见的早侏罗世存款矿床。西姆斯锆石U-Pb和辉长岩Re-Os定年结果表明，大顶铁锡存款（185.9 ± 4.9 Ma）和与之相关的石碑花岗岩（189.0 ± 1.5 Ma）形成于早侏罗世，为华南造山带早侏罗世铁锡成矿事件提供了有力的证据。岩石地球化学特征表明，石背花岗岩具有高SiO2、Nb、Zr + Nb + Ce + Y含量和高Ga/Al比值，而低Y/Nb比值，与A1型花岗岩相似。锆石εHf（t）值变化范围大（-2.4至+3.4）、锆石εHf（t）与δ 18 O值之间的负相关性以及独特的全岩Sr-Nd同位素组成（εNd（t）=-3.3至-3.7; ISr= 0.7063 - 0.7085），表明石北花岗岩可能来自先存地壳和年轻物质的混合物源，其中OIB-比如同位素组成结合火山-侵入岩、沉积盆地和构造变形样式的空间展布，认为早侏罗世铁锡成矿作用发生在拉张环境中，可能与华南板块和印支地块之间印支期造山带的后造山塌陷有关。
The South China Block (SCB) is one of the largest W-Sn-polymetallic metallogenic district over the world, with most of the deposits formed during the Mesozoic. The Early Jurassic of SCB was considered as a magmatic and metallogenic quiescence stage, as response to the tectonic transition from the paleo-Tethyan to the paleo-Pacific geodynamic domains. The Dading Fe-Sn deposit is a quite rare Early Jurassic deposit recognized in SCB. SIMS Zircon U–Pb and molybdenite Re-Os dating indicate that the Dading Fe–Sn deposit (185.9 ± 4.9 Ma) and related Shibei granite (189.0 ± 1.5 Ma) formed at the Early Jurassic, which provides convincing evidence for a previously unrecognized Early Jurassic Fe–Sn metallogenic event in SCB. Geochemical data show that the Shibei granite has high SiO2, Nb, Zr + Nb + Ce + Y concentrations and high Ga/Al ratio, but low Y/Nb ratio, which are similar to those of A1-type granite. The large range of zircon εHf(t) values (−2.4 to +3.4), negative correlation between zircon εHf(t) and δ18O values, and unique whole-rock Sr–Nd isotopic compositions (εNd(t) = −3.3 to −3.7;ISr= 0.7063 – 0.7085) suggest that the Shibei granite is likely to originate from a mixed source of pre-existing crust and juvenile material with OIB-like isotopic composition. Combining with the spatial distribution of the volcanic–intrusive rocks, sedimentary basins, and tectonic deformation styles, we suggest that the Early Jurassic Fe–Sn mineralization occurred in an extensional environment, which was probably linked to the post-orogenic collapse of the Indosinian orogeny between the SCB and Indochina Block.