Reassessment of petrogenesis of Carboniferous–Early Permian rift-related volcanic rocks in the Chinese Tianshan and its neighboring areas
Reassessment of petrogenesis of Carboniferous–Early Permian rift-related volcanic rocks in the Chinese Tianshan and its neighboring areas
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DOI：
10.1016/j.gsf.2011.12.011
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发表时间：
2012-07
影响因子：
8.9
通讯作者：
Linqi Xia;Xueyi Xu;Xiangmin Li;Zhongping Ma;Zuchun Xia
中科院分区：
文献类型：
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作者：
Linqi Xia;Xueyi Xu;Xiangmin Li;Zhongping Ma;Zuchun Xia
石炭纪—早二叠世与裂谷相关的火山序列覆盖了中国天山及其邻区的大面积区域，构成了世界上新认识的重要的显生宙大型火成岩省，可进一步分为天山和塔里木两个子省。下石炭统基底或前石炭统岩石的区域性不整合面、最年轻蛇绿岩的年龄（360~351Ma）、高压低温变质带俯冲变质作用的峰值以及~352Ma的含镍铜镁铁质-超镁铁质侵入岩和~358Ma的A型花岗岩的出现，揭示了古亚洲洋的最终闭合。可能发生在密西西比早期。我们的总结表明，这个大型火成岩省至少满足通常用于识别古代软流圈上升流（或地幔柱）的四个标准：（1）岩浆作用之前的地表隆起； （二）与大陆裂谷、裂解事件有关的； (3) 软流圈（或羽流）衍生玄武岩的化学特征； (4) 与大规模矿化和未受污染的玄武岩密切相关，类似于许多“含矿”大型火成岩省，在羽流和 EM1 地球化学特征之间显示出 Sr-Nd 同位素变化。这些表明石炭纪软流圈上升流和早二叠世羽流在天山-塔里木（中亚）大型火成岩省的形成中发挥了核心作用。
The Carboniferous−Early Permian rift-related volcanic successions, covering large areas in the Chinese Tianshan and its adjacent areas, make up a newly recognized important Phanerozoic large igneous province in the world, which can be further divided into two sub-provinces: Tianshan and Tarim. The regional unconformity of Lower Carboniferous upon basement or pre-Carboniferous rocks, the ages (360–351Ma) of the youngest ophiolite and the peak of subduction metamorphism of high pressure–low temperature metamorphic belt and the occurrence of Ni-Cu-bearing mafic-ultramafic intrusion with age of ∼352Ma and A-type granite with age of ∼358Ma reveal that the final closure of the Paleo-Asian Ocean might take place in the Early Mississippian. Our summation shows that at least four criteria, being normally used to identify ancient asthenosphere upwelling (or mantle plumes), are met for this large igneous province: (1) surface uplift prior to magmatism; (2) being associated with continental rifting and breakup events; (3) chemical characteristics of asthenosphere (or plume) derived basalts; (4) close links to large-scale mineralization and the uncontaminated basalts, being analogous to those of many “ore-bearing” large igneous provinces, display Sr-Nd isotopic variations between plume and EM1 geochemical signatures. These suggest that a Carboniferous asthenosphere upwelling and an Early Permian plume played the central role in the generation of the Tianshan–Tarim (central Asia) large igneous province.