Reassessment of petrogenesis of Carboniferous-Early Permian rift-related volcanic rocks in the Chinese Tianshan and its neighboring areas

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• 作者：Linqi Xia ; ^{geologyx@pub.xaonline.com} ; Xueyi Xu ; Xiangmin Li ; Zhongping Ma ; Zuchun Xia
• 关键词：Carboniferous&ndash ; Early Permian rift-related volcanism ; Tianshan&ndash ; Tarim (central Asia) large igneous province ; Asthenosphere ; Mantle plume ; Lithosphere contamination
• 刊名：Geoscience Frontiers
• 出版年：2012
• 期刊代码：pc98_16749871
• 类别：ear
• 出版时间：July, 2012
• 卷：3
• 期：4
• 页码：445-471
• 文件大小：6236 K

摘要

The Carboniferous鈭扙arly 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 (360-351 Ma) 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 鈭?52 Ma and A-type granite with age of 鈭?58 Ma 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 鈥渙re-bearing鈥?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.