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Geochemistry of Metamafic Dykes from the Quanji Massif: Petrogenesis and Further Evidence for Oceanic Subduction, Late Paleoproterozoic, NW China 被引量:3
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作者 Hassan Abdelslam Mustafa Qinyan Wang +3 位作者 Nengsong Chen Fanxi Liao Min Sun Meshaal Abdelgadir Salih 《Journal of Earth Science》 SCIE CAS CSCD 2016年第4期529-544,共16页
A suite of ~1.84-1.92 Ga metamafic dykes within the paragneiss suite(khondalite) of the Quanji massif in NW China, has been chosen in this study for further understanding the tectonic evolution and possible links to... A suite of ~1.84-1.92 Ga metamafic dykes within the paragneiss suite(khondalite) of the Quanji massif in NW China, has been chosen in this study for further understanding the tectonic evolution and possible links to the global Columbia supercontinent. Occurrence and field relations suggest that they were formed coevally with a previous studied ~1.83-1.85 Ga metamafic dyke swarms. Whole-rock major and trace elemental geochemistry suggests precursor magma of the amphibolites being generated from a volcanic arc-related tectonic setting rather than a back-arc environment where the metamafic dyke swarms were emplaced. The metamafic dykes show enrichment of LREE and strongly negative anomalies for Ta-Nb, Zr-Hf and Ti, have high SiO_2(49.3 wt.%-52.5 wt.%) but low MgO(6.40 wt.%-7.76 wt.%) contents and Mg~#(Mg~#=[100×(MgO/40.3)]/[MgO/40.3+FeO/71.8]) values(45.7-52.1), suggesting evolved precursor magma. The high values of La/Ta(22.2-42.8) and La/Nb(1.71-2.47), mildly negative εNd(t) values(-2.51-0.15), with depleted mantle model ages(TDM) of 2.45-2.84 Ga, suggest that their precursor magmas were possibly derived from a subduction-related fluid metasomatized Archean sub-continental lithospheric mantle. This study provides further evidence for oceanic plate subduction prevailing before or around ~1.85 Ga, which confirms a prolonged subduction-accretion-collision history in the NW China which is possibly linked to the assembly of the Columbia supercontinent. 展开更多
关键词 metamafic dyke GEOCHEMISTRY PETROGENESIS tectonic setting Quanji massif NW China.
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Zircon U-Pb Age,Geochemical Data:Constraints on the Origin and Tectonic Evolution of the Metamafic Rocks from Longmuco-Shuanghu-Lancang Suture Zone,Tibet 被引量:7
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作者 Yanwang Wu Cai Li +2 位作者 Mengjing Xu Chaoming Xie Ming Wang 《Journal of Earth Science》 SCIE CAS CSCD 2017年第3期422-432,共11页
Bulk-rock major and trace elements and zircon U-Pb data are reported for Permian metamafic rocks from Guoganjianan, in the western part of Longmuco-Shuanghu-Lancang suture zone. These results offer new insights into m... Bulk-rock major and trace elements and zircon U-Pb data are reported for Permian metamafic rocks from Guoganjianan, in the western part of Longmuco-Shuanghu-Lancang suture zone. These results offer new insights into mantle source characteristics and geodynamic setting of Permian ophiolitic fragments. U-Pb isotopic dating using SHRIMP II method reveals that the metamafic rocks were formed at 274.7± 3.9 and 279.8± 3.6 Ma. The metamafic rocks mostly show N-MORB-typed rare earth element patterns and are enrichment in large-ion lithophile elements, indicating that they are probably derived from partial melting of a depleted mantle in a back-arc basin. Our new data, together with recent studied results on Paleozoic ophiolitic fragments suggest the Paleo-Tethys Ocean in Central Qiangtang opened at Cambrian and widened between Ordovician and Devonian. Northward subduction started in the Late Devonian–Early Carboniferous and a back-arc basin developed during Permian. 展开更多
关键词 Tibet Longmuco-Shuanghu-Lancang suture zone metamafic rock zircon SHRIMP U-Pb dating geochemistry
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