Zhang, Zuoheng, Chai, Fengmei, Wang, Tuanhua, Cheng, Yanbo, Xu, Lingang, and Yuan, Shunda (2012) Geochronology, geochemistry and petrogenesis of diabase dyke swarms in East Tianshan, Xinjiang, NW China. Acta Geologica Sinica, 86 (6). pp. 1500-1514.

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Abstract

Diabase dyke swarms are widespread in the East Tianshan and Beishan regions. LA-ICP-MS zircon U-Pb ages of these diabase vary from 305 Ma to 278 Ma, showing that these dykes were formed during Late Carboniferous-Early Permian magmatism. All diabase samples are subalkali calc-alkali, characterized by slight LREE and LILEs enrichment, and weak negative Ti, Nb and Ta anomalies. The diabase samples have positive ε(Nd)(t) values (>+3), high Sr isotopic compositions (initial 87Sr/86Sr values=0.7030–0.7097), and large variation of Pb isotopic compositions, indicating they were derived from a deplete mantle source. Regional geology and geochemistry evidences indicate that these diabase dyke swarms were generated in a lithosphere extensional setting and had the same magma sources. Initial magmas may be a mixture of depleted asthenosphere mantle and enriched lithospheric mantle during rapid magma ascending.

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