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Chronology and Pb isotope compositions of Early Cretaceous adakitic rocks in Xuzhou-Huaibei area,central China:Constraints on magma sources and tectonic evolution in the eastern North China Craton

2008; Science Press; Linguagem: Inglês

2095-8927

Yang De, Pei Fu,

Geological and Geophysical Studies

This paper reports Pb isotopic compositions of the Early Cretaceous adakitic rocks in the Xuzhou-Huaibei area and LA- ICP-MS zircon U-Pb dating results and discusses the nature of magma sources and the Mesozoic tectonic evolution in the eastern North China Craton.The dating results indicate that the Banjing,Fengshan and Caishan intrusions formed in the Early Cretaceous,i.e., their weighted mean ~(206)Pb/~(238)U ages being 127±1Ma,129±2Ma,and 131±1Ma,respectively.Whole-rock initial (~(206)pb/~(204)pb)_t, (~(207)pb/~(204)pb)_t and (~(208)Pb/~(204)Pb)_t ratios from five intrusions,including Liguo,Banjing,Jiagou,Fengshan and Caishan,range from 17.957 to 18.620,15.508 to 15.655 and 38.129 to 38.710,respectively.Combined with chronology of inherited and captured zircons in the host rocks and eclogite xenoliths,it is suggested that the Early Cretaceous adakitic magmas could be mainly derived from partial melting of the Yangtze Craton basement and minor the North China Craton basement,which is consistent with subduction of the Yangtze Craton beneath the North China Craton oriented in NW direction in the Early Mesozoic.