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Xingtai, China

Sun Y.,Wuhan University | Xiao L.,Wuhan University | Zhu D.,Wuhan University | Wu T.,Wuhan University | And 3 more authors.
Ore Geology Reviews | Year: 2014

The Qicun intrusive complex is one of the major ore-related intrusions in the Handan-Xingtai district, eastern North China Craton. It consists of four intrusive bodies dominated by monzonite, quartz monzonitic diorite, quartz monzonite, and biotite diorite, respectively. The biotite diorite has a LA-ICP-MS zircon U-Pb age of 128.9±0.93Ma, indicating its emplacement in the early Cretaceous when the North China Craton was extensively reactivated. Rocks of the Qicun complex have high MgO (1.69-9.50wt.%), high LaN/YbN (5.32-17.59) and Sr/Y (18.05-101.10) ratios, with low Y (8.17-20.43ppm) and Yb (0.86-1.85ppm) contents. They are enriched in light rare earth elements (LREE) but depleted in heavy rare earth elements (HREE) and high field strength elements (HFSE) with weak or no positive Eu anomalies, features assembling adakites. In addition, whole-rock samples have initial 87Sr/86Sr ratios ranging from 0.70663 to 0.70767 and εNd(t=130Ma) between -16.5 and -14.3, which are consistent with zircon 176Hf/177Hf ratios of 0.281739 to 0.282083 and εHf(t) values of -33.8 to -21.7. The isotopic signatures, when combined with existing geological and geochemical data, indicate that the Qicun complex, and by inference other contemporaneous intrusions in the Handan-Xingtai district, formed by mixing of mantle-derived magmas with partial melts of delaminated lower continental crust under a lithospheric extensional setting related to the destruction of the North China Craton. Widespread presence of inherited zircon grains of ca. 2.5-2.4Ga in the intrusions is consistent with a contribution of delaminated lower crust in the formation of the Qicun complex. © 2013.

Sun Y.,Wuhan University | Xiao L.,Wuhan University | Zhan Q.,Wuhan University | Wu J.,Wuhan University | And 4 more authors.
Journal of Asian Earth Sciences | Year: 2015

The Handan-Xingtai district in eastern China exposes numerous late Mesozoic intrusions. Among these, the Kuangshancun intrusive complex is one of the major ore-related intrusions whereas the Hongshan complex is barren, although both intrusions display similar geochemical characteristics. The Kuangshancun complex consists of diorite and monzonite, with zircon LA-ICP-MS U-Pb age of 133.7±1Ma. The Hongshan complex mainly consists of syenite and shows zircon U-Pb age of 134.5±1Ma. The mineral chemistry of plagioclase from both complexes reveals normal zoning, consistent with the fractional crystallization process. Rocks of the Kuangshancun complex show SiO2 in the range of 58.92-63.84wt.%, Na2O of 4.63-8.81wt.%, and Al2O3 of 16.14-18.18wt.%, together high Sr/Y (14-54) and high LaN/YbN (8.30-16.18) ratios. They show enrichment in LREE and depletion in HREE and HFSE, with no remarkable Eu anomalies, similar to the features of adakites. The whole rock initial 87Sr/86Sr ratios range from 0.706661 to 0.706722 and ε Nd (t =134Ma) between -15.26 and -15.12, which are consistent with zircon 176Hf/177Hf ratios of 0.281940-0.282059 and ε Hf (t) values of -27.0 to -22.7. Samples of the Hongshan complex show SiO2 in the range of 56.57-68.16wt.%, high Sr/Y (19-112) and high LaN/YbN (11.39-16.82) ratios. The zircon ε Hf (t) values are in the range of -15.9 to -12.8 and ε Nd (t =134Ma) is between -9.82 and -8.62. The Kuangshancun complex was derived through partial melting of an enriched lithospheric mantle contaminated by lower continental crust components. The Hongshan complex was also derived from the EM I-like mantle source. However, the calculated zircon Ce4+/Ce3+ and Eu/Eu* ratios indicate that the source magma of the Kuangshancun complex were characterized by higher oxygen fugacity as compared to that the Hongshan complex. The high oxidation states and high water contents are considered as possible key factors that led to the iron mineralization in the Kuangshancun and other intrusions in the Handan-Xingtai district. © 2015.

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