内蒙古浩布高铅锌矿床小罕山岩体年代学、Hf同位素及地球化学特征

内蒙古赤峰浩布高铅锌矿床大地构造位置位于大兴安岭地区南段,属黄岗梁—甘珠尔庙褶皱成矿带.对浩布高铅锌矿床小罕山岩体进行了详细的岩石学、年代学、岩石地球化学和Hf同位素研究.结果显示:小罕山岩体主要岩石类型为二长花岗岩,形成于(143.9±1.1)Ma,属于早白垩世;地球化学组成上表现出高硅(SiO2=66.96％ ～6...

Zircon U-Pb Geochronology,Hf isotope and Whole-Rock Geochemical Characteristics of Xiaohanshan Pluton in Haobugao Pb-Zn Deposit,Inner Mongolia

The Haobugao lead-zinc deposit is tectonically located in the southern part of the Great Xing’an Range, and is part of the Huanggangliang-Ganzhuermiao tectono-metallogenic belt. In this paper, detailed data on petrology, U-Pb geochronology, geochemistry and Hf isotopes were presented on the Xiaohanshan pluton of the Haobugao lead-zinc deposit. The results show that the main rock type of the Xiaohanshan pluton is monzogranite, which was formed in the Early Cretaceous (143.9±1.1 Ma). The rocks have high SiO₂ (66.96%-68.05%) and alkali (Na₂O+K₂O=9.91%-10.09%), but low Al₂O₃ (15.69%-16.49%), CaO (1.22%-1.41%), and TFe₂O₃/MgO (average 8.29). The rocks belong to metaluminous to peraluminous granites with right-inclining REE distribution patterns and distinct negative Eu anomalies (0.33-0.41). The samples also show enrichments in large ion lithophilic elements (LILEs, e.g., Rb, K) and other incompatible elements (e.g., Th, U), whereas high field strength elements (HFSEs, e.g., Nb, P, Nb, Ta, Ti) are depleted, showing A2-type granite affinity. The rocks have initial ¹⁷⁶Hf/¹⁷⁷Hf values of 0.282,829-0.282,936(average 0.282,888) and ε_Hf(t) of 4.4 to 8.4 (average 6.7), indicating that the Xiaohanshan pluton is mainly derived from partial melting of the middle and lower crust with minor mantle material input. It is considered that formation of the Xiaohanshan pluton was related to the post-collision extensional tectonics in the Early Cretaceous Paleo-Pacific subduction continental margin.