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内蒙古边家大院铅锌银矿床位于大兴安岭成矿带南段,是一个典型的热液脉型多金属矿床。为了精确厘定该矿床的成岩时代,对区内与成矿关系密切的辉长岩体及闪长岩岩脉中的锆石进行了LA-ICP-MS U-Pb定年,获得辉长岩与闪长岩样品的形成年龄分别为133±0.86 Ma和130±0.75 Ma,表明岩体为早白垩世岩浆活动的产物。岩石化学研究表明,辉长岩与闪长岩具有低钛高钾、稀土元素分配模式为轻稀土富集型、大离子亲石元素(LILE)富集明显、高场强元素(HFSE)相对亏损的特征,推断岩浆来源于岩石圈地幔,形成于张性环境。结合矿床地质特征及前人在区域上的研究成果,认为燕山期是大兴安岭南段成矿和成岩高峰期之一,矿区侵入岩可能形成于由全面挤压向伸展过渡阶段的构造背景。
Located in the southern section of the Daxinganling metallogenic belt, the border house of Inner Mongolia, Yunnan Province, is a typical hydrothermal vein type polymetallic deposit. In order to accurately determine the age of diagenesis in this deposit, LA-ICP-MS U-Pb dating of gabbro and diorite diorites, which are closely related to metallogenesis, has been carried out to obtain gabbro and flash The formation ages of the long rock samples are 133 ± 0.86 Ma and 130 ± 0.75 Ma, respectively, indicating that the rock mass is the product of the Early Cretaceous magmatism. Petrochemical studies show that gabbro and diorite have low Ti and K contents, LREE patterns are LREE enrichment, LILE enrichment is obvious, and HFSE is relatively depleted It is inferred that magma originated from the lithospheric mantle and formed in a tension environment. Based on the geological characteristics of the deposit and the predecessors’ research results in the region, Yanshanian is considered to be one of the mineralization and diagenetic peak periods in the southern section of the Greater Hinggan Mountains. The intrusive rocks in the mining area may form in the tectonic setting during the transition from a complete compression to extension.