青海南山构造带西段黑马河花岗杂岩体锆石U-Pb年代学、地球化学特征及其地质意义

发布时间：2018-06-02 09:49

本文选题：青海南山 + 黑马河花岗杂岩体　；参考：《地质论评》2017年04期

【摘要】：本文对青海南山构造带西段黑马河花岗杂岩体中的石英闪长岩和花岗闪长岩以及花岗闪长岩中的暗色微粒包体进行了详细的岩石学、岩石地球化学和LA-ICP-MS锆石U-Pb年代学研究。结果表明,花岗闪长岩及暗色微粒包体的结晶年龄分别为244.4±1.1 Ma和243.0±1.2 Ma,表明岩体形成于中三叠世早期。石英闪长岩和花岗闪长岩为准铝质高钾钙碱性系列,暗色微粒包体为高钾钙碱性—钾玄岩系列,稀土元素配分曲线均具有轻重稀土明显分异的右倾特征,具弱负Eu异常(δEu=0.65~0.83),富集大离子亲石元素(Cs、Rb、Th、K)和Pb,亏损高场强元素(Nb、Ta、Ti)和P、Ba负异常。岩相学和岩石地球化学特征指示黑马河花岗杂岩体具壳幔岩浆混合特征,形成于活动大陆边缘的俯冲环境,石英闪长岩为受俯冲流体交代的地幔楔部分熔融产生的基性岩浆演化的产物,花岗闪长岩则源自壳源岩浆与少量幔源岩浆的混合。黑马河花岗杂岩体是中三叠世早期宗务隆洋向南俯冲消减的岩浆记录。
[Abstract]:In this paper, the detailed petrology, geochemistry and LA-ICP-MS zircon U-Pb chronology of quartz diorite and granodiorite in the Haimahe granitic complex in the western part of the Nanshan tectonic belt, Qinghai Province, as well as the dark color particle inclusions in the granodiorite are studied in detail. The results show that the crystallization ages of granodiorite and dark particle inclusions are 244.4 卤1.1 Ma and 243.0 卤1.2 Ma, respectively, indicating that the granodiorite was formed in the early Middle Triassic. Quartz diorite and granodiorite are quasi-aluminous high-potassium calc-alkaline series, dark particle inclusions belong to high-potassium calc-alkaline potash series, and the REE distribution curves have the characteristics of right deviation of light and heavy rare earth elements. There are weak negative EU anomalies (未 EU ~ (0.65) ~ (0.65) ~ (0.83), enrichment of large ion lipophilic elements (CsN, Rb ~ (+) and Pb, and depletion of high field strength elements, such as NB ~ (2 +) ~ (2 +) ~ (2 +) and Ba. The petrographic and petrogeochemical characteristics indicate that the Haimahe granitic complex is characterized by the mixing of crust and mantle magma, and formed in the subduction environment of the active continental margin. Quartz diorite is the product of basic magma evolution caused by partial melting of mantle wedge metasomatized by subduction fluid, while granodiorite is derived from the mixing of crust-derived magma and a small amount of mantle-derived magma. The Heimahe granitic complex is a magmatic record of subduction of the Zongwu uplift ocean in the early Middle Triassic.
【作者单位】：西部矿产资源与地质工程教育部重点实验室国土资源部岩浆作用成矿与找矿重点实验室长安大学地球科学与资源学院;山东理工大学资源与环境工程学院;中国地质大学(
【基金】：国家自然科学基金资助项目(编号:41472191、41502191、41172186) 中国地质调查局地质调查项目(编号:12120114041201、12120114018219) 中央高校基本科研业务费专项资金项目(编号:CHD2011TD020、2013G1271091、2013G1271092)的成果~~
【分类号】：P587;P597.3

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