东昆仑造山带低山头花岗岩体岩石地球化学特征及其地质意义  

Petro-Geochemical Characteristics and Geological Significance of Dishantou Granite Body in East Kunlun Orogenic Belt

作　　者：邓红宾 李培龙 魏华财 何文劲 杨鹏涛[1] 李宁[1] 唐华[1] Deng Hongbin;Li Peilong;Wei Huacai;He Wenjin;Yang Pengtao;Li Ning;Tang Hua(Sichuan Northwest Geological Team,Bureau of Exploration and Exploitationof Geology and Mineral Resources of Sichuan Province,Mianyang 621000,Sichuan,China)

机构地区：[1]四川省地质矿产勘查开发局川西北地质队,四川绵阳621000

出　　处：《吉林大学学报（地球科学版）》2021年第3期767-782,共16页Journal of Jilin University：Earth Science Edition

基　　金：中国地质调查局项目(12120114000201);青海省自然资源厅地质勘查基金项目(青地调勘[2017]247号)。

摘　　要：低山头一带花岗岩体归属东昆仑弧盆系北昆仑岩浆弧带,位于东昆仑成矿带伯喀里克—香日德成矿亚带东昆仑造山带中段,岩石类型主要为石英闪长岩、正长花岗岩及二长花岗岩。为了加强该地区花岗岩体岩石地球化学与成岩成矿背景探讨,对花岗岩体开展了主量元素、微量元素及矿质元素研究。主量元素组成上,石英闪长岩具中硅(57.64%和58.47%)、富钠(Na2O/K2O均为2.57)特点,正长花岗岩具高硅(75.45%-75.99%)、富钾(Na2O/K2O为0.74-0.94)特点,二长花岗岩具高硅(66.80%-73.45%)、富钠(Na2O/K2O为1.50-2.13)特点;花岗岩体铝饱和指数A/CNK<1,为准铝质岩浆岩;碱饱和指数NK/A集中在0.26-0.69之间,属钙碱性岩石;里特曼组合指数σ43在1.18-2.31之间,属钙碱性类型。花岗岩体轻稀土元素相对重稀土元素富集,岩浆分异特征明显,大离子亲石元素(LILE)富集Rb、K、Ba、Th、Sr、Nd,仅正长花岗岩Sr亏损,高场强元素(HFSE)富集Zr、Hf、Ce,而Nb、P、Ti明显亏损,源区物质为壳幔混合物质,属挤压应力环境中同碰撞I型花岗岩。在岩体实测剖面中获得11种元素分析数据,与青海全省、东昆仑成矿带及其亚成矿带平均元素丰度值进行对比,初步划分不同岩性、不同类型、不同时代花岗岩,以及富集的含矿元素为Au、Zn、Y、Pb等。与区域有成矿事实且为I型花岗岩成因进行对比,认为研究区有较好的找矿前景。The granite body in Dishantou area belongs to the North Kunlun magmatic arc belt of the East Kunlun arc basin. It is located in the middle part of the East Kunlun orogenic belt in the Berkarik Xiangride metallogenic sub belt of the East Kunlun metallogenic belt. The main rock types are quartz diorite, syenogranite and monzogranite. To strengthen the study on the petro-geochemistry and diagenesis and metallogenic background of the granitic bodies in this area, the analysis on the major elements, trace elements, and mineral elements of the granitic bodies has been carried out. The quartz diorite has the characteristics of medium silicon(57.64% and 58.47%) and rich sodium(Na2O/K2O is 2.57) in the composition of the main elements. The syenogranite is characterized by high silicon(75.45%-75.99%) and rich potassium(Na2O/K2O is 0.74-0.94). The monzogranite is characterized by high silicon(66.80%-73.45%) and rich sodium(Na2O/K2O is 1.50-2.13). A/CNK of the granitic body is less than 1, indicating that it is aluminous magmatic rock. The alkali saturation index(NK/A) ranges from 0.26 to 0.69, belonging to calc-alkaline type. The light rare earth elements are relatively enriched in heavy rare earth elements(characteristics of magmatic differentiation), large ion lithophile elements(LILE) of Rb, K, Ba, Th, Sr and Nd, only syenogranite is depleted in Sr;Meanwhile, high field strength elements(HFSE) are rich in Zr, Hf and Ce, but Nb, P, and Ti are depleted apparently, indicating the source materials of crust-mantle mixing, formed under an extrusion stress environment with collision type I granite. In 11 kinds of elements analysis of data obtained from the rock mass, compared with the average element abundances of Qinghai Province, the East Kunlun metallogenic belt and its sub metallogenic belt, the granite types with different lithology and different ages are preliminarily divided, and the enriched ore-bearing elements are Au, Zn, Y, Pb, etc. Compared with the regional metallogenic facts and the genesis of I-type granites, the

关 键 词：岩石成因 花岗岩体 地球化学 矿质元素 东昆仑造山带 低山头一带 

分 类 号：P581[天文地球—岩石学]