东昆仑祁漫塔格虎头崖铅锌多金属矿区花岗岩年代学、地球化学及Hf同位素特征  

Geochronology,geochemical characteristics and Hf isotopic compositions of granite in the Hutouya deposit,Qimantag,East Kunlun

作　　者：李侃[1] 高永宝[1] 钱兵[1] 何书跃 刘永乐 张照伟[1] 张江伟[1] 王亚磊[1] 

机构地区：[1]中国地质调查局西安地质调查中心国土资源部岩浆作用成矿与找矿重点实验室,陕西西安710054 [2]青海省第三地质矿产勘查院,青海西宁810029

出　　处：《中国地质》2015年第3期630-645,共16页Geology in China

基　　金：中国地质调查局地质调查项目(1212011121088;1212011121092和12120114044401);国家自然科学基金青年基金项目(41102050);国家"十一.五"科技支撑计划项目(2006BAB01A01);陕西省科学技术研究发展计划项目(2015KJXX-71);陕西省自然科学基础研究计划项目(2013JM5010);中国地质调查局青年地质英才计划(2013)联合资助

摘　　要：虎头崖铅锌多金属矿床位于东昆仑祁漫塔格地区,矿区内中酸性侵入岩体广泛发育,且与成矿关系密切。LA-ICP-MS锆石U-Pb同位素年龄测试表明,虎头崖Ⅴ矿带外围花岗闪长岩形成时代为（224.3±0.6）Ma,Ⅷ号矿带矿体下部正长花岗岩形成时代为（239.7±0.8）Ma,岩体形成时代为中—晚三叠世。岩石地球化学表明,花岗闪长岩富钾贫钠（K2O/Na2O为2.02~2.88）,无明显负Eu异常（δEu为0.68~1.06）,富集Rb、Th、U、K等大离子亲石元素,明显亏损Nb、P、Ti等元素,属I型花岗岩;正长花岗岩具高硅、富碱、低铁镁、贫钙磷钛的特征,负Eu强烈（δEu为0.08~0.26）,富集Rb、Th、U、K,亏损P、Ti、Ba、Sr,属高分异I型花岗岩;二者均形成于后碰撞构造背景;Hf同位素组成不均一,指示其经历了壳幔岩浆混合作用,幔源物质的加入可能带来了丰富的成矿物质。The Hutouya Pb- Zn polymetallic ore deposit is located in Qimantag, East Kunlun. Intermediate- acid intrusive rocks occur widely in this area, and are closely related to iron polymetallic mineralization. The results of LA- ICP- MS zircon U- Pb isotope dating reval that the granodiorite in the periphery of No. Ⅴore belt was formed at（224.3±0.6） Ma and the orthoclase granitein No. Ⅷ ore belt was formed at（239.7±0.8） Ma. Petrogeochemistry shows that the granodiorite is rich in K and poor in Na, with no strong negative Eu anomalies（δEu=0.68-1.06）, and is enriched in Rb, Th, U, K, but depleted in Nb, P, Ti, thus belonging probably to I- type granite series. The orthoclase granite is characterized by high Si O2, high alkali, low TFe O, Mg O, Ca O, P2O5 and Ti O2,strong negative Eu anomalies（δEu 0.08- 0.26）, enrichment of Rb, Th, U, K,and depletion of P, Ti, Ba, Sr, belonging probably to highly fractionated I-type granite series. Both of them were formed at the post-collision stage. Variable Hf isotopic compositions of zircon indicate that it experienced magma mixing, which provided large quantities of ore- forming meterials for large- scale polymetallic mineralization.

关 键 词：花岗岩 年代学 地球化学 Hf同位素 虎头崖 东昆仑 

分 类 号：P618.2[天文地球—矿床学] P597.3[天文地球—地质学]