东昆仑东段益克郭勒铜多金属矿床花岗岩类锆石U-Pb年龄、地球化学特征及地质意义  

Zircon U-Pb ages and geochemical characteristics of Granitoids in the Yikeguole copper-polymetallic deposit, in the eastern section of the East Kunlun and their geological significances

作　　者：韩芝弘 夏楚林[1,2] 杜瑜 李生虎 张文昭 甄士坤 全长恩 HAN Zhi-hong;XIA Chu-lin;DU Yu;LI Sheng-hu;ZHANG Wen-zhao;ZHEN Shi-kun;QUAN Chang-en(Department of Geological Engineering,Qinghai University,Xining 810016,China;Key Lab of Cenozoic Resource and Environment in the North Margin of the Tibetan Plateau,Xining 810016,China;The Fifth Geological Exploration Institute of Qinghai Province,Xining 810099,China)

机构地区：[1]青海大学地质工程系,西宁810016 [2]青藏高原北缘新生代资源环境重点实验室,西宁810016 [3]青海省第五地质勘查院,西宁810099

出　　处：《矿物岩石地球化学通报》2023年第1期215-232,共18页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：青海省科技计划项目(2020-ZJ-762)。

摘　　要：益克郭勒铜多金属矿床位于东昆仑成矿带东段,矿区花岗岩类发育,构造-岩浆活动频繁。为进一步确定矿区岩浆-热液活动时代及岩浆活动与矿床形成的关系,通过激光剥蚀电感耦合等离子质谱仪(LA-ICP-MS)锆石U-Pb定年,测得矿区1件花岗闪长岩样品和1件英云闪长岩样品的加权平均年龄分别为(249.79±0.91)Ma和(248.83±0.88)Ma,指示其形成于早三叠世。岩石地球化学分析结果表明,益克郭勒侵入岩的SiO_(2)含量为61.93%~71.22%,Na_(2)O/K_(2)O为0.65~1.53,σ为1.29~1.88,A/CNK为0.25~1.09,显示铝质高钾钙碱性特征;岩石轻重稀土分异较显著,Eu显示弱正异常,Rb、Ba、Th、U等大离子亲石元素出现“峰”,高场强元素Nb、P、Ti等呈“谷”,属I型花岗岩。研究认为,该花岗岩类的物源为以角闪石为主残留相的下地壳部分熔融,并有幔源物质的参与。成岩构造环境为大陆边缘弧环境,推测与布青山-阿尼玛卿洋向北俯冲有关,是古特提斯洋在早三叠世向北俯冲于东昆仑地块之下的响应。The Yikeguole copper-polymetallic deposit is located in the eastern section of the East Kunlun. Granitoids are widely distributed and tectono-magmatic activities occurred frequently in the area. In order to further determine the age of magmatic-hydrothermal activity in the deposit area and the relationship between magmatic activity and the formation of ore deposits, we have carried out the LA-ICP-MS U-Pb dating of zircons from granodiorite and tonalite samples in the deposit area and have obtained weighted average ages of(249.79 ± 0.91) Ma and(248.83 ± 0.88) Ma, respectively, indicating that they were formed in the Early Triassic. Petrogeochemical analytical results show that intrusive rocks in the Yikeguole area have SiO_(2)contents varying from 61.93% to 71.22%, Na_(2)O/K_(2)O ratios varying from 0.65 to 1.53, σ values varying from 1.29 to 1.88, and A/CNK ratios varying from 0.25 to 1.09, showing characteristics of the aluminous high-K calc-alkaline series. They have obvious fractionation between LREE and HREE, with weak positive Eu anomaly. They are characterized with “peaks” of large ion lithophile elements including Rb, Ba, Th, and U, and“valleys” of high field strength elements including Nb, P and Ti. They belong to the I-type granite. It is believed that they could be mainly originated from the partial melting of the lower crust which has the main residual phase of hornblende, with minor mantle-derived materials. They were formed in the continental margin arc environment which is inferred to have been related to the northward subduction of the Buqingshan-Animaqing Ocean, corresponding to the northward subduction of the Paleo-Tethys Ocean under the East Kunlun Block in the Early Triassic.

关 键 词：锆石U-Pb定年 岩石地球化学特征 I型花岗岩 益克郭勒铜多金属矿 东昆仑成矿带 

分 类 号：P597[天文地球—地球化学]