阿尔金山冰沟一带花岗岩地球化学特征及对大地构造的演化启示
Geochemical Characteristic of Granite in the Binggou Area of the Altun Mountains and Its Implications for Geological Structure Evolution
王成 1杨子江 2马华东 1娜迪艳·克力木江 1吕宁 1张雅芳3
作者信息
- 1. 新疆自然资源与生态环境研究中心,新疆 乌鲁木齐 830000;新疆维吾尔自治区人民政府国家305项目办公室,新疆乌鲁木齐 830000
- 2. 新疆自然资源与生态环境研究中心,新疆 乌鲁木齐 830000
- 3. 新疆地质矿产科技开发有限责任公司,新疆乌鲁木齐 830000
- 折叠
摘要
本文对出露于阿尔金山冰沟构造岩浆岩带内冰沟序列花岗岩进行了岩石学、地球化学、和锆石SHRIMPU-Pb年代学研究.地球化学特征显示:花岗岩高硅、钠,低铁、镁、钙的特征,铝饱和指数为0.88～1.01,为准铝质"Ⅰ"型花岗岩;富集Rb,Th和LREE,亏损Ta,Nb,Zr,Hf和HREE;大多具负铕异常,δEu值为0.52～0.62.锆石U-Pb定年结果显示:冰沟序列侵入岩中花岗闪长岩年龄为(410.7±11.9)Ma,二长花岗岩年龄为(418.5±9.6)Ma,辉长岩年龄为(449.5±10.9)Ma.结合区域地质、地球化学特征揭示花岗岩岩体形成于后碰撞伸展阶段,认为同碰撞挤压造山阶段向后碰撞伸展转换阶段时间节点约为440 Ma,后碰撞伸展作用和偏碱性岩浆活动时代为440～410 Ma,持续约30 Ma.晚奥陶世北阿尔金古洋盆闭合,在有限洋盆造山带(冰沟序列侵入岩)形成规模较大的消减活动板块边缘(岛弧或活动大陆边缘)构造岩浆岩带.
Abstract
This study presents a detailed petrological,geochemical,and zircon SHRIMP U-Pb geochronological investi-gation of the granite sequences exposed with in the Binggou Tectonic Magmatic Belt in Arjin mountains.The geochemi-cal characteristics show that the granites are characterized by high Si and Na,low Fe,Mg and Ca,and the aluminum satu-ration index(A/CNK)is 0.88-1.01,which is in the metaluminous"Ⅰ"type granite;they are enriched in Rb,Th,and LREE,and are deficient in Ta,Nb,Zr,Hf,and HREE;they mostly have negative europium anomalies,and their δEu val-ues range from 0.52 to 0.62.The zircon U-Pb dating results show that among the intrusive rocks in the Binggou se-quence,granodiorite is(410.7±11.9)Ma,diorite is(418.5±9.6)Ma,and gabbro is(449.5±10.9)Ma.Combined with the regional geologic data,geochemical characteristics,and tectonic interpretation,it is revealed that the granite body should have formed in the post-collisional extension stage,and it is thought that the same collision and extrusion stage of the orogeny was transferred to the post-collisional stage,and the same collision and extrusion stage was transferred to the post-collisional stage,and the same collision and extrusion stage was transferred to the post-collisional stage.It is be-lieved that the transition from co-collision and extrusion to post-collision and extension was around 440 Ma,and the post-collision and extension and alkaline magmatism lasted for about 30 Ma from 440 Ma to 410 Ma.The closure of the an-cient Altun Ocean basin in the north of the late ordovician epoch led to the formation of a large scale subtractive tectonic magmatic belt at the active plate margin(island-arc or active continental margin)in the limited ocean basin orogenic belt(the intrusive rocks in the Binggou sequence).
关键词
阿尔金山/冰沟构造岩浆岩带/地球化学特征/大地构造演化Key words
Arjin mountains/Binggou Tectonic Magmatic Belt/Geochemical characteristics/Geological structure evo-lution引用本文复制引用
基金项目
国家重点研发计划(2021YFC2901900)
新疆三次科考项目(2022xjkk1301-19)
&&(2022xjkk1006)
国家自然科学基金面上项目(42172258)
出版年
2024
NETL
NSTL
万方数据