新疆东天山哈尔里克山早二叠世超基性岩墙锆石U-Pb年龄、地球化学特征及其构造意义  

Zircon U-Pb age,geochemical characteristics,and tectonic implications of the early Permian ultrabasic dykes in the Harlik Mountain,east Tianshan,Xinjiang

作　　者：杜晓飞 王威[1,2] 张传林[3] 马华东 朱炳玉[1,2] 邱林 DU Xiaofei;WANG Wei;ZHANG Chuanlin;MA Huadong;ZHU Bingyu;QIU Lin(Xinjiang Natural Resources and Ecological Environment Research Center,Urumqi 830000,Xinjiang,China;The National 305 Project Office of Xinjiang,Urumqi 830000,Xinjiang,China;College of Oceanography,Hohai University,Nanjing 210098,Jiangsu,China)

机构地区：[1]新疆自然资源与生态环境研究中心,新疆乌鲁木齐830000 [2]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 [3]河海大学海洋学院,江苏南京210098

出　　处：《地质力学学报》2025年第1期156-168,共13页Journal of Geomechanics

基　　金：新疆维吾尔自治区自然科学基金项目(2022D01A144);自治区公益性科研院所基本科研业务费(KY2024112)。

摘　　要：在东天山哈尔里克山发育多期岩浆活动,形成了大面积的花岗岩和超基性岩墙。为限定古亚洲洋在该区的闭合时限,同时阐述超基性岩墙形成的构造环境,文章报道了哈密沁城超基性岩墙(角闪石岩)岩相学、岩石地球化学和锆石U-Pb年龄。研究表明,角闪石岩SiO_(2)含量为39.00%~45.48%、TiO_(2)(1.60%~3.01%)、Mg^(#)在50~60之间,轻稀土相对弱富集((La/Yb)_(N)=1.34~2.25)),铕异常不明显(δEu=0.76~1.12),富集大离子亲石元素(Rb、Ba、K、Sr),相对亏损高场强元素(Nb、Zr、Hf)。角闪石岩属于碱性系列岩石,3件角闪石岩样品的LA-MC-ICPM_(S)锆石U-Pb年龄分别为298.4±1.7 Ma、297.7±1.6 Ma、295.5±1.6 Ma。全岩Sr-Nd组成表明,岩石初始^(87)Sr/^(86)Sr比值为0.7047~0.7051之间,εNd(t)变化范围在-2.63至+1.81之间。结合对区域地质、年代学、元素地球化学以及Sr-Nd同位素等资料的全面分析,认为沁城早二叠世角闪石岩原岩的岩浆可能起源于岩石圈地幔的部分熔融,形成于后碰撞伸展环境下,同时,暗示哈尔里克山地区古亚洲洋在早二叠世之前闭合。[Objective]During multiple stages of magmatic activity in the Harlik Mountains of the east Tianshan,extensive granitic and mafic dyke swarms were formed.This study aims to constrain the closure time of the Paleo-Asian Ocean in this area and to elucidate the tectonic environment in which ultrabasic dykes were formed.[Methods]This study reports petrography,geochemistry,and zircon U-Pb ages of a particular type of ultrabasic dyke swarms(amphibolites)in Qincheng,Hami.[Results]The amphibolites have SiO_(2) contents from 39.00%to 45.48%,TiO_(2) contents from 1.60%to 3.01%,and Mg^(#) values from 50 to 60.They are relatively weakly enriched in light rare earth elements(La/Yb)_(N)=1.34~2.25))and show no Eu anomalies(δEu=0.76~1.12).They are enriched in large ion lithophile elements(LILEs:Rb,Ba,K,Sr)and depleted in high field strength elements(HFSEs:Nb,Zr,Hf).The amphibolites belong to the alkaline rock series.LA-MC-ICP-M_(S)zircon U-Pb dating reveals that these three amphibolites crystallized at 298.4±1.7 Ma,297.7±1.6 Ma,and 295.5±1.6 Ma,respectively.Whole rock Sr-Nd analysis reveals initial ^(87)Sr/^(86)Sr ratios from 0.7047 to 0.7051 andεNd(t)values from-2.63 to 1.81.[Conclusion]Based on the comprehensive analysis of regional geology,chronology,geochemistry,and Sr-Nd isotopes,it is suggested that the primitive magma of the early Permian amphibolites in Qincheng may have been created by partial melting of the lithospheric mantle,and these rocks were formed in a post-collisional extensional tectonic setting.It is furthermore implied that the Paleo-Asian Ocean in the Harlik Mountains region closed before the early Permian.

关 键 词：角闪石岩 LA-MC-ICPMS U-Pb测年 SR-ND同位素 地球化学特征 哈密 

分 类 号：P588.1[天文地球—岩石学] P597[天文地球—地质学]