新疆温泉早泥盆世花岗岩锆石U-Pb年龄、Hf同位素及其地质意义  

Zircon U-Pb-Hf Isotopic Compositions and Their Geological Significance of Early Devonian Granites in Wenquan,Xinjiang

作　　者：贾莹刚 赵军 关力伟 杜古尔·卫卫 陈有炘[3] 陈剑[1] Jia Yinggang;Zhao Jun;Guan Liwei;Duguer Weiwei;Chen Youxin;Chen Jian(School of Engineering and Technology,China University of Geosciences(Beijing),Beijing 100083,China;Center of Urumqi Natural Resources Comprehensive Survey,CGS,Urumqi 830057,China;School of Earth Science and Land Resources,Chang’an University,Xi’an 710054,China)

机构地区：[1]中国地质大学(北京)工程学院,北京100083 [2]中国地质调查局乌鲁木齐自然资源综合调查中心,乌鲁木齐830057 [3]长安大学地球科学与资源学院,西安710054

出　　处：《吉林大学学报（地球科学版）》2023年第4期1132-1148,共17页Journal of Jilin University：Earth Science Edition

基　　金：国家自然科学基金项目(41802234);陕西省自然科学基础研究计划项目(2019JQ-209);中央高校基本科研业务费专项资金项目(300102279104);中国地质调查局项目(12120115041301)。

摘　　要：新疆温泉地区位于伊犁地块北缘,出露较多的晚古生代酸性侵入岩类。为研究这些岩浆岩的成因,探讨区域构造演化过程,对温泉地区早泥盆世花岗岩开展了系统的锆石U-Pb年代学、Lu-Hf同位素和地球化学研究,并讨论其地质意义。研究结果表明:二长花岗岩LA-ICP-MS锆石U-Pb定年结果为(418±7)Ma,表示其为结晶年龄,二长花岗岩为早泥盆世岩浆活动的产物;高的εHf(t)值(8.2~14.0,平均值为11.3),年轻的二阶段模式年龄(T_(DM2)为863~492 Ma),暗示花岗岩熔融源区主要为新增生的壳源物质;花岗岩样品具有高硅、相对富钾、弱过铝质、贫钙和镁等主量元素特征,亏损Nb、Ti、P等高场强元素和Ba、Sr,富集K、Rb等大离子亲石元素,具有强烈的负铕异常;花岗岩样品具有较低的锆石饱和温度,P_(2)O_(5)和SiO_(2)质量分数呈明显负相关,指示其为I型花岗岩。微量元素构造环境判别图解显示其形成于陆弧环境,结合区域大地构造背景及邻区岩浆岩演化信息,推测温泉地区早泥盆世花岗岩形成于准噶尔—巴尔喀什洋俯冲环境。There are numerous Late Paleozoic acidic intrusive rocks in Wenquan area,which is located on the northern margin of the Yili block.In this paper,we present new zircon U-Pb geochronology,Lu-Hf isotopic and geochemical studies of the Early Devonian granites from Wenquan area,aiming to confirm their timing,discuss their petrogenesis,and explore their tectonic evolution process.The zircon LA-ICP-MS U-Pb age of the monzogranites is(418±7)Ma which indicates that their crystallization age is the product of Early Devonian magmatic activity.Meanwhile,the zircon Hf isotope compositions of the monzogranite are typically characterized by highεHf(t)values(8.2-14.0,with an average of 11.3),and the young two-stage model ages(T_(DM2)=863-492 Ma),implying their derivation from a relatively juvenile crust.These two types of granites are characterized by high SiO_(2),weakly peraluminous,as well as low CaO and MgO contents.The trace elements of the granites are characterized by depletion in high field strength elements(Nb,Ti,P),and enrichment in large ion lithophile elements(K,Rb).The standardized distribution pattern of rare earth elements in chondrites is enriched in light rare earth elements and depleted in heavy rare earth elements,with significant negative Eu anomalies.The low zircon saturation temperature,negative correlation between P_(2)O_(5) and SiO_(2),and other geochemical features suggest the granites are I-type granites.Several tectonic discrimination diagrams shows that they were formed in a continental magmatic arc setting.Combined with the regional tectonic background and the evolution information of magmatic rocks in the adjacent area,it is speculated that the granites were mainly derived from the crustal accretion in response to subduction of the Junggar-Balkhash Ocean.

关 键 词：锆石U-PB年龄 锆石HF同位素 地球化学 I型花岗岩 早泥盆世 伊犁地块 

分 类 号：P59[天文地球—地球化学] P588.12[天文地球—地质学]