新疆西昆仑509道班西锂矿伟晶岩石英变形特征、温度及其对伟晶岩就位的约束  

Quartz deformation characteristics,deformation temperature,and their constraints on pegmatites of the 509 Daobanxi lithium deposit in the West Kunlun area,Xinjiang

作　　者：霍海龙 陈正乐[1,2,3,4] 张青 王永[1,2] 马华东 王威[3,4] 张文高 李永[6] 韩凤彬 杜晓飞[4,5] 闵壮[1] 孟祥鹏 HUO Hailong;CHEN Zhengle;ZHANG Qing;WANG Yong;MA Huadong;WANG Wei;ZHANG Wengao;LI Yong;HAN Fengbin;DU Xiaofei;MIN Zhuang;MENG Xiangpeng(Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing 100081,China;Key Laboratory of Paleomagnetism and Tectonic Reconstruction of Ministry of Natural Resources,Beijing 100081,China;SinoProbe Laboratory,Chinese Academy of Geological Sciences,Beijing 100094,China;Research Center Resource and Environment of Xinjiang Uygur Autonomous Region,Urumqi 830000,Xinjiang,China;National 305 Project Office of Xinjiang Uygur Autonomous Region,Urumqi 830000,Xinjiang,China;Institute of Geology and Mineral Resources Exploration,Nonferrous Geological Exploration Bureau of Xinjiang Uygur Autonomous Region,Urumqi 830099,Xinjiang,China)

机构地区：[1]中国地质科学院地质力学研究所,北京100081 [2]自然资源部古地磁与古构造重建重点实验室,北京100081 [3]自然资源部深地科学与探测技术实验室,北京100094 [4]新疆自然资源与生态环境研究中心,新疆乌鲁木齐830000 [5]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 [6]新疆维吾尔自治区有色地质勘查局地质矿产勘查研究院,新疆乌鲁木齐830099

出　　处：《地质力学学报》2024年第1期72-87,共16页Journal of Geomechanics

基　　金：国家自然科学基金项目(42172258,42072227);国家重点研发计划项目(2021YFC2901904,2021YFC2901805);新疆维吾尔自治区重大专项项目(2023A03002);中国铀业有限公司-东华理工大学核资源与环境国家重点实验室联合创新基金项目(NRE2021-01);中国地质调查局地质调查项目(DD20221660-3,DZLXJK202206)。

摘　　要：509道班西锂矿床是西昆仑造山带新近发现的大型伟晶岩型锂多金属矿床。作为区内典型的花岗伟晶岩型锂矿床,509道班西锂矿的成矿机制和伟晶岩演化过程对认识整个西昆仑成矿带的成矿作用具有重要意义。作为花岗伟晶岩中的重要矿物,石英是追踪伟晶岩成矿作用过程的理想对象。509道班西矿床的花岗伟晶岩普遍发育强烈的糜棱岩化作用,具有典型的韧性变形特征,通过对糜棱岩化伟晶岩脉进行变形组构分析、石英包裹体测温和石英Ti温度计计算,揭示了与伟晶岩就位相关的大陆地壳变形过程中流体的热力学演化过程,并探讨了韧性变形对区域找矿的启示意义。糜棱岩化伟晶岩中锂辉石、斜长石等矿物主要以脆性破裂为主,具有刚体变形的特征;石英主要发育膨凸重结晶现象,细小的新晶体在较大的石英条带边部形成,可见石英残斑,并具有亚颗粒旋转现象,部分发育核幔构造;白云母普遍变形成云母鱼。石英包裹体、锂辉石和石英的变形特征等微观结构证据表明,糜棱岩化伟晶岩的变形温度为300~400℃,石英Ti温度计得出的变形温度为371~398℃和351~377℃。伟晶岩中石英包裹体的均一温度平均为260~283℃,可能记录了石英变形晚阶段的温度。研究表明,509道班西地区的伟晶岩在侵位过程中经历了一期强烈的低温、高应变速率的韧性变形,伟晶岩就位是快速冷却过程的产物,在高应力和较低温度条件下,动态重结晶(GBM)导致的晶粒粒径减小严重改变了岩石的流变学性质;从~400℃到~260℃的超冷却过程(ΔT=±140℃)中,造成伟晶岩中矿物结晶新核迅速减少,更有利于形成粗大的石英等矿物颗粒,形成伟晶岩脉所有显著特征和独特的岩石结构和矿物组合的空间分带,超冷却在伟晶岩就位过程中具有重要的作用。[Objective]The 509 Daobanxi deposit in the West Kunlun orogenic belt is a newly discovered large pegmatitetype lithium-polymetallic deposit in northwestern China.As a typical granite pegmatite lithium deposit in the region,the metallogenic characteristics and pegmatite evolution of the 509 Daobanxi deposits are of great significance for understanding the entire lithium-polymetallic mineralization process of the West Kunlun metallogenic belt.The granite pegmatites contain assemblages of plagioclase,spodumene,quartz,muscovite,etc.,exhibiting strong mylonization and forming typical ductile deformation characteristics in the 509 Daobanxi deposit.Quartz,an essential mineral in granite pegmatite,is ideal for tracking pegmatite's mineralization process and studying the deformation behavior of continental rocks in long-term geological history.[Methods]To study the late-stage emplacement process of pegmatite evolution,comprehensive analyses were conducted on the quartz deformation structures measurements,fluid inclusion temperature,and quartz trace elements for the 509 Daobanxi granite pegmatites.Cathodoluminescence(CL)analysis of quartz in deformed granite pegmatite samples was performed to reveal the compositional zoning of Ti in quartz.Laser ablation inductively coupled plasma mass spectrometry(LA-ICP-MS)was used to analyze 64 points from samples Zk2707-9 and Zk1107-2.[Results]The minerals of spodumene and plagioclase in deformed pegmatites primarily show brittle fracturing characteristics,with the features of rigid body deformation and the muscovite presence of mica-fish.Meanwhile,the conspicuous feature is that quartz grains mainly develop dynamic recrystallization and contain subgranis.According to the microstructural characteristics of spodumene,plagioclase,and quartz,the deformation temperature of mylonitized granite pegmatite is 300~400℃.The CL images of quartz bands in the granite pegmatite samples have no apparent zoning,indicating that the Ti content reaches a relative equilibrium state in the quartz deforma

关 键 词：糜棱岩化 锂矿床 花岗伟晶岩 509道班西地区 西昆仑 新疆 

分 类 号：P613[天文地球—矿床学] P548[天文地球—地质学]