摘要
四川李家沟伟晶岩型锂铌钽铍锡稀有金属矿床位于松潘-甘孜造山带中部、可尔因矿田东南部,是近年新发现的超大型矿床,成矿时代尚不清楚。本文在伟晶岩地质特征研究的基础上,对李家沟锂辉石伟晶岩中的锡石矿物开展电子探针成分分析以及LA-MC-ICP-MS U-Pb定年工作。电子探针波谱定量分析结果显示,李家沟矿床的锡石都是与稀有金属矿床有关的锡石,并非来自热液矿床的锡石。U-Pb定年结果显示,含锂辉石钠长石伟晶岩样品(LPD4H2)的207 Pb/206 Pb-238 U/207 Pb谐和年龄为211.4±3.3 Ma(n=28,MSWD=2.9),可以代表稀有金属伟晶岩脉的年龄。表明李家沟稀有金属矿床形成于晚三叠世,与印支晚期的岩浆热液活动密切相关。区域成岩成矿年代学对比显示,李家沟与雪宝顶和甲基卡等矿床具有相似的成矿类型和成矿年龄,形成于造山后趋于稳定阶段。松潘-甘孜造山带印支晚期-燕山早期存在大规模的锂铌钽铍锡稀有多金属成矿事件。
The Lijiagou deposit in the southwest of Ke eryin orefield,Sichuan Province is a newly discovered pegmatite-type rare-metal deposit within the central Songpan-Garze fold belt(SGFB),while its age of formation and mineralization of the pegmatite remains unclear.To address these issues,based on the geological characteristics of pegmatite in Lijiagou deposit,this work analyzed major chemical compositions and made laser ablation multicollector inductively coupled plasma mass spectrometry(LA-MC-ICP-MS)dating of cassiterite.Electron-microprobe analyser(EMPA)analyses indicate that the cassiterite from the Lijiagou deposit is related to the rare-metal deposit,not from the hydrothermal deposit,which can represent the age of the rare metal deposit.The cassiterite has a Tera-Wasserburg lower intercept age of 211.4±3.3 Ma(n=28,MSWD=2.9),which represents the emplacement age of the pegmatite dikes.The results indicate that the Lijiagou rare metal deposit was formed in the Late Triassic and was closely related to the magmatic hydrothermal activity in the late stage of the Indosinian period.The regional metallogenic ages comparison shows that the Xuebaoding,Lijiagou and Jiajika deposits have similar mineralization ages,similar mineralization types,and formed in a post-orogenic stable tectonic setting.Large-scale Li-Be-Nb-Ta-Sn rare-metal polymetallic events occurred in the Late-Indosinian and Early Yanshanian in the SGFB.
作者
许家斌
费光春
覃立业
杨继忆
郑硌
唐文春
XU Jiabin;FEI Guangchun;QIN Liye;YANG Jiyi;ZHENG Luo;TANG Wenchun(106 Team of the Sichuan Bureau of Geology and Mineral Resources Exploration,Wenjiang,Sichuan 611130;Key Laboratory of Tectonic Controls on Mineralization and Hydrocarbon Accumulation,Ministry of Natural Resources,College of Earth Science,Chengdu University of Technology,Chengdu,Sichuan 610059;Sichuan Energy Investment Lithum Technology Co.Ltd,Chengdu,Sichuan 610023;Geochemistry Exploration Team of the Sichuan Bureau of Geology and Mineral Resources Exploration,Deyang,Sichuan 618000)
出处
《地质与勘探》
CAS
CSCD
北大核心
2020年第2期346-358,共13页
Geology and Exploration
基金
国家自然科学基金项目(编号:41702074)
四川省科技厅应用基础研究项目(编号:2019YJ0285)
四川省教育厅自然科学重点项目(编号:17ZA0039)
成都理工大学中青年教学骨干教师资助项目(编号:JXGG201701)联合资助。
