新疆可可托海伟晶岩田岩浆活动时限与伟晶岩形成  

Constraints on Timing of Magmatic Activity and Formation of Pegmatite in the Koktokay Pegmatite Field,Xinjiang

作　　者：闫军武[1,2] 刘锋 申颖[3] 张志欣 YAN Jun-wu;LIU Feng;SHEN Ying;ZHANG Zhi-xin(Geophysical and Geochemical Prospecting Party,Xinjiang Bureau of Geo-exploration and Mineral Development,Changji,Xinjiang 831100;MNR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037;Shandong Institute of Geological Sciences,Jinan,Shandong 250013;Xinjiang Institute of Ecology and Geography,Xinjiang Research Center for Mineral Resources,Chinese Academy of Sciences,Urumqi,Xinjiang 830011)

机构地区：[1]新疆维吾尔自治区地质矿产勘查开发局地球物理化学探矿大队,新疆昌吉831100 [2]中国地质科学院矿产资源研究所,自然资源部成矿作用与资源评价重点实验室,北京100037 [3]山东省地质科学研究院,山东济南250013 [4]中国科学院新疆生态与地理研究所,新疆矿产资源研究中心,新疆乌鲁木齐830011

出　　处：《地球学报》2020年第5期663-674,I0002-I0005,共16页Acta Geoscientica Sinica

基　　金：公益性科研院所基本科研业务费专项资金项目(编号:JYYWF20180104);国家自然科学基金面上项目(编号:41273017);自然资源部公益性行业科研专项课题(编号:200911007-10)联合资助。

摘　　要：可可托海伟晶岩田是新疆阿尔泰造山带内众多伟晶岩田中最重要的伟晶岩集中区。区内发育大量花岗岩体和伟晶岩脉。本文针对出露于该岩田中部—西部区域的4个不同岩相的花岗岩体以及3号伟晶岩脉石英-锂辉石带开展了锆石U-Pb的LA-ICP-MS测年研究,获得了变质黑云母二长花岗岩、变质细中粒黑云母花岗闪长岩、似斑状中粒二云母花岗岩和黑云母花岗岩的加权平均年龄分别为(408.9±1.1)Ma(MSDW=1.7)、(398.6±1.3)Ma(MSDW=0.67)、(395.5±1.3)Ma(MSDW=0.50)和(388.4±1.1)Ma(MSDW=1.8),3号脉石英-锂辉石带中的锆石样品加权平均年龄为(209.4±1.3)Ma(MSDW=0.33)。综合前人大量可靠的年代学成果,表明可可托海伟晶岩田内存在两期岩浆活动:早泥盆世到中泥盆世时期包括基性和酸性岩浆的侵入,其峰值在400 Ma左右。另一期则是三叠纪中—晚期(218-210 Ma)发育的花岗岩浆及与之有成因联系的伟晶岩岩浆-热液(211-202 Ma)的侵入活动,它们构成了一个完整的花岗-伟晶岩体系。The Koktokay pegmatite field is the most important pegmatite area in the Altay Orogenic Belt in Xinjiang.A large number of granites and pegmatite dikes are developed in this field.The authors carried out zircon U-Pb LA-ICP-MS dating for four different granitic plutons occurring in the middle-west field and quartz-spodumene zone in the No.3 pegmatite vein.Several weighted average ages were obtained with(408.9±1.1)Ma(MSDW=1.7)for metamorphic biotite monzogranite,(398.6±1.3)Ma(MSDW=0.67)for metamorphic biotite granodiorite,(395.5±1.3)Ma(MSDW=0.50)for porphyritic mica granite,(388.4±1.1)Ma(MSDW=1.8)for biotite granite and(209.4±1.3)Ma(MSDW=0.33)for quartz-spodumene zone,respectively.Based on many reliable chronological achievements from previous researchers,the authors suggest two periods of magmatic activities in the Koktokay Pegmatite Field.One is the Early–Middle Devonian mafic and acid magmatic intrusion with the peak of 400 Ma,and the other is the Middle–Late Triassic intrusions of granitic magma(218–210 Ma)and related pegmatite magma-hydrothermal activity(211–202 Ma),which constitute a complete granite-pegmatite system.

关 键 词：可可托海 花岗岩 伟晶岩 锆石LA-ICP-MS定年 

分 类 号：P597.2[天文地球—地球化学] P581[天文地球—地质学]