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引用本文:李晓光,弓小平,裴国栋,韩琼,赵同阳,郑加行. 阿尔泰造山带喀纳斯群变质碎屑岩地球化学特征及年代学研究[J]. 中国地质, 2018, 45(2): 319-333.
LI Xiaoguang,GONG Xiaoping,PEI Guodong,HAN Qiong,ZHAO Tongyang,ZHENG Jiaxing. Geochemistry and geochronology of metamorphic rocks in Kanas Group, Altay orogenic belt[J]. Geology in China, 2018, 45(2): 319-333(in Chinese with English abstract).
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阿尔泰造山带喀纳斯群变质碎屑岩地球化学特征及年代学研究
李晓光1, 弓小平1, 裴国栋1, 韩琼2, 赵同阳2, 郑加行2
1.新疆大学地质与矿业工程学院, 新疆 乌鲁木齐 830049;2.新疆维吾尔自治区地质调查院, 新疆 乌鲁木齐 830010
摘要:
喀纳斯群为一套巨厚的中低压型浅变质碎屑岩系,主要由片岩、片麻岩、变质砂岩等组成,其形成时代未有统一的认识,致使阿尔泰构造带的构造演化过程争议较大。对喀纳斯群变质岩进行原岩恢复,认为该套变质岩为副变质岩,考虑到变质碎屑岩的成岩物质继承母岩特征和变质程度的影响,利用碎屑岩研究方法对元素地球化学特征进行探讨,显示出喀纳斯群变质碎屑岩原岩形成环境以大陆岛弧为主,兼有活动大陆边缘的特征,CIA、ICV指数反应出原岩经历了相对温暖、湿润的风化作用,成熟度较低。锆石U-Pb定年结果表明,最年轻的锆石年龄集中在(500±3.0)Ma,代表喀纳斯群的上限年龄,认为该套地层形成于晚寒武世晚期之前,为一套形成于大陆岛弧或活动大陆边缘的复理石建造。新元古代青白口纪初期基底裂解事件,暗示着阿尔泰构造带存在前寒武纪大陆地壳基底。
关键词:  阿尔泰造山带  喀纳斯群  变质碎屑岩  副变质岩  大陆岛弧  晚寒武世晚期
DOI:10.12029/gc20180208
分类号:P541
基金项目:国家自然科学基金项目“新疆东准噶尔卡拉麦里金矿带成矿流体特征及其与侵入体的关系研究”(41462004)和中国地质调查局项目“阿尔泰-准噶尔北缘成矿带矿产资源调查成果集成专题”(12120113041900)联合资助。
Geochemistry and geochronology of metamorphic rocks in Kanas Group, Altay orogenic belt
LI Xiaoguang1, GONG Xiaoping1, PEI Guodong1, HAN Qiong2, ZHAO Tongyang2, ZHENG Jiaxing2
1.College of Geology and Mining Engineering, Xinjiang University, Urumqi 830049, Xinjiang, China;2.Xinjiang Institute of Geological Survey, Urumqi 830010, Xinjiang, China
Abstract:
Kanas Group is composed of a set of thick low pressure type shallow metamorphic rocks, mainly comprising schist, gneiss, and metamorphic sandstone; nevertheless, its formation time is in debate, resulting in the controversy concerning the tectonic evolution of Altay tectonic belt. The restoration of Kanas metamorphic protolith reveals that the metamorphic rocks are parametamorphic rocks. In consideration of the influence of inheriting parent rock features of rock materials and degree of metamorphism of metamorphic rocks, the authors investigated the element geochemical characteristics of clastic rocks by using research methods for clastic rocks, and the results show that the protolith of Kanas Group metamorphic rocks was formed in an environment of continental arc and also had characteristics of active continental margin. CIA, ICV indexes show that the original rocks experienced relatively warm and humid weathering process, with low maturity. The zircon U-Pb data show that the youngest zircon age is(500 ±3.0)Ma, which represents the upper limit age of Kanas Group, and that the strata were formed before late Cambrian, being a flysch formation produced in an environment of continental island arc or active continental margin. The breakup of Neoproterozoic Qingbaikouan early basement suggests that the Altay tectonic belt had Precambrian continental crust basement.
Key words:  Altay orogenic belt  Kanas Group  metasedimentary rocks  parametamorphic rocks  continental island arc  Late Cambrian