地壳生长及深部物质架构研究与问题:以中亚造山带(北疆地区)为例  

Studies of Crustal Growth and Deep Lithospheric Architecture and New Issues:Exemplified by the Central Asian Orogenic Belt(Northern Xinjiang)

作　　者：王涛 黄河[1,3] 宋鹏 吴欢欢[1,4] 张建军 童英[1,3] 杜開明 秦切 Wang Tao;Huang He;Song Peng;Wu Huanhuan;Zhang Jianjun;Tong Ying;Du Kaiming;Qin Qie(Key Laboratory of the Deep Earth Geodynamics,Ministry of Natural Resources,Beijing 100037,China;Beijing SHRIMP Center,Beijing 100037,China;Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China;School of Earth Sciences and Resources,China University of Geosciences,Beijing 100038,China)

机构地区：[1]自然资源部深地动力学重点实验室,北京100037 [2]北京离子探针中心,北京100037 [3]中国地质科学院地质研究所,北京100037 [4]中国地质大学地球科学与资源学院,北京100038

出　　处：《地球科学》2020年第7期2326-2344,共19页Earth Science

基　　金：国家重点基础研究发展计划(Nos.2017YFC0601301,2018YFC0603702,2019YFA0708604);国家自然科学基金(Nos.41830216,41802074,U1403291);中国地质调查局项目(Nos.DD20190001,DD20190370,DD20190685);IGCP662项目。

摘　　要：岩浆岩区域多元同位素示踪填图是探索地球深部物质组成架构、研究地壳生长的重要途径.中亚造山带作为全球最大、最典型的显生宙增生型造山带,发育巨量岩浆岩,是研究造山带深部物质组成架构及地壳生长的天然实验室.介绍了在中亚造山带西段的北疆地区同位素示踪填图的成果,并探讨了存在和需要研究的新问题.阿尔泰-准噶尔-天山的花岗岩同位素廊带填图初步揭示,阿尔泰中部深部物质较老,准噶尔年轻,东天山-北山更老,这种物质组成结构是同造山水平生长和后造山垂向生长的结果.西天山及邻区Hf同位素填图揭示了同一微陆块内部复杂的新老地壳组成架构,提出周期性地壳生长/再循环模式.同位素填图揭示的深部物质组成类型——尤其是年轻地壳的组成类型——仍需进一步探索.需要探索多元同位素示踪、填图结果的异同、关联性及其影响因素,并与地球物理探测、岩石学实验模拟结果相结合,最终构建以岩石探针和同位素示踪填图为核心的,结合地球物理探测、深部钻探和深部过程模拟的岩石圈三维物质与结构探测的理论和技术方法体系.Multiple isotopic mapping of magmatic rocks is a useful tool to unveil the architecture and composition of the deep lithosphere of orogens and to study the crustal growth.As the world’s largest and most typical accretionary orogenic belt,the Central Asian Orogenic Belt(CAOB)is an ideal natural laboratory for addressing the scientific issues mentioned above.In this contribution,we synthetically exhibit the recent achievements in isotopic mapping being carried out in northern Xinjiang,SW CAOB,and discuss the relevant issues.Cross-section of Nd-Hf isotopic data across the Altai-Junggar-Tianshan-Beishan orogens preliminarily indicate that some ancient materials are distributed in the central Altai,the Junggar is composed mostly of juvenile components,and the most ancient crustsare found in Eastern Tianshan-Beishan areas.These differences can be attributed to the combination of lateral continental crust growth at the syn-accretionary stage and the vertical growth at late-to post-accretionary stages.The Hf isotopic mapping of felsic rocks in the Western Tianshan and adjacent regions reveals a within-microcontinental heterogeneity in lithospheric architecture,and alternating occurrence in space and time of juvenile and ancient crustal components implies periodic continental growth and reworking.Details of components in the deep lithosphere probed by isotopic mapping,juvenile crustal endmembers particularly,require further studies.We need to explore the results of multi-proxy isotopicsystems and understand the mechanism behind the similarities and differences.Furthermore,deep lithospheric compositions traced by multiisotopes should be in agreement with geophysical data as well as experimental petrology.Our ultimate goal is to establish a multidisciplinary approach with multi-isotopic mapping as the core,including geophysical detection,deep drilling,and simulation of deep process.

关 键 词：岩浆岩 同位素填图 深部物质组成 中亚(北疆) 地球物理 

分 类 号：P541[天文地球—构造地质学] P548[天文地球—地质学]