地学前缘 ›› 2015, Vol. 22 ›› Issue (6): 97-108.DOI: 10.13745/j.esf.2015.06.007

• 前寒武纪地球动力学（VII） • 上一篇    下一篇

前寒武纪地球动力学(Ⅶ)：早期大陆地壳的形成与演化

刘树文,王伟,白翔   

  1. 1. 造山带与地壳演化教育部重点实验室; 北京大学 地球与空间科学学院, 北京 100871
    2. 地质过程与矿产资源国家重点实验室; 中国地质大学(北京) 地球科学与资源学院, 北京 100083
    3. 中国地震局 地质研究所, 北京 100029
    4. 东北大学 资源与土木工程学院, 辽宁 沈阳 110819
  • 收稿日期:2015-10-19 修回日期:2015-10-25 出版日期:2015-11-15 发布日期:2015-11-25
  • 作者简介:刘树文(1958—)，男，博士，教授，博士生导师，从事前寒武纪地质学、岩石学和岩石地球化学研究。E-mail：swliu@pku.edu.cn;swliu1958@163.com
  • 基金资助:

    国家自然科学基金重点项目(41530207)；国家自然科学基金面上项目(41272209,41472165)

Precambrian geodynamics (Ⅶ): Formation and evolution of early continental crust.

  1. 1. Key Laboratory of Orogenic Belts and Crustal Evolution(Ministry of Education); School of Earth and Space Sciences, Peking University, Beijing 100871, China
    2. State Key Laboratory of Geological Processes and Mineral Resources; School of Earth Sciences and Resources, China University of Geosciences(Beijing), Beijing 100083, China
    3. Institute of Geology, China Earthquake Administration, Beijing 100029, China
    4. College of Resources and Civil Engineering, Northeastern University, Shenyang 110819, China
  • Received:2015-10-19 Revised:2015-10-25 Online:2015-11-15 Published:2015-11-25

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摘要：

冥古宙到太古宙大陆地壳主要由花岗质片麻岩区和绿岩带构造单元组成。大量的研究表明，以花岗质岩石出现为标志的大陆地壳最早的碎屑锆石记录为约4.4 Ga，最早的英云闪长质花岗闪长质片麻岩形成于约4.03 Ga，最早的绿岩带层序形成于约3.8 Ga。冥古宙到始—古太古代时期的花岗质片麻岩区主要由英云闪长质奥长花岗质花岗闪长质片麻岩组成(TTG片麻岩)，中—新太古代，尤其是新太古代晚期TTG片麻岩仍然为花岗质片麻岩区的主要岩石组成，但是花岗质片麻岩的成分出现了明显的多样化趋势，最明显的标志就是出现了大量的花岗闪长岩二长花岗岩碱长花岗岩组合。绿岩带的组成较为复杂，早期科马提岩、拉斑玄武岩等铁镁质火山岩占主导地位，组合有BIF等沉积层序，尤其是科马提岩的出现标志着高温地幔岩浆作用占主导作用。而晚期绿岩带科马提岩占的比重已经明显较少，大量出现拉斑玄武质钙碱性玄武质到英安质火山岩和副变质沉积层序，局部出现类玻安岩、埃达克岩的变质火山岩记录。地球动力学体制研究表明，冥古宙到古太古代以地幔柱构造体制占主导地位，从始太古代到古太古代(>3.0 Ga)地幔柱活动和地幔对流使岩石圈不断加厚。在地幔对流沉降部位，由于地幔对流的拖曳使其铁镁质地壳逆冲堆垛并不断增厚，其深部发生麻粒岩相榴辉岩相变质、部分熔融形成初始的大陆地壳花岗质岩石，并孕育了早期高温状态的板块热俯冲。中太古代晚期和新太古代初期形成了以榴辉岩为标志的类现代板片俯冲的构造体制，新太古代末期尽管地幔柱构造体制在局部仍起重要作用，但是类现代板片俯冲构造体制已经成为这一时期主导的动力学体制。

关键词: 冥古宙—太古宙, 大陆地壳, 地幔柱, 板片俯冲, 动力学体制

Abstract:

The Hadean to Paleoarchean continental crust consists of both granitoid gneiss terrenes and greenstone belts. A number of investigations revealed the ~4.4 Ga oldest detrital zircon ages of continental crusts marked by granitic rocks, and the earliest tonalitic and granodioritic gneisses were formed at ~4.03 Ga as well as the oldest greenstone belts at ~3.8 Ga. The Hadean to Paleoarchean granitoid gneiss terranes are chiefly composed of TonaliticTrondhjemiticGranodioritic gneisses (TTG). The TTG gneisses still are major lithological assemblages in the Meso to Neoarchean, however, lithological compositions of granitoid gneiss terranes exhibit significant diversity, especially the late Neoarchean marked by many granodioritemonzogranitesyenogranite suites. The greenstone belts display complicated compositions, komatiitic to tholeiitic rocks dominated during the Eo to Paleoarchean associated with BIF sedimentary sequences, whereas the Meso and Neoarchean greenstone belts decrease the ratios of the utramafic to mafic komatiites but raised the ratios of tholeiitic and calcalkaline mafic to felsic volcanic compositions with BIF and detrital sedimentary sequences, locally, boninitic, Nbriched basaltic and adakitic volcanics that are generally considered as the criteria of slab subductions. Geodynamic investigations suggested that the mantle plume regime dominated in the Hadean to Paleoarchean. The mantle convections and crust/mantle interactions led to the formation and thickening of the lithosphere 3.0 Ga ago. Locally significant thickening of mafic crust in downwelling areas due to dragging of mantle convection and thrusting slice stack in upper levels, leading to granulite to eclogite facies metamorphism and partial melting in deep level, which derived the formation of TTG granitoid magmas and initially hot subductions of bottom slabs. However, the Meso to Neoarchean dynamic regimes appeared dominant modernstyle plate tectonics, which were revealed by the discoveries of more and more eclogites and calcalkaline volcanics although the mantle plume regimes still play important roles locally.

Key words: Hadean to Archean, continental crust, mantle plume, slab subduction, dynamic regimes

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