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试论陆壳增生的两种基本模式及其对比

竺国强 程晓敢 杨树锋 陈汉林   

  1. 浙江大学地球科学系
  • 收稿日期:1997-12-20 修回日期:1997-12-20 出版日期:1997-12-20 发布日期:1997-12-20

TWO TYPES OF BASIC MODELS FOR CONTINENTAL CRUST ACCRETION AND THEIR COMPARISON

Zhu Guo-qiang, Cheng Xiao-gan, Yang Shu-feng, Chen Han-lin   

  1. Department of Earth Sciences, Zhejiang University
  • Received:1997-12-20 Revised:1997-12-20 Online:1997-12-20 Published:1997-12-20

摘要: 大陆地壳是地球形成演化的必然产物。大陆地壳由不同时代、不同类型、不同规模地体的拼贴而增生;同时已形成的大陆地壳沿着新的断裂分裂、离散而碱小。因此大陆地壳是地体拼贴增生与分裂离散的综合结果。太古代早期,原始陆壳形成后,主要通过环太平洋型与天山型两种基本模式达到陆壳的增生。环太平洋型陆壳增生模式出现于陆块的边缘,由古大陆向大洋方向单向增生,增生年代由老到新,增生地体一般都有较大距离的移置,其增生与板块的俯冲作用密切有关。天山型陆壳增生模式出现在陆块的内部,其形成与陆块的开台作用密切有关,可以但不一定伴随有俯冲作用。当古大陆沿一定方向断裂带分裂、离散。其间形成新的海槽接受碳酸盐岩和正常陆源碎屑沉积物与来自地壳深部或地幔的火山物质。由于壳下应力条件改变,两侧古陆相向运动,海槽中物质受两侧古陆碰撞挤压,形成褶皱造山带,并把两侧的古大陆“焊接”成新的、范围更大的大陆地壳。

Abstract: Continental Crust is the inevitable product of formation and evolution of the Earth. The Continental Crust is accreted by merging of terranes of different ages, types and scales, and wanes by dividing and separating of prior Continental Crust along new fault system. Hence the formation of Continental Crust is a synthetic result of terrane accretion and separation. The initial Continental Crust was formed during the early Archaean. Since then, the Continental Crust was accreted by two types of basic models, i.e. the Circum-Pacific type and the Tianshan type. The Circum - Pacific type model of continental Crust accretion occurs on continental margins. It is an one-way accreting from old continent to ocean, which the ages of accretion are getting younger along this direction. Generally, the accreted terranees has traveled for a long distance. The accretion is closely related to plate subduction. The Tianshan type of Continental Crust accretion model is developed between continents. Its formation is related to open-closing process of continental crust and may or may not accompany with subduction. When old continent was divided and separated along the faults with certain directions, new trough was formed between separated continents and carbonate rock, normal terrigenous elastic sediment and volcanic material from deep part of Crust Mantle were precipitated. Due to changing of stress condition under Crust, two separated old Continental Crusts moved in opposite direction, the material in trough collided to form fold-orogenic zones, and thus the welding of old Continental Crust from two sides form a new Continental Crust of larger scale.