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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

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.