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Evolution, Migration, Controlling Fa

时间:2021-12-09 13:20:11 天文地理论文 我要投稿

Evolution, Migration, Controlling Factors and Forming Setting of Mesozoic Basins in Western Shandong

The distinctive topography in western Shandong province consists of several NW-WNW-trending mountain ranges and intervening basins.Basins,in which late-stage sediments to the south have progressively overlapped the earlier sediments and "basement" rocks of the hanging-wall block,are bounded by S-SW-dipping normal faults to the north.Basin analysis reveals the Jurassic-Cretaceous sedimentary rocks accumulated both within the area of crustal extension and during extensional deformation; they contain a record of a sequence of tectonic events during stretching and can be divided into four tectonic-sequence episodes.These basins were initially developed as early as ca.200 Ma in the northern part of the study area,extending dominantly N-S from the Early Jurassic until the Late Cretaceous.Although with a brief hiatus due to changes in stress field,to keep uniform N-S extensional polarity in such a long time as 130 Ma requires a relatively stable tectonic controlling factor responsible for the NW- and E-W-extensional basins.The formation of the extensional basins is partly concurrent with regional magmatism,but preceded magmatism by 40 Ma.This precludes a genetic link between local magmatism and extension during the Mesozoic.Based on integrated studies of basins and deformation,we consider that the gravitational collapse of the early overthickened continental crust may be the main tectonic driver for the Mesozoic extensional basins.From the Early Jurassic,dramatic reduction in north-south horizontal compressive stress made the western Shandong deformation belt switch from a state of failure under shortening to one dominated by extension and the belt gravitationally collapsed and horizontally spread to the south until equilibrium was established; synchronously,the normal faults and basins were developed based on the model of simple-shear extensional deformation.This may be relative to the gravitational collapse of the Mesozoic plateau in eastern China.

作 者: ZHANG Zhongyi Wu Ganguo Guo Jinghui ZHANG Da   作者单位: ZHANG Zhongyi,Wu Ganguo,ZHANG Da(Key Laboratory of Lithospheric Tectonics and Lithoprobing Technology,Ministry of Education,University of Geosciences,Beijing 100083)

Guo Jinghui(Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029) 

刊 名: 地质学报(英文版)  SCI 英文刊名: ACTA GEOLOGICA SINICA  年,卷(期): 2005 79(4)  分类号: P5  关键词: Mesozoic   basin   basin analysis   extension   gravitational collapse   western Shandong