塔东地区寒武纪—早奥陶世古地理格局新认识

New Understanding of Cambrian- Early Ordovician Palaeogeographical Pattern in the Eastern Tarim Basin

沉积岩石学的研究与实践充分说明(准同生)白云岩是潮坪、潟湖、局限台地、蒸发台地等浅水环境的产物;煤岩学研究与实践也充分说明,石煤炭质泥岩及含磷岩系(如磷块岩)是浅水或近地表滞留环境如潮坪、沼泽、潟湖等环境的产物;尤其是准同生白云岩与(含石煤)炭质泥岩共生,更是浅水环境的有力证据。为此,以(准同生)白云岩、(含石煤)炭质泥岩等特殊岩石类型为基本沉积环境标志,在露头、钻井、地球物理、室内分析等多种研究成果的基础上,对塔里木盆地东部地区寒武纪—早奥陶世的沉积环境进行了研究,认为塔里木盆地东部寒武纪—早奥陶世为浅水沉积环境,从而对塔里木盆地的古地理格局提出了新的认识,即"东高西低,东沼西潟"。

Sedimentary petrology research and practice fully indicate that( penecontemporaneous) dolomite is the product of tidal flat,lagoon,restricted platform,evaporation platform and others in shallow- water environment. Coal petrology research and practice also fully show that stone- coal carbonaceous mudstone and phosphoric rock series( such as phosphate) is the product in shallow- water or stranded near- surface environments,such as tidal flat,marsh,lagoon,etc. Especially the symbiosis between penecontemporaneous dolomite and carbonaceous mudstone( include stone coal) is a strong evidence of shallow- water environment. Therefore,the( penecontemporaneous) dolomite,( including stone coal) carbonaceous mudstone and other special rock types are taken as the basic signs of sedimentary environment. The Cambrian- Ordovician sedimentary environments of eastern Tarim Basin are studied based on the researches of outcrops,drilling,geophysics,laboratory test,etc. Research shows that eastern Tarim Basin Cambrian-Ordovician sedimentary belongs to shallow- water sedimentary environment. Then a new understanding for the Tarim Basin palaeogeographical pattern is put forward,which is'high east and low west,east swamp and west saline- alkali'.