贵州东部及邻区铁丝坳组层序及沉积环境成因

THE STRATIGRAPHIC SEQUENCE AND ORIGIN OF THE DEPOSITIONAL ENVIRONMENTS OF THE TIESI’AO FORMATION IN EASTERN GUIZHOU AND ITS ADJACENT AREAS

摘要: 一、前言分布在贵州东部及邻区的铁丝坳组,大致相当于早震旦世古城期沉积,1978年以来,曾有“小冰”之称。王砚耕和马国干在创建本组时,认为是一种特殊的“冰海相”沉积（1981）;后经我们近三年来的工作所见,大量事实与冰川成因不符。为促进这方面的研究,笔者在本文中主要讨论该组的相环境和成因问题。二、铁丝坳组的地层序列本文所涉及的范围是贵州省东部及其毗邻的四川东南隅和湖南西部。铁丝坳组分布较广,出露良好（图1）。限于以往研究程度较低,对其层序和横向延伸情况的认识尚存在问

Abstract: The Tiesi’ao Formation, deposited in Guchengian time （early Sinian）, is well developed in eastern Guizhou and its adjacent areas. It is mainly repre- sented by marine clastic strata made up of diamictite and sandstone. The stra- tigraphic sequence may be continuous or discontinuous. According to its lithology, sedimentary structure and textures, vertical se- quence, components, regional changes and geological setting, the authors believe that this formation is not continental glacial or marine glacial sediments, but marine gravity flow sediments, i. e. channel and interchannel sediments. Its paleoenvironments belong to continental margins at the juncture of the con- vergent plates, i.e. Andean-type mobile continental margins （continental slope）.