中国东部二叠纪沉积盆地演化

EVOLUTION OF THE PERMIAN SEDIMENTARY BASINS IN EASTERN CHINA

摘要:

本文所指中国东部包括浙江、福建、江西以及郯庐断裂以南的江苏、安徽地区。区内二叠系发育较好,分布较广,同时赋存有丰富的矿产资源,是一重要含矿地层。数十年来,一直为地质学家所注目。本文就中国东部二叠纪沉积盆地演化作一探讨。一、沉积盆地类型中国东部晚古生代沉积盆地系板块内部的盆地,形成于陆壳之上。盆地规模大小不一,基底各不相同,大多为继承性盆地,发育于二叠纪前,至中晚三叠世,受印支运动影响,导致区域性整体上升,海水退出,结束充填。在整个晚古生代,盆地的沉积作用、构造变动、火山活动都表现相对的稳定性,具有克拉通盆地性质。

Abstract:

The study area in the present study occupies five provinces in eastern China, i. e. Fujian, Zhejiang, Jiangxi and parts of Jiangsu and Anhui. The Permian sedimentary basins in eastern China are interpreted as the inherited depressed basins on the continental crust, characterized by less mobility and relative stability (including sedimentation, tectonism and volcanism). Therefore, they have the features of the cratonic basins. These Permian sedimentary basins may be classified into two groups:depressed basins and faulted basins. Their basement comprises the Presinian or Early Palaeozoic metamorphic rocks. Seven sedimentary associations have been distinguished for the sedimentary sequence. They are, from base upwards, lower coal-bearing elastic rock association; lower carbonate rock association; lower siliceous rock association or clastic rock or carbonate rock association; clastic rock association or coal-bearing clastic rock association; upper coal-bearing clastic rock association; upper carbonate rock association, and upper siliceous rock association or carbonate rock or clastic rock association. There is a wide range of the Permian sedimentary environments. The sedimentary facies are complex but are regularly aligned and controlled by the tectonic framework and old land. The evolution of the sedimentary basins may involve four stages. Stage 1 is characterized by transgressive overlap and basin expansion; Stage 2 by basin differentiation and severe basement faulting; Stage 3 by regression and basin shrinkage, and Stage 4 by transgression and basin redifferentiation.