湘南中晚泥盆世台盆沉积特征及其演化

SEDIMENTARY CHARACTERISTICS AND EVOLUTION OF A MIDDLE AND LATE DEVONIAN INTERPLATFORM BASIN IN SOUTHERN HUNAN

摘要:

湘南地区位于“江南地轴”以南的华南褶皱系。加里东运动后,华南区进入相对稳定的发展阶段,泥盆纪海侵自南西向北东侵入,形成三面环陆的湘桂粤陆棚浅海(曾允孚等,1987)。湘南地区即处于这个沉积盆地的北部东缘。区内泥盆系广泛发育,下泥盆统仅西南江华、道县等地有部分滨岸碎屑沉积;中上统则以碳酸盐岩为主,沉积相类型十分丰富。由于研究区北北东向基底断裂同沉积期的扩张活动,地形起伏较大,形成东西两侧高而中部

Abstract:

The Devonian strata are the first cover deposited posterior to the Caledonian movement in southern Hunan Province where the Middle and Upper Devonian strata are characterized by the prevailing carbonate rocks and variable sedim entary facies types and palaeogeographic features. By means of rock types, textures and structures and biologic assemblages, four sedimentary facies types are recognized, platform facies, interplatform basin facies, platform-margin slope facies and elastic tidal-flat facies, the former three of whic are dealt with in this paper.
The Lingshan-Hengyang interplatform basin, a NE-trending linear strike-slip basin, is a special basin which was developed on a shallow-water carbonate platform, and may be divided into two parts: the Lingshan-Hexian portion controlled by the strike-slip faults and the southern Hunan portion as a tensional-rifted basin. Five stages are identified for the formation and evolution of the interplatform basin. (1) The initial marine basin stage—the Early Devonian to the early Middle Devonian; (2) The primary stage of the interplatform basin differentiation—the late Middle Devonian (the early Qiziqiaoian); (3) The shrinking stage-of the interplatform basin—the late Middle Devonian (the late Qiziqiaoian); (4) The expanding stage of the interplatform basin—the early Late Devonian (the Shetianqiaoian), and (5) The closing-filling stage of the interplatform basin—the late Late Devonian (the Xikuangshanian).