Reconstruction off preglacial topography using a postglacial flooding surface; Upper Paleozoic deposits, Central Transantarctic Mountains, Antarctica
Reconstruction off preglacial topography using a postglacial flooding surface; Upper Paleozoic deposits, Central Transantarctic Mountains, Antarctica
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使用冰后洪水表面重建冰前地形；
DOI：
10.1306/d426854a-2b26-11d7-8648000102c1865d
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发表时间：
1997
影响因子：
2
通讯作者：
Gina M. Seegers
中科院分区：
文献类型：
--
作者：
J. Isbell;Greg A. Gelhar;Gina M. Seegers
南极横贯山脉中部的上古生界冰川沉积是沿南极东部克拉通边缘形成的晚古生代至早中生代盆地内的基底沉积。这个盆地在其历史的大部分时间里都是一个前陆盆地，它是一个更大的盆地的一部分，这个盆地横跨古太平洋冈瓦纳大陆的边缘。我们对横贯南极山脉中部冰川前地形的重建表明，沉积始于位于下古生代罗斯造山带侵蚀岩石顶部的两个地形洼地。等厚层、古海流和岩相资料支持这样的假设。这一解释表明，构造活动不是沉积盆地形成的一个因素，在冰川沉积期间，邻近大陆边缘的构造活动很少或没有发生。尽管沿南极洲和冈瓦纳大陆的古太平洋大陆边缘都有冰川沉积物，但我们的研究结果表明，最初的沉积始于一系列不连续的沉积中心。在横贯南极山脉中部，将上古生界冰川沉积与上覆的冰后黑色页岩分开的洪水面被用作重建冰期前地形的基准面。冰后洪水面是冈瓦尼德冰原崩塌后沉积盆地洪水形成的。该方法的研究结果有助于重新评价控制南极洲沉积盆地形成的因素，并确定上古生界冰川沉积时期南极洲古太平洋边缘的构造环境。利用淹水面作为基准面是一种在其他环境下重建古地形时可能有用的技术。
ABSTRACT Upper Paleozoic glacial deposits in the central Transantarctic Mountains are the basal deposits within a late Paleozoic to early Mesozoic basin that formed along the margin of the East Antarctic Craton. This basin was a foreland basin throughout much of its history, and was part of a larger-scale basin that stretched across the paleo-Pacific margin of Gondwanaland. Our reconstruction of the preglacial topography in the central Transantarctic Mountains suggests that deposition began within two topographic depressions located on top of eroded rocks of the lower Paleozoic Ross Orogenic Belt. Isopach, paleocurrent, and lithofacies data support such a hypothesis. This interpretation implies that tectonic activity was not a factor in the formation of the depositional basin, and that little r no tectonic activity was occurring along the adjacent continental margin during glacial deposition. Although glacial deposits are present all along the paleo-Pacific continental margin of Antarctica and Gondwanaland, our findings suggest that initial sedimentation began within a series of discontinuous depocenters. A flooding surface that separates upper Paleozoic glacial deposits from overlying postglacial black shales in the central Transantarctic Mountains is used as a datum for reconstructing the preglacial topography. The postglacial flooding surface resulted from flooding of the depositional basin following collapse of the Gondwanide ice sheet. Results using this approach aided us in reevaluating the factors that controlled the formation of the depositional basin in Antarctica and in determining the tectonic setting of the paleo-Pacific margin of Antarctica during deposition of the upper Paleozoic glacial rocks. The use of a flooding surface as a datum is a technique that may be useful for reconstructing paleotopography in other settings.