An analysis of the Permo-Carboniferous glaciation in the marine Kalahari Basin, Southern Africa
An analysis of the Permo-Carboniferous glaciation in the marine Kalahari Basin, Southern Africa
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南部非洲海洋卡拉哈里盆地二叠纪-石炭纪冰川作用分析
DOI：
10.1016/0031-0182(83)90108-6
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发表时间：
1983
期刊：
影响因子：
--
通讯作者：
J. Visser
中科院分区：
文献类型：
--
作者：
J. Visser
Dwyka组是卡拉哈里盆地沉积充填物的基底单元，由局部红色基底冰碛岩、含海相化石的页岩、泥岩、粉砂岩、砂岩、杂岩和碳酸盐透镜体和结核的泥质层序以及发育良好的主冰碛岩组成。沿着盆地南缘的Hotazel山谷也存在上部冰碛岩。该序列代表了两个主要的冰的进步分开的一个明确的间冰期和一个小的冰前进局限于周围的地区的冰spreading centre.Glacial最大冰期在晚石炭世的冰川侵蚀形成了一个解剖景观均衡凹陷到海平面以下。冰消期的冰流受基底地形的控制，冰盖解体后，海水跟随着内陆的冰流（Hardap间冰期）。沉积的沉积直到在冰接地线的泥石流，浊流，泥石流雨和悬浮沉降离开典型的冰撤退序列的沉积物。可能是早二叠世时代的Tses冰川作用紧随间冰期之后。海洋冰盖覆盖该地区，主要是logdement冰碛和层状和层状diamictons沉积在接地线撤退，底部融化的冰架和冰山。在海洋冰盖迅速崩溃后，小冰帽留在山区，在一个暂时的冰前进期间，另一个冰碛层沿着盆地南缘沉积。
The Dwyka Formation, which forms the basal unit of the sedimentary fill in the Kalahari Basin, consists of local reddish basal tillite, an argillaceous sequence of shale, mudstone, siltstone, sandstone, diamictite and carbonate lenses and nodules containing marine fossils, and a well-developedmain tillite. In the Hotazel Valley along the southern margin of the basin an upper tillite is also present. The sequence represents two major ice advances separated by a well-defined interglacial and a minor ice advance confined to the area around the ice-spreading centre.Glacial erosion during maximum glaciation in the late Carboniferous formed a dissected landscape depressed isostatically to below sea level. Ice flow during deglaciation was controlled by the basement topography and upon disintegration of the ice sheet the sea followed the retreating ice inland (Hardap Interglacial). Deposition of lodgement till at the ice grounding line was followed by debris flows, turbidity currents, debris rain and suspension settling leaving sediments typical of an ice retreat sequence. The Tses Glaciation, probably of Early Permian age, followed on the interglacial. A marine ice sheet covered the area and predominantly logdement tills and bedded and laminated diamictons were deposited during grounding line retreat, underside melting of ice shelves and by icebergs respectively. After rapid collapse of the marine ice sheet, small ice caps remained in the mountainous areas and during a temporary ice advance another till horizon was deposited along the southern margin of the basin.