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Supercritical flood-flow sedimentation and its preservation potential in geologic records

超临界洪水流沉积及其地质记录保存潜力

基本信息

批准号：
15540439
负责人：
MAEJIMA Wataru
金额：
$ 2.11万
依托单位：
Osaka City University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2006
项目状态：
已结题

项目摘要

Supercritical flood-flow sedimentation and its preservation potential in geologic records were studied in the Permo-Carboniferous Talchir Formation of Orissa and Jharkhand, Cretaceous Athgarh Formation of Orissa and Miocene Itowo and Kunimi formations in southwestern Japan. Among them, the important results were obtained from the Talchir Formation in Orissa, the Athgarh Formation and Kunimi Formation.The Talchir Formation reveals sedimentation and basin evolution controlled by recession and final disappearance of the Gondwana glacier. In the initial stage of deglaciation, a collapse of a glacier and a failure of montane glacial lakes frequently occurred and gave rise to generation of a highly sediment- laden debris flow and a catastrophic flood, which brought abundant coarse clastics into the lake and built a steep-faced fan delta on the basin margin. The flood-flow deposits show middle-to large-scale, gently undulating, low-angle cross stratification of an antidune origin and demonstr … More ate sedimentation in the supercritical regime of high velocity sheet floods.The Athgarh Formation was deposited in an alluvial fan environment. Within the upper fan deposits, diffusely subhorizontally stratified pebbly sandstones are interpreted as sheet flood deposits. Diffuse stratification was possibly resulted from alternate dominance of a super- and undercritical flow conditions within a flood flow. The fan was dominated by stream flow processes and the sheet flood deposits were not preserved in the middle and lower fan areas.The alluvial fan deposits in the Kunimi Formation preserve the supercritical flood flow deposits especially in the lower fan succession. The flood flow deposits show gently undulating, low-angle cross stratification. Such stratification is most possibly the product of an antidune bedform under a supercritical flow condition. In the Kunimi fan, sheet floods were dominated compared with stream flow and debris flow processes and the supercritical flood-flow deposits had high preservation potential especially in the lower fan segment. Less

研究了奥里萨邦和贾坎德的石炭-二叠纪Talchir组、奥里萨邦的白垩纪Athgarh组以及日本西南部中新世Itowo组和Kunimi组的超临界洪水沉积及其在地质记录中的保存潜力。其中，奥里萨邦Talchir组、Athgarh组和Kunimi组的研究取得了重要成果，Talchir组揭示了冈瓦纳冰川退缩和最终消失所控制的沉积作用和盆地演化。在冰消初期，冰川崩塌和山地冰湖溃决频繁发生，并导致高含沙泥石流和特大洪水的产生，将大量粗碎屑带入冰湖，在盆地边缘形成陡面扇三角洲。洪水流沉积物显示出中等规模到大型的、平缓起伏的、低角度的反沙丘成因的交错层理， ...更多信息在高速片状洪水的超临界状态下的晚期沉积。Athgarh组沉积于冲积扇环境中。在上部扇沉积物中，扩散的近水平层状含砾砂岩被解释为席状洪水沉积物。扩散层结可能是由于洪水中超临界和亚临界水流交替占主导地位造成的。扇体以流水作用为主，中、下扇区不保存席状洪水沉积，特别是下扇层序中，Kunimi组冲积扇沉积保存了超临界洪水沉积。洪水流沉积物显示出平缓起伏的低角度交叉分层。这种分层很可能是在超临界流动条件下反沙丘底形的产物。在Kunimi扇，片洪水占主导地位相比，溪流和泥石流过程和超临界洪水流沉积物具有较高的保存潜力，特别是在较低的扇段。少