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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

在奥里萨邦和贾坎德邦的二叠纪-石炭纪 Talchir 组、奥里萨邦白垩纪 Athgarh 组以及日本西南部中新世 Itowo 和 Kunimi 组中，研究了超临界洪水流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组获得了重要成果。Talchir组揭示了冈瓦纳冰川退缩和最终消失控制的沉积和盆地演化。冰消期初期，冰川崩塌和山地冰湖溃决频繁发生，形成高泥石流和特大洪水，将大量粗碎屑带入湖中，在盆地边缘形成陡面扇三角洲。洪水流沉积物显示出中到大规模、平缓起伏、低角度的反沙丘起源的交叉层理，并证明了高速席状洪水超临界状态下的沉积作用。Athgarh 组沉积在冲积扇环境中。在上部扇沉积物中，广泛的近水平层状卵石砂岩被解释为席状洪水沉积物。扩散分层可能是由于洪水流中超临界和欠临界流动条件交替占主导地位造成的。扇区以水流过程为主,扇区中下部未保存席状洪水沉积物。国见组冲积扇沉积物保存有超临界洪水沉积物,尤其是扇下部序列。洪水沉积物表现出平缓起伏的低角度交叉层理。这种分层很可能是超临界流条件下反沙丘床形态的产物。在国见扇中，与水流和泥石流过程相比，片状洪水占主导地位，超临界洪水流沉积物具有较高的保存潜力，特别是在扇下段。较少的