权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

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

研究了日本西南部奥里萨邦和贾坎德邦二叠系-石炭系Talchir组、奥里萨邦白垩系Athgarh组和中新世Itowo组和Kunimi组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组取得了重要成果。Talchir组揭示了冈瓦纳冰川的退缩和最终消失所控制的沉积和盆地演化。在消冰初期，频繁发生冰川崩塌和山地冰湖破坏，形成高含沙量的泥石流和特大洪水，将大量粗碎屑带入湖中，在盆地边缘形成了陡面扇三角洲。洪泛沉积表现为中等规模、缓起伏、低角度的反沙丘交叉层积，在高速片洪的超临界状态下具有较强的沉积特征。阿斯加尔组沉积于冲积扇环境。在上部扇状沉积中，弥漫性的次水平层状含砾砂岩被解释为片洪沉积。弥漫性分层可能是由洪水中超临界和亚临界流动条件交替主导造成的。扇体以水流作用为主，扇体中下部未形成片状洪水沉积。库尼米组冲积扇沉积保存了超临界洪水沉积，尤其是下扇序列。洪泛流沉积呈平缓起伏、低角度交叉层状。这种分层很可能是超临界流动条件下反沙丘床型的产物。库尼米扇以片洪为主，流、碎屑流为主，尤其在扇下段具有较高的保存潜力。少