Flood Deposits in Continental and Marine Environments: Character and Significance
Flood Deposits in Continental and Marine Environments: Character and Significance
复制标题
DOI：
10.1306/13271348st613436
复制
发表时间：
2011
期刊：
影响因子：
--
通讯作者：
T. Mulder;E. Chapron
中科院分区：
文献类型：
--
作者：
T. Mulder;E. Chapron
本章以现代环境、露头、沉积物岩心和地震反射剖面为例，重点讨论了地质记录中高闪洪及其沉积（高闪岩）的过程、特征和意义。对于以床载或悬载为主的高岭土，洪水事件的等级曲线是可以预测的，其流量与负荷之间呈幂律关系。由于海水中的再浓缩过程，除了那些被认为是脏的（高沉积物浓度）的河流外，其他河流可能在海底形成长距离的超旋流。特大暴雨洪水一般有气象成因，但特大暴雨洪水也可能因河流汇水区溃决而发生。在某些情况下，灾难性的洪水与地震或火山活动有关。在海洋和湖泊环境中，频繁而强大的高旋流形成了曲流河堤体系和更多的远端盆地扇叶。高辉长岩的特征是在涨潮（渐流）时形成粗化—向上的基层序，在涨潮（渐流）时形成细化—向上的上层序。较低的层序并不总是被保存下来，因此高斑岩可能很难与经典浊积岩区分开来。在矿床底部普遍出现陆源有机碎屑，是高辉长岩的标志。在山脉的冰谷中，大量的碎屑物质通过频繁的超旋流沉积在大的河谷湖泊或峡湾中。在湖泊和海洋环境中，大的超潮洪水有时是灾难性的，有记录表明它与重大的环境变化有关，如大陆的冰川消融或火山-冰川相互作用（jokulhlaup）。
This chapter focuses on the processes, character, and significance of hyperpycnal floods and their deposits (hyperpycnites) in the geologic record based on selected examples from modern environments, outcrops, sediment cores, and seismic reflection profiles. For bed-load- or suspended-load-dominated hyperpycnites, the rating curve of a flood event can be predicted and is represented by a power-law relationship between discharge and load. Because of reconcentration processes in marine waters, rivers other than those considered dirty (high sediment concentration) may form hyperpycnal flows over long distances on the sea floor. Hyperpycnal floods generally have a meteorologic origin, but catastrophic hyperpycnal floods can also occur because of dam outburst in the catchment area of a river. In some cases, catastrophic floods are associated with earthquakes or volcanic activity. Both in marine and lacustrine environments, frequent and powerful hyperpycnal flows develop meandering channel levee systems and more distal basinal fan lobes. Hyperpycnites are characterized by a coarsening-upward basal sequence formed during the rising limb of the flood (waxing flow) and a fining-upward upper sequence formed during the falling limb of the flood (waning flow). The lower sequence is not always preserved, so hyperpycnites may be difficult to distinguish from classical turbidites. The common occurrence of organic debris of continental origin at the base of deposits is an indicator of hyperpycnites. In glacial valleys of mountain ranges, a large amount of clastic material can be deposited in large valley lakes or in fjords by frequent hyperpycnal flows. Both in lacustrine and marine environments, large hyperpycnal floods, which are sometimes catastrophic, are documented in association with significant environmental changes such as deglaciation of the continent or volcano-glacier interactions (jokulhlaup).