Supercritical flow sedimentation of flash floods and its preservation potential in rock records

对几个沉积序列的研究表明，超临界流沉积记录在山洪暴发沉积中保存良好。超临界流体沉积物的内部层结形式表现出很大的变异性，特别是在其幅度/波长比上。这种层结的变异性归因于反沙丘底形的形态差异。水槽试验表明，反沙丘的振幅/波长比与水流深度有关，水流深度越浅，振幅/波长比越高。通过对新近系库尼米组河道内洪水沉积和片状洪水沉积内部层结形式的对比，发现后者的波幅/波长比值始终大于前者。这一结果与水槽试验结果相吻合。

Studies of several sedimentary successions revealed that records of supercritical flow sedimentation are well preserved in flash flood deposits. The form of internal stratification of supercritical flow deposits shows wide variability, especially in its amplitude/wave length ratio. This variability in stratification is attributed to the morphological differences in antidune bedforms. The flume experiments show the amplitude/wave length ratio of antidunes is dependent with flow depths; shallower the flow depth, higher the amplitude/wave length ratio. Comparison of forms of internal stratification of in-channel flood deposits and sheet flood deposits in the Neogene Kunimi Formation revealed that the values of amplitude/wave length ratio of anidunes in the latter are consistently larger than the values in the former. This result is compatible with the results of the flume experiments.