Origin of the Quaternary Muddy Gravel Deposits in Huanggushan of Jinshi City,Hunan Province

There is a sequence of muddy gravel deposits at Huanggushan,Jinshi City.This sequence was once considered as moraine deposits.The authors of this paper re-surveyed the lithology,compositions and lateral change of the deposits,and studied the fabric characteristics and surface textures of the gravels.On the outcrop of the muddy gravel deposits,the gravels from the lower section are smaller,which suggest that the lower section is probably the main body of debris flow deposits,while the upper section represents surface float-gravel deposit. The gravels show certain degrees of orientation.There isn't typical moraine gravel with scrape surface in the deposits.The so-called"glacial striae"on some gravel were formed under differential weathering and abrasion along stratification.The concave-surface gravels show abrasion and fracture appearance.Some gravels have cracks but are not broken,which is caused probably by strike,rotation and staggering in debris flow.From north to south,the muddy gravel deposits(viscous debris flow deposits) change into non-viscous debris flow deposits within short distance with grain size becoming smaller and roundness higher.There are small low-rise hills to the west of the deposits but there aren't high-elevation mountains around.All evidences indicate that the muddy gravel deposits in Huanggushan,Jinshi Hunan are of debris flow deposits and not moraines.This cognition provides new information for the studies of Quaternary glaciations in Hunan and east China.