INVESTIGATION OF THE FORMATION OF HUGE QUATERNARY DEPOSITS ON DADU RIVER NEAR HOUZIYAN HYDROPOWER DAM

The Danba Sopo deposits,a huge Quaternary accumulation of soils and rock blocks,are distributed in the banks of Dadu River near Houziyan hydropower dam.There are 144 Stone Towers made by ancient Tibetan scattered on this deposit.The formation of the huge deposits were considered as glaciation,glacio-fluvium or debris-flow.The paper presents a detailed field investigation of the deposits.The formation of the huge deposits is further examined. It is found that the deposits at left bank are formed mainly through collapsing and sliding of mountainous slopes and the deposits at the right bank are a accumulation of slope collapses mixed with glacio-fluvial and debris-flow deposits.The findings are validated!with drillhole exploration in the deposits.The findings may be valuable to the understanding of the formation of thick deposits at the western Sichuan region and to the protection measures of the Stone Towers.