The mixed sedimentation is a new research field for the sedimentology.The mixed sedimentation develops extensively in the Lower Ordovician of Sichuan Basin.This paper studies the mixed sedimentation in this area based on the regional geological data,the well logging data,and the observation of well cores and 3conclusions are obtained as follows.(1)The mixed sedimentation rocks spread in the southwest,middle of the area.In the rest of the area,lithofacies sequences are characterized by the interbeded mixed d...