摘要
A complete sedimentary profile composed mainly of typical lacustrine sediments including beachrock and cut-and-built platform located in the Xishanzui subuplift, Hetao Basin, has been found. The geomorphological and stratigraphic evidence indicates that there was a paleolake with its highest lake up to 1080 m a.s.l. Stratigraphic analysis of the profile indicates that this subuplift experienced an environmental change from a deep lake to a shallow lake and then to non-lake environment (suggested by alluvial/diluvial sediments). Optical dating results support that Xishanzui subuplift was actually covered by a deep water lake, potentially the Megalake"Jilantai-Hetao"at around 65 ka BP when the lake reached its highest level. And no lake level has exceeded the highest level inferred from sedimentary sequence in the profile.