Abstract

In the south bank of Qinghai Lake, numerous alluvial fans and coastal deposits have been formed. In terms of their developmental positions and relationships, the denudation system, depositional system, and transportation system consist of source-to-sink systems. Based on the field-investigation evidence and literature survey, it was confirmed that the developmental processes of these “source-to-sink” systems can be divided into three stages: the Early-Late Pleistocene stage, from 39 to 23 ka BP; Late Pleistocene-Early Holocene stage, from 39 to 10.7 ka BP; and modern stage. At the present time, these stages can still be identified as three levels of lake shore terraces. In the Late Pleistocene, the source-to-sink system indicates that the lake level was high, supply of clasts was sufficient, fan deltas had formed, and the lakeside plain continued to develop. At the end of the Late Pleistocene, with the sudden changes in global climate, the climate was dry and cold, and the lake level fell. At this time, the source-to-sink system showed that lake level was relatively low, supply of clasts was reduced, and transportation distance was longer; ancient sediments started to recycle in this system. Until modern times, alluvial fans in the south bank of Qinghai Lake have only rarely been developed, and the supply of clasts is primarily derived from the recirculation of paleo-shore sediments. Meanwhile, a large amount of sandy gravel beaches developed along the lake shore. By studying the multistage source-to-sink systems around modern lakes, the characteristics of the system in lake basins are enriched and provide an important analogy for researches of ancient lake basins.

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