“源-汇”沉积体系主导下的现代风成相发育模式探讨:以青海湖东岸为例

Discussion on Depositional Models of Modern Aeolian Facies under The Guidance of Source-to-Sink System Theory:A case study of East Coast of Qinghai Lake

湖泊滨岸带风成沉积一直是湖泊沉积研究的薄弱点。占据青海湖湖盆面积近五分之一的东岸沙丘为研究现代湖泊滨岸带提供了一个现代沉积实例。随着沉积学的不断发展,研究内容已经从"一元"的传统相模式逐渐过渡为"二元"的"源-汇"体系。以野外地质考察和遥感影像资料为基础,结合文献调研和相关测试分析资料,进行分析。结果表明:团保山前发育有相对广阔的滨岸沉积,指示了青海湖湖水曾经达到山前地带。大面积的滨岸沉积和古沙丘出露水面以及风对山体的吹蚀,为湖东风砂堆积提供了物源基础。干旱-半干旱气候为沙丘的形成提供了有利的气候条件。断陷湖盆的长条形地貌使得风沿着长轴方向吹扬,造成风成堆积物在长轴的一端堆积。高大的团保山/达坂山的山前复杂地貌特征为金字塔沙丘的形成提供了有利的地形条件。西北风产生的波浪和沿岸流作用于沙岛和海晏湾的滨岸带,导致滨浅湖的砂堆积形成沿岸沙坝。随着湖平面的下降,沿岸沙坝出露水面,并逐渐闭合形成障壁岛-泻湖沉积。

The aeolian deposits on the lake shore have always been a weak point in the study of lacus- trine sediments. According to nearly 1/5 of the Qinghai Lake Basin, the east bank sand dunes provide a modem sedimentary example for studying the aeolian sediments of the modem fault basin. With the con- tinuous development of sedimentology, the research content has gradually changed from the traditional model of ＂one element＂ to the source sink system of ＂two elements＂. Based on field geological investiga- tion and remote sensing image data, combined with literature investigation and analysis, the results are obtained by the analysis. The shoreline in the front zone of the Tuanbao Mountain is relatively broad, which shows the Qinghai Lake level had reached the piedmont zone. Large area of the shore deposit and aeolian deposits were eroded by the wind, which provided the sourcebase for sand accumulation. The e- longated landforms of the rift lake basin cause the wind to blow along the long axis, resulting in the ac- cumulation of aeolian deposits at one end of the long axis. The complex geomorphic features in the front of Tuanbao/Daban mountain provide favorable topographic conditions for the formation of the pyramid dunes. Northwest wind generated waves and longshore currents on the island and Haiyan Bay coastal zone, which result in shallow lake sand accumulated along the sand dam. With the decrease of the lake level, the coastal sand bar is exposed to the surface of the water and gradually closed, forming barrier island lagoon deposits.