“源-汇”体系主导下的障壁滨岸沉积体系发育模式——以青海湖倒淌河流域为例

Depositional models of barrier shoreline sedimentary system under guidance of source-to-sink system theory:a case from Daotang river in Qinghai Lake

湖泊的障壁滨岸沉积体系研究一直是湖泊沉积学研究的薄弱点。以青海湖倒淌河流域为例,利用野外露头和遥感影像资料,基于"源-汇"体系的研究思路,识别出青海湖倒淌河流域的"源-汇"体系是由物源区、冲积扇、倒淌河、三角洲和障壁滨岸组成。随着日月山—野牛山一带的隆升,倒淌河流域由原来的古倒淌河和冲积扇沉积逐渐转变成一个相对封闭的"内陆湖"。伴随气候的暖干化和野牛山的进一步隆升,倒淌河发生倒转形成现今的倒淌河-障壁滨岸沉积体系。该体系的形成受控于构造-地貌、物源、水系、气候变化与湖平面的升降。加强对沉积盆地周缘物源区岩性特征、构造作用控制下的湖盆古地貌和古风场的研究,有助于预测陆相断陷湖盆中砂体的有利区。

The research of barrier shoreline sedimentary system of lakes usually plays a weak point of lacustrine sedimentology. Taking Daotang river in Qinghai Lake as an example, based on the outcrop, remote sensing data and ＂source-to-sink＂ method, it is defined that the ＂source-to-sink＂ system is composed of source area, alluvial fan, Daotang river, delta and barrier shore. Along with the uplifting of the Riyue Mountain and the Yeniu Moun- tain, the Daotang river basin was gradually transformed into a relatively closed ＂inland lake＂. With the warm dry climate and the further uplift of Yeniu Mountain, Daotang river overturned and formed a barrier-coastal sedimen- tary system. The formation of the sedimentary system is controlled by tectonic geomorphology, source of the ma- terial, climate change, river system and take level variation. The researches about ancient provenance lithology of sedimentary basins, the lake palaeogeomorphology controlled by tectonic action and palaeowind field are fa- vorable for predicting the sand in the continental rift basin.