Early Cretaceous Deltaic Sedimentation of Songliao Basin
In the centra depression of the Songliao Basin, the Early Cretaceous Unit 4 of the Quantou Formation is characterized by shallow, lacustrine deltaic sediments, probably deposited when a meandering river ran into a shallow and broad lake. This type of deltaic sediment is characterized by its well developed subaqueous distributary channels and the lack of river mouth-bar sedimentation. The sub-aqueous channels are mostly media to fine-grained sandstones in fining-upwards sequences. The lower parts of the sandstone channel are commonly cross-bedded and in erosive contact with the underlying lacustrine mudstone, while the upper parts are featured with wave ripple laminations. The shallow lacustrine mudstone characteristic of a color from grey to dark contains fresh water fauna and plant fragments. In contrast, other Cretaceous mudstones of meandering river sequences in the Songliao Basin are always light reddish or brown. The Songliao Basin was expanding outward during the late stage of the Early Cretaceous which is reflected in an overall transgressive sequence: from a meandering river depositional system through a shallow water lacustrine deltaic system to a shallow lake system and then to a deep lake system. In the central depression area of the Songliao Basin, Unit 3 of the Quantou Formation has been interpreted as meandering river sediments, representing a wide and flat fluvial plain, on which a lake was later developed. Controlled by the flat setting, the lake was initially likely to be wide, open and shallow. Uint 4 of the Quantou Formation was deposited as deltaic sediments in this shallow lake setting.
Renchen Xin Tao Guo Chunhui Zhang Xuehui Zhang Yi Zhang
School of Marine Sciences, China University of Geosciences, Beijing 100083, China
国际会议
The 12th Conference of the International Association for Mathematical Geology(第12届国际数学地质大会)
北京
英文
662-664
2007-08-26（万方平台首次上网日期，不代表论文的发表时间）