Discussion on the Model of Braided River Transform to Meandering River: As an example of Toutunhe Formation in Southern Junggar Basin

Key words: 
• braided river /
• meandering river /
• braided to meandering river /
• Toutunhe Formation /
• Junggar Basin /

Abstract: Under the guidance of sequence stratigraphy and sedimentology theory, detailed research on Toutunhe Formation in the Toutunhe outcrop, southern margin of Junggar Basin was carried out  to discuss the model of braided river transform to meandering river. On the basis of the division of sequences and the determination of river-genesis lithofacies, by the field measuring, fine dissecting and sedimentation description and observation, braided river transform to meandering river (braided to meandering river) in Toutunhe Formation was  analyzed and characteristics summarized, and the control factors and depositional setting of braided to meandering river were cleared. In this study, the process of braided to meandering river was controlled by base-level cycle, sedimentary source recharge, gradient and paleoclimate. As the base level rising, sedimentary source recharge decreasing, gradient slowing down and paleoclimate changing to hot-arid gradually, the river type change from braided river to meandering river. Eventually, by the vertical sequence of Toutunhe Formation, the local and regional depositional evolution models are built up.