Gravelly Obstructed Deposits in the Kalazha Formation,Southern Margin of the Junggar Basin
[Objective]The investigation of the genetic kinds and sedimentary properties of barrier deposits has nov-el implications for establishing paleocurbation direction. Gravel barrier deposits can be an essential distinguishing fea-ture for determining the sedimentary microfacies of river channels.[Methods]The sedimentary model and formation mechanism of gravelly sediment were investigated using sedimentary investigations of present gravelly rivers in the Anjihai and TouTunhe Rivers on the southern fringe of the Junggar Basin.[Result]The results revealed that the shape of gravelly barrier sediments could be classified into four types:lenticular deposition,fusiform deposition,ap-proximately circular mafic deposition,and lateral ridges deposition. The lenticular deposit consists of a single large gravel obstacle and a fine-grained sediment ridge behind it. The length of the sediment ridge to the scour region in front of the gravel should be 2∶1,and the long axis of the sediment ridge determines the direction of water flow. Fusi-form deposition consists of a single large gravel acting as a barrier,with the sheet gravel imbricated in front of the bar-rier gravel,forming a sediment ridge. Circular mafic deposition is the main body of numerous gravels that are similar in size to the obstruction,with a "U" shape in the middle supported by fine conglomerate particles. Lateral ridges de-position is the buildup of big gravel on the side or middle of a channel,forming a beach bar that serves as an obstruc-tion to control the river boundary.[Conclusion]The phenomena of developing barrier deposition in the conglomerate of Kalaza Formation in Junggar Basin is finely split,and the identifying mark of gravel barrier deposition is established,providing new fundamental data for river sedimentology.
modern depositsgravelly barrier depositsformation mechanismsKalazha Formation
万方数据
维普
