Geomorphological Characteristics And Sedimentary Models Of The Distributive Fluvial Systems Of The Huangyangquan Fan In The Northwestern Margin Of The Junggar Basin

In this paper,by using Google earth remote sensing earth satellite images and UAV aerial survey images,we carried out a comprehensive and detailed measurement and description of the sedimentary characteristics,channel patterns,and landform features of each zone of the distributive fluvial systems(DFS)of Huangyangquan fan in the northwestern margin of the Junggar Basin in China The continuous changes in the horizontal distribution of the Huangyangquan fan DFS provide a basis for modern sedimentary models for the study of paleogeological sedimentary systems.The DFS coverage area of??the entire Huangyangquan fan is nearly 628 square kilometers,the perimeter of the DFS boundary is 118 kilometers,the source area is 6144 km~2,and the perimeter is 408 km.The plan metric shape of the Huangyangquan fan DFS is a fan with a narrow top and a wide bottom.There are mainly two active river channels on Huangyangquan Fan DFS,namely temporary river channels and seasonal river channels.The seasonal river channels are mainly the Darbute River and the Kelasu River,both of which run through the Huangyangquan Fan DFS.Non-directional migration of seasonal river channels occurs with time,and channel sediments of different periods overlap with each other.Through satellite images and field observations,the Huangyangquan fan DFS is divided into three parts:proximal,middle,and distal based on the morphological characteristics,channel style,and distribution of the DFS.In the proximal part of the DFS of Huangyangquan fan,the development of the fan body is more severe on both sides,so the proximal shape is narrower and longer;as it extends downward,the squeezing effect of the DFS on the left foothill weakens,and the platform on the right extinguishes.The width of the middle DFS of Huangyangquan fan is obviously increased,the slope is decreased,and the degree of channel division is increased,wide and shallow;the proximal of Huangyangquan fan DFS is mainly a single channel model,mainly depositing coarse gravel sediments,mainly black gravel,The roundness is generally from sub-round to sub-prismatic,mainly supported by particles.The middle part of the Huangyangquan fan DFS mainly shows that the width of the river channel decreases,the width of the channel belt increases,but the depth decreases.Compared with the proximal,the sediment size of the middle part becomes smaller as a whole,and the middle to coarse conglomerate is staggered.Compared with the middle part of the DFS end of Huangyangquan fan,the sediment particles are significantly smaller.The sediment is mainly composed of gravel-bearing fine sand,silt and muddy sediments,and contains a small amount of fine gravel.The distal of the DFS extends a short distance in the direction of the source-to-sink.Outside the area where the Kelasu River and the Darbute River flow,most of them are temporary channels mainly dominated by sheetflow.These temporary river channels generally appear at the end of the Huangyangquan fan DFS and in the middle area of??the fan body.They are mainly dominated by sheetflow and are greatly affected by rainfall and other factors.Generally,the river channel does not extend far,the channel is wide and shallow,and the handling capacity is poor.At the same time,some aeolian deposits will also appear in the middle and distal of the DFS of Huangyangquan fan,mainly because the channel to the downstream area has become shallower,the flow has become smaller,the width of the channel has decreased,and some areas beyond the channel have become dry or even formed Sand dunes.The depositional model of Huangyangquan fan is mainly affected by the change of the lake level of Manas Lake,and has been transformed to varying degrees.During the period when Manas Lake was at a high water level,the Huangyang Spring fan developed in the delta deposition mode,and at the low water level,the river fan deposition mode was the main one.The factors that affect the development of DFS are numerous and complex.For DFS of Huangyangquan fan,its development shape is mainly controlled by the source supply,climate,hydrology and structural characteristics.The larger the source area,the greater the supply of sources,and the greater the scale of DFS development.At the same time,the nature of the parent rock in the provenance area also affects the extension length of DFS development to a certain extent.The more stable the parent rock property and the greater the hardness,the larger the development scale of DFS.The climate usually affects the DFS development characteristics,the type of river channel on the DFS and how it ends through rainfall and evaporation.Hydrological characteristics control the scale and shape of DFS development through the size of river flow.The tectonic action determines the size of the tolerable space for DFS development and the slope of the sedimentary area,thus affecting the shape and scale of DFS development.