Water system collection

Six water systems originating from the periphery of the basin converge to the center of the depression, and the north and south rivers meet and flow eastward out of the basin in dry season. During the sedimentary period of the 3rd and 4th members of Quan Quan, there were six water systems originating from the periphery of the basin (Figure 1-3).

Nehe-Yi 'an River system: It enters the basin from near Nehe River, forms an alluvial fan at the edge of the basin, flows due south, and divides into two tributaries near Lin Dian. The west branch runs south along the Shawlink-Aogula fault zone and flows into the river from Baicheng. The east tributary flows to Daqing placanticline and is divided into several tributaries, which has an impact on Sanzhao sag.

Baiquan-Qinggang River System: It enters the basin from Baiquan and Hailun, forming an alluvial fan. Then the river flows from Mingshui area to southwest and north of Anda, and is divided into three tributaries. Two tributaries in the west flow into Sanzhao sag from Anda and Songzhan respectively, and one in the east flows into Zhaodong and then continues to flow eastward. This water system mainly controls the sedimentation in the northern part of Sanzhao sag.

Huaide-Changchun River System: It flows into the basin from Changchun-Huaide direction, flows northward, and begins to branch off near Guo Qian, which mainly controls the deposition of Maoxing, Zhaoyuan, Zhaozhou, Xujiaweizi, Changchun Ridge, Chaoyanggou and southern Yushu Forest in the southern part of Sanzhao Depression.

Baokang River System: The river flows northeast after flowing into the basin from the self-protection direction, which mainly controls the deposition in the area east of Gan 'an Uplift. After the marginal depression was filled, it crossed the uplift in a short time and flowed into Baicheng water system and Huaide-Changchun water system in the north and east respectively.

Baicheng and Yingtai water systems: they are a series of scattered short rivers, and the ancient water flows from Baicheng to the east, affecting Da 'an and the south of placanticline.

Qiqihar Water System: Originating in Qiqihar, it flows to the southeast and joins the Nehe Water System in the south of Taikang.

Among the six major water systems, Nehe-Yi 'an, Baiquan-Cyclobalanopsis and Huaide-Changchun are three water systems with a long history, and they are the dominant water systems that control the sedimentation of Songliao Basin in this period. During the flood period, the lake expanded, and the rivers outside the basin entered the lake, forming delta deposits. With the progradation of the delta, the lake was filled up and disappeared, and rivers from all directions around the basin merged in the center of the depression and turned around and flowed out of the basin eastward.