Chuyu¹ ,Zhang fenglong² ,Yang xiangkui¹ ,Guo hongbin²

1 Hei Long-jiang institute of Geological Survey,Hei Long-jiang province,Harbin city,150036,China；

2 No.904 Hydro-geology and Engineering Geology team, Hei Long-jiang province ,Shuang-cheng city , 150111,China

Abstract: The northeast plain is composed of Songliao Plain, Three River plain, Xingkai Lake Plain and Hailaer High Plain. Through analyzing petrofacies of these plains, We found that the ancient hydrology net had changed sever times in this four plains in 3.00 Ma.

Key words: P. R., 3.00 Ma; the northeast plain, Ancient hydrology net, changed

1 In 3.00-2.5ma,bp

The four plains composed inland separate embryonic hydrographic net .A big lowland near Da^,an on the Songliao Plain .Ancient Nen River ran along Lindian and Taikang into it and ancient west Liao River ran along Tongliao and Qian^’an into it(Fig.1) .Other branch rivers had not formed.

There were only three ancient lowlands in Three River Plain. The ancient Songhua River was a small

river and ran into a big lowland(Fig.2),and its branch river had not formed. The Xingkai Lank Plain had deposited 30-50m alluvial deposit near the Songacha River and there was only one big waters, the Beier Lake, on the Hailaer High Plain .

In conclusion, in this epoch the ancient rivers on these plains were short, and the branch rivers were few. So inland separate embryonic hydrographic nets were formed .

2 In 2.5-1.00 ma ,bp

The ancient hydrographic nets on these four plains were still separated. Except the ancient hydrographic net on the Songliao Plain ran from the south to the north and then into the sea, other three plains were still inland hydrographic nets.

In 2.5-1.00 Ma ,BP, the ancient Shonghua River maturated, but was still inland hydrographic net. And there was a big lake on the plain. The ancient Nen River maturated and formed a big lake near Kangtai,Da^,an and Tongliao.Its south segment ran through Zhangwu into Xia Liao River and then into the sea .Its north segment ran through Sunwu Graben and joint with the Jieya River in Russia ,so it formed a through north-south hydrographic net. There were two big lakes and rivers which ran into the lakes in Beier Lake and Handagai on the Hailaer High Plain, so these formed another inland hydrographic net. There were two big lakes and rivers which ran into the lakes on the Xingkai Lake Plain(Fig.3) ,and it also an inland hydrographic net.

3 In 1.00-0.70 ma ,bp

There was a very impetuous crustal movement in northeast China. The effect of this crustal movement was very dip, because it changed the pattern of mountains and rivers. Because of this movement mountains around the four plains lifted fast. Especially the north segment quickly lifted, so the road was blocked, through which Jieya River ran the Sunwu Graben to Songliao Plain .The mountain north of Xia Liao River was lifted ,so the road the Songliao hydrographic net ran south was blocked. So the Songliao hydrographic net was an inland hydrographic net in this short time. It is obvious that the dividing ridge of the Songliao Plain was the mountains north of the Liao River Plain .

In 0.7 Ma,BP, the ancient Songhua River ran along the Yiyin Graben through the Yilan Canyon ,and the ancient Heilong River ran through the Jiayin Canyon . The two river all ran into the Three River Plain. At this time ,the Three River Plain and Songliao Plain ancient hydrographic nets connected(Fig.4).Except the Hailaer High Plain and Xingkai Lake Plain hydrographic nets ,the ancient Heilong River hydrographic net had all transfixed. After jointed

with the big branch rivers ,it ran to the north in the Fuyuan on the Three River Plain ,through Russia into the sea .It changed into a outward hydrographic net.

Then why we say the ancient Heilong River changed into a outward hydrographic net in 0.7Ma ,BP?

The author analyzed the ancient geography of the ancient Songhua River and Heilong River petrofacies on the Three River Plain（Fig.5） ,and found that the deposit of this time was different from the underlie Quaternary deposit. Its grain size was bigger and the containing water was more .The geophysical exploration also proved the electrical resistivity was 1-3 times higher than the underlie stratum. These all proved that the flux was very big. It is no other than the hydrographic net ran through the Yilan Canyon and Jiayin Canyon and jointed with upper course hydrographic nets .The chronology proved this series deposit strata was in 0.7 Ma,BP. Otherwise there was no other big lake on the Three Lake Plain and the lake was dead in early Pleistocene epoch. This also proved the Heilong River was outward.

So the Heilong River was outward from 0.7 Ma,BP.

4 in 0.7-0.02 Ma,BP

The ancient Heilong River jointed with other hydrographic nets on the Hailaer High Plian ,Songnen Plain ,Three River Plain and Xingkai Lake Plain. These formed the Heilong River hydrographic net ran outward into the sea. The ancient Xia Liao River captured the west and east Liao River and ran south into the sea .

In the mid Pleistocene epoch ,the ancient Heilong River was confined of the change of the ancient climate and the crust movement. In the interglacial period and the stratum fall epoch, the flux change mach, so the mid Pleistocene epoch was a prosperous time of the two lakes. The Songliao Plain, Three Plain and Xingkai Lake Plain all fell down. It caused the deposit range reached the posterior border of the nowadays platform. The lake was at the height of the development. The ancient Three River Lake move south to the area around Baoqing and Shuangyanshan. There were big lakes near the Jixian ,Tangyuan ,and Heli. The ancient Xingkai Lake reached the edge of the platform and the Muling River divided into two branch into it. The Songliao Big Lake extended to the east high plain edge. The Hailaer High plain and Hulun lake formed and these ware joint with Beier Lake. When the glacial epoch came , the lake holded back or dead and the river developed. The pan-shaped plain was formed front of the mountain.

In the 0.2 Ma,BP, there was another crust movement in the northeast China. This movement was not as impetuous as the early Pleistocene epoch’s. But to the northeast it was very important. In this movement the edge of the plain keeping lifting ,which caused the mountain stream formed and it cutting the valley deeply. Big changed happened in the Songliao Plain. Its east part, the high plain, lifted quickly and stopped depositing. Its west part, the low plain, went on lowing and into river and lake faces. There is an explanation that the high plain lifted had obvious differently, so the ancient Liao River changed. In the beging the palace of origin of the east Liao River was Hada mountain. But in mid Pleistocene epoch it was south-north, and ran into Songnen Plain jointed with the Songhua River. There was an obvious watershed between it and the second Songhua river’s branch ,yitong river. This watershed in stream source area,the Dahu mountain to the Kaoshan town, and though the Dahei mountain then into the Songnen High Plain. In the late mid Pleistocene epoch the Songliao big lake was in the height developing period ,so the high plain was submerged by the lake. And so the second Songhua River ,Yitong River and east Liao River ran into the Songliao big lake on the edge of the high plain. In the mid Pleistocene epoch and the beging of late Pleistocene epoch the high plain between Huaide and Yongjiu town lifted quickly, and the road the east Liao River ran to the north was blocked. So the ran west like an arc, round the mole track. And at this time the Liao River’s head erosion was intensive, cutting through the east Liao mountain and captured the east Liao River. So it ran south to the sea. So it proved that the watershed between the east Liao River and Songhua River was formed between the mid Pleistocene epoch and the beging of late Pleistocene epoch, in 0.2Ma,BP.

The scientist of geonomy have paid much attention to the space-time locating of the watershed Between Songhua River and Liao River. Especially where is watershed between the west Liao River and Nen River on the low plain, and when it formed. And there is still not last words. But the author found that there was on watershed on the low plain, through the geologic investigation of the desert environment .

Science the mid Pleistocene epoch the west Liao River ran into Songnen low plain ,and became a branch of the Nen River. Then when and why the west Liao lake diverted east into the Xia Liao River The author considered that it because of the change of the ancient climate and ancient hydrological environment. In 0.035-0.2 Ma ,BP, in the interglacial period of the last glacial epoch, the ancient was relatively warm and wet, and rainfall grew sharply. The flood of the Nen River and Songhua River happened frequently. Through the analysis of the deposit on the low plain in this period, the low plain from Qiqihaer south to Tongliao was submerged by the flood, formed the biggest lake in the end of late Pleistocene epoch. Because of the flood form the east ,after the west Liao River ran into the Liao province, the two water jointed. It not only caused the water height lifted ,but also caused the west Liao River ran slowly and diverted east to jointed with east Liao River, then ran south into the sea. At the same time ,the two water jointing caused the hydroenergy became low. So the sand its carried deposited, and formed a very big lacustrine and fluvial natural banks. These natural banks distributed widely on the west Liao Plain Ke’erqin area. It also was called ke’erqin dene, about 40369 km².

The shadows of this area’s natural banks were very clarity in the satellite photo maps, and being with downright regularity. The natural banks that formed by lake present in arc along the south bank of Song Liao big lake, and from Ke Zuo Zhongqi to Chang Ling, to Tong Yu area have more than 10 lakes forming into natural banks with grandness scenery. The level of the natural banks are commonly higher than the on site’s base level 15-20m, width 4-6Km, length 80-250 Km. The billabongs among the banks are ponds and meadows composing with matter of

lake, and lower with fine sand, silt; higher with shallow layer of silty sandy soil (so the soil is easy to form into dene when it’s vegetation is destroyed).

The natural banks that formed by lake parallel distribute along the river, and the natural banks that heading northwest orientation distribute in the northeast bank, such as Cha Ganmulun River, Wu Erjiren River, Hu Huer River. The natural banks are 15-25Km length, 1-2Km width, 15-20m high. The natural banks that heading southwest orientation mainly distribute in the east bank, such as Gu Erguli River, Ge Shaguole River. The natural banks are 15-25Km length, 1-2Km width, 15-16m high. The natural banks that heading to east and west orientation mainly distribute in the south bank, such as Xi Lamulun River. The natural banks are 300Km length, 10-20Km width, 15-20m high.

In the 20,000 years, the geologic climate became cold and dry, and especially in the prevailing glacial epoch in 18,000 to 15,000 years the geologic climate achieved the coldest period. The ancient Song Liao big lake quickly died out, at that time, the water distribution homologized reducing, so it had no ability any longer to break through natural banks that blocking at its forward road and to inflood into Song Nen Plain. Thus, West Liao River viz. turned into permanent anabranch of Xia Liao River. It is obvious that in 20,000 years should be the period that the West Liao River divagated to east and rushed down and converged at Xia Liao River.

At the same time, the Hailaer high plain from west to east and the Xing Kai Lake plain from southwest to northeast tilted raise, which led the water of the Hulunbeier Lake and Xing Kai Lake rushed out and became the Heilong River water system. Thus, Heilong River water system connected the water systems four plains and came into being a uniform rushed out water system(Fig.6).