The Structural Characteristics And Depositional Filling In The Sanjiang Basin

Sanjiang basin is located in the Dan hada mountain fold belt and Jia Musi plots of the east of China, the Tian-shan Xin-an fold zone, auspicious black fold system of Zhang-guang-cai ridge fold belt, Jia-mu-si plots with Marina Taiping fold zone, tin Holt fold system that Dan Hatha ridge fold belt of the complex soil and site. We divided the basin into Suibin depression, Fujin uplift and Qianjin depression three first-order tectonic units from west to east. In recent years, along with the oil and gas exploration in the Songliao basin,we transferred Sanjiang basin to Peripheral Basin, and is a important strategic replacement area of Songliao Basin by large area, buried deep, well preserved. We carried out a large number of exploration and research work and obtained great achievements based on the Sanjiang basin in the "Fansanjiang basin", at the same time the point of Sanjiang basin or Fansanjiang basin existence difference, not only in the basin of ages,types, properties, substrate and background.Previous studies have demonstrated that the Sanjiang basin has evolutioned from west to east, In Middle Jurassic, Suibin begins to sink, the deposition of Suibin formation in marine strata by the Juanchuan fracture and Fujin fracture had influenced the basin at the same time. The early Cretaceous,Suibin area was the coal stratum that was the Chengzihe formation.The early Cretaceous period, the area is completely into the continental river-lake deposition stage, and formed the rivers and lakes facies strata that was the Muling formation. Late Early Cretaceous, the area most started to uplift, only near the Zhongfutun area and don’t pull Bielayin mountain area underwent Dongshan group volcano clastic sediments, thereafter most area continued to uplift in Suibin area, which resulting in the area are all in denudation state, and Mesozoic sedimentary history had ending. The late Cretaceous, eastern region of Sanjiang basin began to sink, depositioned thickness larger inland river-lake facies of Houshigou formation, Hailang formation, Qixinghe formation and Yanwo formation. Entering the Cenozoic, Eastern China continental margin entered another stretching rifting cycles, in the northeast of the Heilongjiang province,had depositioned thickness larger coal-bearing clastic rock formation of the Palaeogene and the Yishu graben and Dunmi fracture belt was typical representative. The Palaeogene bn depostion (Baoquanling Group) which in the Suibin depression and Qianjin depression was thickness, played a role in Palaeogene depostion. Late Palaeogene,based on the block lifting,formed unconformity between the The Neogene and the Paleogene.In the Neogene and the Quaternary period, Sanjiang area had integral sinking, western area is widely accepted as the thinner than the thickness of the Fujin formation and Quaternary deposits, and in the eastern depression is relatively thick.In this paper, on the basis of previous studies, we divisioned tectonic layers detailed and undertaked the tectonic evolution of the basin to further analysis.And we analysised the sedimentary filling processof depression, and establish the filling sequence evolution and filling evolution model.1.According to regional research and the studying about the Sanjiang basin, we divided the tectonic evolution of the basin sedimentary filling process into four stages: Late Jurassic compression background and depression, early Cretaceous sedimentary rift sedimentary stage, early Cretaceous, Late Cretaceous depression sedimentary stage of compressional fold and hole filling stage of deposition landform and the inlet of pull-apart basin fill stage.2.The Sanjiang basin during the late Jurassic is a set of marine deposit, in the early Cretaceous basin are gradually by the transitional facies sedimentary transition to fluvial-lacustrine clastic sediments. The late Cretaceous, Sanjiang basin is a set of Red mixed layer and volcano sedimentary, mainly in the ongoing depression. The Department of ancient sedimentary system is alluvial fan-Delta, deep lake and half deep lake-Delta deposition.3.The study shows that in the Sanjiang area, lower Cretaceous Series (including Jurassic) with rich marine fossils unique, Suibin depression, Boli basin, Jixi basin, late Mesozoic strata can be good contrast; the upper Cretaceous to volcano rock and red variegated clastic rocks as the representative, the macro is easy to distinguish; newly drilled qiancanl can well confirmed the qianjin depression havelarge sets of Paleogene strata. Regional geological characteristics indicate that, lower Cretaceous in YiShu, Mudanjiang and Dunmi. Three deep faults that may exist between large rift basin, Paleogene strata are mainly developed in the deep fault.4.The Suibin depression is a single fault half-graben fault depression, characterized by it was faulted in the west and overlapped in the east,it experienced by the end of Cretaceous Yanshan movement strongly modified and formed the present residual basins. Regional depositioned a Mesozoic Upper Jurassic Dongrong group, lower Cretaceous Chengzihe formation, Muling formation layer. And it developed NE and NNW-NW two groups of fracture,the fracture almost for pressure and compression shear fracture. Depression North thrust-nappe than depression Southern more intense; fault activity with multi stage and inheritance.5.Advance the Nongjiang sag and Naolihe sag has "late failure " characteristic, xidalinzi sag was NNE trending faults, from the control and formation thickness relationship has obvious pull-apart characteristics. Through the late Jurassic to early Cretaceous rift, Late Cretaceous denudation, return of Paleogene intense rifting to Neogene depression period of the complex evolution.6.According to the seismic reflection of external geometry internal reflection characteristics top and bottom interface contact geophysical properties in the study area, the seismic facies are identified and classified, were identified five major categories of fiftieen kinds of seismic facies types:mat parallel phase、mat blank phase、phase of the waveform、mat mat random phase、wedge shaped front facies、 wedge shaped waveform phase、wedge-shaped random phase、wedge-shaped divergent phase、filling, filling the former plot parallel phase phase、filling phase of the waveform、filling random phase, prior to the lens and hummocky facies waveform phase.7.Suibin depression, from the late Jurassic to early Cretaceous period, in the sea water invade South and exit process, based in shallow water environment, the deposition of marine mudstone and sandstone, Delta and fan delta in regional development, source direction is mainly from the depression Northwest and southwest, settlement center was in Northwest and southwest.8.Advance Xidalinzi sag in Paleogene development two complete lacustrine level three sequence, to identify5system domains. The lower sequence of lowstand system tract (the group) and transgressive systems tract fan delta-lacustrine depositional system, transgressive system tract (Da-lian-he group) generally reflects the deep-half deep lake environment; the upper sequence of the transgressive system tract have obvious transgressive, highstand system tract development large delta.