Research On Upper Paleozoic Tectonic Framework Of Songliao Basin

The Songliao Basin locates to the north of North China Plate, and to the east ofXing’an block. It is considered as a NE-trending fault broad rift basin. It is sandwiched bySiberian plate, North China Plate and the Pacific Plate, constructed by the Jia-Mon block,the ancient Asian ocean and westward subduction of the Pacific Plate strongly. UpperPaleozoic had only been carried out on preliminary geological survey and drilling work,but the study of the Upper Paleozoic basin distribution and structural characteristics isweak. The authors synthesize the latest regional geological data, drilling data and gravityand magnetism data to analyze the Upper Paleozoic distribution characteristics ofSongliao Basin. Based on the interpretation of gravity and magnetic data andseismic-geology section, the authors determine the Songliao Basin Late Paleozoicstratigraphic distribution, attribution analyzes its lithology and the location and activestages of the12skeletal faults. The authors also divided the Upper Paleozoic tectonicunits and summed up their evolution to the study the Upper Paleozoic tectonic frameworkand evolution development of Songliao basin, while providing a new basis for the oil andgas exploration and development.This article summarizes the area late Paleozoic stratigraphic data and compareslogging data inside and outside the actual field surveys and basin to proposed SongliaoBasin Upper Paleozoic sedimentary is a complete whole. Late Paleozoic is mainlyCarboniferous-Permian sedimentary, bottom-up: Carboniferous Tongqigou group (C1t),Luquantun group (C1l) and Mopanshan group (C2m), the Permian Dashizhai group (P2d),Zhesi group (P2z) and upper Permian Linxi (P3l). The lithology is mainly sandstone,mudstone, limestone, silty mudstone, sandstone and volcanic rock debris, both marine,land and sea cross each other, there are continental deposits.Based on geophysical methods, regional gravity, electromagnetic data analysis,basin drilling Upper Paleozoic drilling position and lithology, the authors proposed: Songliao Basin Upper Paleozoic top surface is130,000km2, Upper Paleozoic strata aremainly distributed in the central and southeastern uplift depression, sedimentary is stratain the east, west rift zone contiguous distribution, southeast uplift areas and the westernslope scattered, intrusions is in the west and southeast slope uplift, intrusions are acidicgranite mainly, diorite followed.By collecting basin gravity data, seismic data to determine the location of thefracture and the Songliao Basin skeleton distribution, combined with regional drillingdata, actual field survey, the authors proposed major development of Songliao basin12base skeleton fracture. According to their spatial distribution can be divided into threegroups in different directions: EW, north-east and north-west trend. Based on previousresearch and the results of this study, the authors analyzed the structural features of12base skeleton fracture, tectonic stress environment, the relationship between dynamicmetamorphism, volcanism of times and fracture.Combined with the top surface of the basin of Songliao Basin Upper Paleozoiclithologic distribution and bottom lithology distribution, basement skeletal fracture, theauthors presented Songliao Basin Upper Paleozoic tectonic units classification scheme:west to east as follows. Western depression, whose area is about81,900km2and residualthickness is3~9.5km, distributes along Baicheng-Qiqihar-Nenjiang with unknownthickness granite over top. Central uplift, whose area is about24,700km2and residualthickness is1~2.5km, distributes along Songyuan West-Daqing-Wudalianchi withUpper Paleozoic fold below the bottom. Eastern depression, whose area is about74,700km2and residual thickness is3~11km, distributes along Changchun-Harbin-Tieli,with thick granite over top like western depression, but the thickness should be smallerthan the western depression.Based on the above results of all the studies, combined with tectonic evolution of theNortheast, that the Songliao Basin Upper Paleozoic have “one uplift along with twodepressions” the structural features. Combining seismic interpretation and structuralevolution of the basin with the tectonic revolution of Northeast China, the tectonicevolution of Songliao Basin can be divided into four stages as follows: the first stage, Songnen block and Xing’an block collided roughly along the Heihe–Neijiang-Zhalantunsuture at the end of the Early Carboniferous, resulting in NWW-SEE-trendingcompressional deformation, forming the “one uplift along with two depressions” tectonicframework, the second stage, Jiamusi-Mongolia block and North China plate collidedalong the Xar Moron suture zone in Late Permian, causing formation of the NS-trendingextrusion generated WE-trending relief fold, the third stage, the subduction of westPacific plate beneath the Asian continent in Jurassic, forming the NE-NEE-trendingstrick-slip faults, the fourth stage, the Mesozoic NW-trending brittle fracture deformed.