The Characteristic Of Lithofacies Paleogeography Of The Upper Jurassic Kalazha Formation 1st Member In Shengbei-honglian Area Of Tuha Basin

The research object of the paper is the sand groups of Kalazha Formation ? member in the Taibei Sag of Tuha Basin. Based on the analysis of core, drilling data, logging data and seismic data, making a research for Sedimentology and Lithofacies Palaeogeographic in Shengbei-Honglian area. In this paper, on the basis of well logging curve shape and lithologic features, Kalazha Formation?member subdivides into three groups. Through the application of various of analysis methods, such as Dickinson figure, clastic composition features, debris, heavy mineral and clay mineral composite, shows the provenance of sand bodys came from Bogeda Mountain in the north and Jueluotage Mountain in the sourth without mixed sedimentary area.The typical sedimentary facies marks along target formation have been identified. The grain size analysis is completed. Then well logging curve characteristics and the response of seismic data are studied systematically. Research suggests that the study area develops braided river delta-lake deposits. Based on core facies, logging facies and seismic and granularity analysis data, the single well sedimentary facies integrated histogram of each sand group has carried on the classification of sedimentary facies. Braided river delta front subfacies are the main development of subfacies and microfacies subdivided into underwater distributary channel, distributary bay, mouth bar, far sand dam and so on. Based on multi-port drilling single well sedimentary facies analysis, and then completed the transverse longitudinal even well profile of sedimentary facies in the study area.It means that material supplys full, sand body distribution range is wide and sand ratio is high. Among the three sand groups,the second groups of sand body is the most developed. The sandstone layer thickness is the largest and the most coarse granularity.By analysis of core(more than 20 wells), a variety of soft-sediment deformation structures are identified in the sand groups of Kalazha Formation 1st member of Shengbei-Honglian area. Including liquefaction-induced deformation(sand-veins(wall), Liquefied breccias, Liquefied convolute, ball-and-pillow, homogeneous layer and load deformation), plastic deformation(corrugated Lamination,mound-and-sag, loop bedding, mixed layer), brittle deformation(seismic breccia, echelonment micro-fractures,earthquake ?V? rima). Seismites rock concentrated in 1st or 2ed sand groups, Seismites rock concentrated in one or two sand group. The accumulated thickness of seismites is proportional to the sandstone thickness in the well profile. The sand groups is the special sedimentary response of seismic action. The northern tectonic activities is stronger than the southern, indicating Bogeda Mountain uplifted again in Yanshan Movement ? curtain. Identifying the differences of sedimentary microfacies and cumulative thickness of sand body, seismites control orogenic movement which determined the braided river delta sedimentary system of ?early south late north, steep north slow south?. The authors think that the northern Shengbei area develop steep slope braided river delta and the southern Honglian area is slow slope braided river delta.Based on the study of provenance and depositional system of every sedimentary period, the basin sedimentary model are finally established in Shengbei-Honglian area of Taibei Sag of Tuha Basin. The fine lithofacies palaeogeographic characteristics analysis relys on strata thickness, sand body thickness,sand/ strata ratio and limited boundary of sedimentary subfacies of three sand groups.The result shows that the study area of braided river delta front sedimentary framework without big changes and sedimentary evolution experienced a process of "shrinking lake basin to the expansion".