Study On Deformation Tectonic Characteristics Of Soft Sediments

Soft sediment deformation structure refers to the series of structures produced by the deformation of sediment after deposition and before consolidation into rock due to some external physical triggering factors.Therefore,the analysis of soft sediment deformation characteristics,depositional background and triggering mechanism can infer the type of geological events that occurred during deposition.Several field outcrops and a large number of core observations show that a large number of soft sediment deformation structures were developed during the sedimentary period of the extended Ordos Basin Group,ranging from Long 10 to Long 1 in the longitudinal direction and from the edge to the sedimentary center of the lake basin in the plane,but there is no systematic understanding of their types,distribution patterns and triggering mechanisms.Based on the overall analysis,Binchang block was selected as the key anatomical block.Firstly,more than 120 wells in the study area were logged and interpreted through core and logging data.Combined with the core data of 43 core wells,2 types of sedimentary phases,4types of sedimentary subphases and 10 types of sedimentary microphases were classified,5types and 11 types of soft sediment deformation structures were identified,and a detailed and comprehensive analysis of various types of sedimentary microphases and soft sediment deformation was elaborated.Secondly,the spatial distribution pattern of soft sediment deformation is analyzed by using continuous well profile and sedimentary phase plan distribution map.Finally,the formation mechanism of soft sediment deformation structure is refined into three categories and seven influencing factors,which are analyzed and elaborated systematically.The analysis of the paper shows that soft sediment deformation structures are distributed in delta plain,delta front,shallow coastal lake,semi-deep lake and deep lake subphase,and the best development is below the lake shoreline,the triggering factors of soft sediment deformation structures in the study area are physical disturbances such as landslide and liquefaction caused by earthquakes,the steep slope and large space in deep lake area are favorable to the formation and preservation of soft sediment deformation structures,soft sediment deformation The soft sediment deformation structure is both constructive and destructive to the transportation and storage of oil and gas.This study provides sufficient theoretical and factual basis for the morphological characteristics of soft sediment deformation structures and their spatial distribution pattern in the Extension Group of Ordos Basin.