Meso-Cenozoic Structural Features And Evolution Of Laoting Depression And Its Surrounding Areas

Laoting depression and its surrounding areas located in the middle of Bohai Bay Basin is a half graben-like basin, conrolled by the North- East Luannan fault and North-West-West Laoting fault, spreading nearly East-South. Laoting depression is affected by basement morphology and deformation characteristics of cap rock , profile arrangement along structural trend being very different. From west to east it can be divided into Western, Central and Eastern areas, among which Western area is half-graben sedimentary basinLaoting depression and its surrounding areas is Mesozoic and Cenozoic extensional rift basin, Extension is the form of tectonic deformation in Mesozoic and Cenozoic. The aim of the thesis is to make clear Mesozoic and Cenozoic structural characteristics in Laoting Depression and its surrounding areas, which provide a basis for further exploration. Based on the result of detailed seismic interpretation, the thesis emphasizes the analysis on structural characteristics of Meso-cenozoic basin and probes into tectonic evolution to provide a basis for researching favorable traps.According to the situation of fault development and the time of continuing activity , the faults can be divided into four types including longevity, presenility , epigenotype faults. Profile patterns of the fault can be divided into horst and graben, "y"-shape, broom-shape and step-shape. The plane combination of the fault, mainly the plane models of combination of Luan River fault and its induced fault, is mostly spindle-like.Placing more stress on exploration and evaluation of Mesozoic strata , considering the characteristics of basin-forming period and deformation characteristics in the study area, and regarding important fault as the boundary of the tectonic units, the study area can be divided from north to south into Jianggezhuang Uplift, West-laoting sub-sag, East-Laoting sub-sag, Matouying uplift and Shijiutuo sag.According to formation and development features of the fault, through the analysis of the tectonic evolution history, Laoting depression experienced a period of cratonic basin, Mesozoic extensional rift basin, Paleogene extensional faulted depression and Neogene extension of the depression since the Paleozoic.The structural types in the study area are divided into block fault and anticline. On the basis of the order and the arrangement of the faults, The types of block fault include cisoid fault, inversed fault, graben and horst. The formation of the anticline is mainly associated with the activity of faults and differential compaction on the buried hill, consisting, in the study area, of drag structure, reversed drag structure and drape structure.