Structural Geometry And Kinematics Of Southeast Sichuan Basin:Insights Into Tectonic Relationship With The Western Segment Of XueFeng Mountain Orogenic Belt

The Xuefeng Mountain intracontinental composite tectonic system is the highlight thesis nowadays. The study of the structural characteristics and the structural evolution characteristics of the Sichuan basin southeast structure belt and Hunan-Hubei western structure belt is the base for the study of the Xuefeng Mountain intracontinental composite tectonic system. And the yield of hydrocarbon in Sichuan basin southeast structure belt is very abundance. The research of the structural characteristics and the structural evolution characteristics of Sichuan basin southeast structure belt can guide us to explorate oil and gas.The paper is based on tectonic geology and fault-related folds theory, and uses field geology surveying files, seismic section data and drilling well data. The process is combinating with field survey geology section, surface structural geology section, accurate seismic analysis section to study the structural geometry characteristics of Sichuan basin southeast structure belt and Hunan-Hubei western structure belt. Using the kinematic analysis approach builds the dynamic structural kinematics model for studying the structural evolution characteristics of Sichuan basin southeast structure belt and Hunan-Hubei western structure belt. We try to insight into the tectonic relationship between Sichuan basin southeast structure belt and Hunan-Hubei western structure belt. Meanwhile we study the structural deformation time of Sichuan basin southeast structure belt by the method of apatite fission track.The analysing conclusion of the apatite fission track experimentation: The time when it reaches maximizing deeply buried position and begins into the slowly uplift stage is in 89 Ma at the Early Cretaceous to the beginning Middle Cretaceous. The time when it starts into the fast uplift stage is in about 28 Ma.And the time when the rising velocity starts to low down is in about 20 Ma. Cretaceous and Cenozoic have been in the stage of denudation. Sichuan basin southeast structure belt can be divided into four micro structure belts.There are multi-detachment layers in Sichuan basin southeast structure belt. We have discerned four detachment layers. The base deformation layer is Presinian detachment layer. The lower deformation layer is Cambrian detachment layer. The middle deformation layer is Silurian detachment layer. The upper deformation layer is the lower Triassic Jialingjiang formation detachment layer. The structure shorten is different. The maximum structure shorten is about 1/4, and the minimum structure shorten is about 1/7. The majority is between 1/6 and 1/5. The time of structural deformation of the anticlines is about Late Cretaceous- Paleogene and Neogene. Late Yanshan orogenic movement and Himalayan orogenic movement affect the structural deformation of Sichuan basin southeast structure belt.There are three detachment layers vertically in Hunan-Hubei western structure belt, which are Sinian detachment layer, and two pre-Sinian detachment layers. The time for forming of synclines and anticlines in Hunan-Hubei western structure belt is Caledonian – Hercynian and Indosinian.In Hunan-Hubei western structure belt fold morphological characteristics is narrow syncline and wide anticline. In transition belt fold morphological is the same width of syncline and anticline. In Sichuan basin southeast structure belt fold characteristics is wide syncline and narrow anticline. The fold morphological characteristics of the adjacent three belt is in difference development stage of fold morphological characteristics.The characteristics of detachment deformation in southeast of Sichuan basin are multi-stages and multi- detachment layers. Sichuan basin southeast structure belt and Hunan-Hubei western structure belt is in thrusting nappe tectonic belt of Xuefeng mountain intracontinent orogenic belt. Nappe tectonic slip along detatchment layer by southeast-northwest compression force. Recursive decline deformation is formed from southeast direction to northwest direction.