Geological And Geophysical Quantitative Analysis On Thrust Nappe Structure

The happening and evolution of the regional geological structure are often affected by sometectonic movements with regional characteristics. Regional metamorphism, metallogenicregularities and magmatism are controlled by regional geological structure. The thrust nappestructure developed in the foreland basin of orogenic belt is an important part of regional tectonicunit. The evolution of the thrust nappe structure contributes to the regional characteristics ofgeological structure. The thrust nappe structure under the condition of well cap is a good placefor oil and gas traps, where often shows well signification of oil and gas.The thrust nappe structure is the large extrusion structure that was formed by thecombination of thrust fault and nappes or thrust sheets. It always develops in orogenic forelandsunder the background of extrusion. The thrust nappe structure includes some forms, such as:simple overlap-thrusting system, back-thrusting, ramp-thrusting and wedge-thrusting. Accordingto the relationship between faults and folds, the thrust nappe fault-related folds are classified as:fault-bend folds, fault-propagation folds and detachment folds. Among these structures,fault-bend folds and fault-propagation folds are the typical structures. In this paper, the modelsand morphological characteristics of fault-bend fold and fault-propagation fold are described indetails.in details. Then the geometry quantitative analysis of the thrust nappe structures wascompleted on the building of the geometry relationship of fault-bend fold and fault-propagationfold.Based on the research of predecessors, I comprehensive analyzed the thrust nappe structure,combined with geological and geophysical information. The geological and geophysical processon faults and related folds was successfully simplified using the geometrical relation curve offault-bend folds and fault-propagation folds. Two typical seismic profiles in the Songliao basinwere chosen for case study on thrust nappes. In practical application, the quantitativeinterpretation and comprehensive analysis on thrust nappe was carried out too.Thrust nappe structure is an important target area for the oil and gas exploration, which could form well oil and gas traps. At the same time, it is the high-risk areas with geologicalhazards, such as earthquake. So the comprehensive study of thrust nappe is a work with not onlypractical economic significance, but also important scientific significance.