Geological Features Of Main Faults And Three-dimensional Geological Model In Eastern Area Of Liaoning Province

The fault is that rock formations of crustal surface along the fracture surface have apparent displacement. The fault often constitutes the regional geological framework, which not only controls the tectonic evolution of the regional geological, but also affects and controls the regional metallogeny. The basin-controlling fault plays an important role in the evolution and the formation of the basin.The fault develops very well in workspace of Liaodong area, not only controls the tectonic framework in the study area, but also controls the magma activities, mineralization and the formation and evolution of Mesozoic fault-depressed basins in this region. In this area, main fault is in north-north-east to north-east direction, and two groups of faults that are nearly east-west and north-west develop. The fault that runs north-north-east to north-east is the main structure in the research area, which mainly formed in the Mesozoic era, and is caused by the earth’s crust tectonic deformation of the ancient Pacific plate diving to the Eurasian plate. In the Early Cretaceous strata, the crustal activities reached the peak, the eastern China under the action of a north-south couple producing east-west pressure movement, the north-north-east strike-slip faults and north-west to north-north-west transtensional faults. In the past study of this region, geological data, drilling data, remote sensing image information and seismic profiles interpretation were used to study the fault. The research generally is through formation time and tectonic evolution of faults. The deep geological research and three-dimensional geological modeling have not yet been carried out on the fault in the region, which restricted the comprehensive understanding of fault characteristics on a certain extent. The study on deep geological characteristics of the fault can get more detailed and reliable information of deep geological structure, which benefits to find out the deep occurrence, spatial distribution and three-dimensional geometry characteristic of the fault, the relationship with other geological bodies, formation and evolution history, etc.On the basis of existing geological, geophysical research work, this study carried out geological data collection and sorting, wild geological research, figure-cut sections, non-seismic geophysical inversion etc, comprehensive research method in the study area on deep geological characteristics of the fault, and used block geological modeling method to build three-dimensional geological framework of the main fault in Liaodong area. The main achievements are as follows:(1) On the basis of regional geological and geophysical research, high precision gravity-magnetic and MT interpretation of backbone profiles, revealed deep geological characteristics of the main fault in Liaodong area, used block geological modeling method to build three-dimensional geological model of the main fault in the study area.(2) Hanling-Pianling fault zone has an obvious effect to the division of regional gravity-magnetic field. According to the result of aeromagnetic anomalies upward continuation, it is considered that the fault zone is a sinistral strike-slip fault, and its biggest leap distance is about 53 km. According to Bouguer gravity anomalies upward continuation, there is a shallower cutting depth with Hanling-Pianling fault zone. It mostly developed in the sedimentary cover. The processing and interpretation results of four integrated geophysical profiles show that the occurrences of Hanling-Pianling fault are various in different locations, the deep tendency of the western fault is N, the apparent dip is about 65°; while the deep fault in the middle tends to NW, its apparent dip is about 60°; the north of the deep fault tends to NW and SE, the change of apparent dip is large about 35°~50° according to its swing feature.(3) In eastern Liaoning Province, the north-west Haicheng-Xinmucheng-Xiuyan fault zone tends to NE and SW with the characteristic of oscillation in east, whose apparent dip is about 60 °~75 °.(4) In eastern Liaoning Province, the west of nearly east-west Haicheng-Caohekou fault zone tendency angle change is big, whose dip from 70 ° decreases to about 25 °. The occurrence local secondary faults is almost vertical.(5) In this region, faults that run north-east to north-north-east generally have a si nistral strike-slip phenomenon and mark.