Thesis Guide For Postgraduates Of Northwest University

The anisotropy of magnetic susceptibility as a analysis method of the structural deformation of rocks,There is a good correlation between three main axis ofanisotropy of magnetic susceptibility and stress ellipsoid.The anisotropy of magnetic susceptibility is widely applied to regional tectonic deformation.At present,a lot of magnetic fabric study focused on the single stress direction,while the superposition area of study is less.Previous superimposed stress have been found,in the second direction,the direction of magnetic lineation deflection phenomenon happens.South Dabashan foreland structural belt located in the Yangtze block on the northwest edge the magnetic lineation deflection phenomenon was found by scholars.But for the distribution relations and the law of the magnetic lineation and tectonic superposition stress direction is still not clear.So in this paper,we carried out the magnetic fabric study in here and obtained the certain understanding:a.Discussed the stress variation from the orogenic belt to the foreland basin.In the study area,sampling in the direction perpendicular to the south dabashan mountain arc,Judging the change rule of the section Tongjiang-Zhenba of south dabashan mountain by magnetic fabric characteristics.Through sample test results,a total of five different kinds of magnetic fabric types has found:sedimentary magnetic fabric,initial deformation magnetic fabric,pencil magnetic fabric,weak cleavage magnetic fabric and strong cleavage magnetic fabric.K1 is distributed clutter in the level,concentrated distribution gradually,until vertical to the level from the foreland basin to the orogenic belt,and K3,the first,is vertical level,gradually transited to a zonal distribution,finally parallel to level.Illustrating that near the Tongjiang area is undeformed magnetic fabric,to Zhenba town is the initial deformation and pencil magnetic fabric in order,near orogenic belt is cleavage magnetic fabric.Indicating the stress suffered largest in the study area is in the north east,and to basin inside recede.b.Preliminarily explored magnetic fabric in the South Dabashan Mountain and Micangshan tectonic belt overlay deformation zone.According to the arrangement of magnetic lineation of Micangshan area and South Dabashan mountain area,Get the maximum principal compressive stress direction of Micangshan is about 131°-145°,and South Dabashan Mountain is 245°.Arrangement of the magnetic lineation is about N-S in the superposition region.Preliminary results show that magnetic lineation direction is close to the resultant force direction of the two different stress direction in superposition deformation zone.The same,magnetic lineation direction is close to the resultant force direction of South Dabashan mountain and High and Steep structures.