THE RELATION OF GRAVITY AND AEROMAGNETIC FIELD AND DEEP STRUCTURE IN MIDDLE-NORTHERN LONGMENSHAN MOUNTAINS
Song Hongbiao;Liu Shugen
Based on the correlation analysis of average gravity field and deep seismic sounding data,the depth of Moho discontinuity was estimated in Longmenshan Mountain area. The result shows thatMoho discontinuity is deeper in northwest than in southeast and Longmenshan Mountains are just situ-ated in the steep dipping belt. The isostasy anomaly was calculated and positive anomaly was found inthe area. Upward continuating of aeromagnetic anomaly indicate that Maowen melange has no "root".The depth of the top and bottom of deep magnetic basement were calculated with the technique of aver-age angular raadial energy spectrum. The latter is equivalent to Curie depth. It is considered that uppercrust is pieced together by several smaller blocks and the blocks in west depressed area of Sichuan Basinshow the subduction tendency to Longmenshan Mountains.