Abstract:

HQ-13 Line is the first comprehensive geophysical-geological sectionstretched deeply to the bottom of the lithosphere in the Lower Yangzi Reaches.The section, over 500km long, starts form Lingbi of Anhui Province in then orthwest to Fengxian of Shanghai in the southeast. Gravity survey, aeromag-netic survey, crustal seismic sounding, crustal seismic reflection, geo-electromagnetic sounding, absorbed hydrocarbon, soil mercury measurement and ground geological survey have been carried out on the section. They have revealed the structural features of the crust and mantle of this area which have"eight sides", "seven layers" in vertical and "four blocks" in horizontal.Twelve major geological achievements have been obtained. Some of the achieve-ments belong to basic geological theory, e. g., multiple glides. multi-layerbalanced adjustment, the evolution sequence of depression-uplift exchange instructural layers in vertical: confirming the Moho to be transition layer ofseveral thousand meters thick, the multicontrol of deep-seated geologicalfactors over structural evolution of basins, etc…… Some are great regionalgeological questions, including the confirmation of both deeper and shal-olwer metamorphic crystal basements,the discovery of the Shuanggou nappe beltas the boundary between the North China Platform and the Yangzi Para-platform. Some are related directly to hydrocarbon exploration, such as the thickness, buried depth and internal structural features of Paleozoic and Me-sozoic marine sediments, the heterogeneity of geothermal fields in verticaland horizontal directions etc..