Geophysical Field And Deep Tectonic Features Of East China Sea

East China Sea and adjacent regions lie in the margin of East Asian continental and which conclude broad shelf and narrow slope and trench-arc-basin system of the West Pacific Ocean. The study on geologic constitution and regional structure and formation and evolution is significant to understand the interacting of Eurasia Plate and Pacific Plate and global plate structure development. It is also significant to search abundant oil gas and hydrate and maintain maritime sovereignty and reservation and it is also to geological catastrophic forecast and marine environment protection and national economic construction. At the same time, it is also significant to search East Asia continental geological evolution since Indo-Chinese epoch. Its unique geotectonic position and abundant mineral resources make it become geological hotspot between domestic and overseas and it become important region for marine delimitation and dominion and rights and interests dispute between China and Japan.Based on"Geological-Geophysical Map Series of China Seas (1:1,000,000)", we collect petrophysics data of East China Sea and adjacent regions and analyze geophysical field with gravity and magnetic anomaly data and process the data by utilizing upward continuation and wave analysis methods. At the same time calculate deep interfaces which conclude Moho depth and Crust thickness and Magnetic boundary depth and Curie depth. Study areal geological feature and tectonic division according to geological and geophysical integrated interpretation and discuss tectonic evolution.The multiple-height upward continuation processing technology was applied to Bouguer gravity anomaly data from the different area, i.e. upward 20km for Zhe-Min Uplift to Continental Slope, upward 10km for the Okinawa Trough to the Ryukyu Island Arc, and upward 5km for the Ryukyu Trench to the Philippine Sea. Thus the multiple-height gravity anomaly data were obtained and used to retrieve Moho buried depths and analyzed the results show that the characteristics which gravity anomaly contours become smoother and the deep structures become clearer with the increase of the continuation height, which is more meaningful for studying the crust and geologic structure of East China Sea.Wave analysis is the effective tool to decompose of gravity and magnetic field and it not only can extract deep anomaly but also can effectively separate regional anomaly and local gravity. Based on the new Bouguer gravity data of East China Sea and adjacent regions, upward continuation and wave analysis methods are combined in the paper and Bouguer anomaly results of upward 20 km and the 4th order wave approximation are compared and Moho buried depths is calculated in the paper. Analyze and discuss the characteristics of deep structures and anomaly of the 4th order wave result approximation represents Moho and the 4th order detail wave result represents depressions of East China Sea and adjacent regionsMoho buried depth changes between 12 and 34 km and Crust thickness changes between 6 and 34 km and the whole Moho shows concave-convex-concave-convex configuration. Each region is different in East China Sea and adjacent regions. In Continental Shelf region, the crust thickness doesn't change obviously. The thickness of crust begins to thin evidently in Okinawa Trough and middle crust disappears there. In Ryukyu Island Arc region, the crust thickness increases again and upper crust increases most obviously. We deduce it transients from continental crust-transition type crust-oceanic crust from west to east.Magnetic boundary depth contour map reflects the magnetic boundary spread and magnetic boundary of East China Sea are mainly volcanic rock and metamorphic rock and igneous rock. Magnetic boundary depth changes greatly from 4km to 12km in different regions.Curie depth turns into shallow from continental crust to oceanic crust and the whole Curie depth changes from 14km to 29km and contours appear absolute round shape. Curie depth map manifests fluctuant changeable feature rather than singular increasing or descending changeable feature.Gravity and magnetic anomalies of East China Sea manifest NE and NNE spread and are the integrated reflection of fracture and structure. The whole regional tectonic background of East China Sea manifest east-west zoning and south-north blocking feature according to gravity and magnetic anomalies map and Moho and Crust and Magnetic boundary and Curie depth maps. East-west zoning is the main tectonic feature since Indo-Chinese epoch and it is the reflection of Eurasia Plate and Pacific Plate interaction since Mesozoic. South-north blocking is the main tectonic feature before Indo-Chinese epoch and it is the reflection of Chinese Mainland after formation and development of Chinese nuclear and integration and separation of block time after time. There are namely Zhe-min Uplifted Fold Zone and East China Sea Shelf Basin and Tiaoyu Island Magmatic Zone (East China Sea Slope) and Okinawa Trough Basin and Ryukyu Uplifted Fold Zone and Philippine Basin tectonic units.The new gravity and magnetic and seismic and areal geological data are used in the paper and we firstly propose multiple-height upward continuation and mixed processing technology and they obtain excellent result in practice application on the base of analyzing petrophysics and utilizing advanced data processing technology. We calculate deep interfaces which conclude Moho depth and Crust depth and Magnetic boundary depth and Curie depth of East China Sea and we analyze complexly the feature and relation of each interface. We further discuss deep crust structure and it offers new result for investigation and evaluation of oil and gas and natural gas hydrate etc mineral resources.