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Regional geological structure study was carried out in 2007 with newly completed aeromagnetic and ground gravity surveys in Tibet plateau, China in the scale of 1:1million, covering an area of E78-96 and N28-36. Geological structure frame has now been set up, boundaries of different blocks and deep buried faults were delineated. Sedimentary basins were also classified for strategic oil and gas resource assessment.
Residual gravity anomaly is generated by means of elevation trend correction and isostatic correction to Bouguer anomaly. This anomaly is then used for geological block unit and subunit and deep faults delineation study with its horizontal derivatives and linear enhancement, together with aeromagnetic anomaly study by vertical derivatives, filtering and upward continuations. Seven large blocks and more than ten sub-blocks are clearly revealed. These main blocks are Kekexili, Qiangtang, Cuoqin-bange, Gangtis, and Himalaya form north to south respectively separated by fault belts named Jinsha, Ban-Nu, Xiongba-cuoqin, and Yaluzangbu in turn, and lasa-Biru block in the east part which is separated by Yangbajing-Dangxiong-Qiaze deep and large fault belts in the direction of northeast.
Gravity anomalies of upper Paleozoic and Mesozoic basins above different geological blocks separated form the residual anomaly were applied for depth calculation with the constrains form several seismic profiles, and depth to some Cenozoic basins with Triassic bottom were also determined. Distribution of underground igneous rocks, including intrusive and volcanic, are outlined within basins using magnetic anomaly inversion.
Newly geological mapping data at the scale of 1:250,000 were used in synthetic study on basin boundaries and secondary structures of uplifting and local depressions. Some six large depressions including Yagencuo, Selincuo,yanghu, kekexili, and other foursecondary depression basins are outlined for further oil and gas resource assessment.
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