STUDY ON THE FORMATION OF UNCONFORMATIES AND THE AMOUNT OF ERODED SEDIMENTATION IN TARIM BASIN

On the basis of the analysis of structural characteristics and study of stratigraphy, and by using the principle and approach of wave process analysis, the authors set up the wave process equations in section of typical areas in the Tarim basin. It is shown that the unconformities S/AnS, D 3/AnD 3,T/AnT and J/AnJ which control the formation, migration, accumulation and conservation of oil and gas are of importance in the evolution of the Tarim basin. S/AnS was formed during the late caledonian orogeny and mainly distributed at the Tazhong,Bachu and Tabei Areas. The amount of erosion is great in the areas of Tazhong 18 and Tazhong 5(800～1000m), and becomes smaller to the south and north. T/AnT started at the end of the Permian and behaved extensively in the North of the Tarim basin. The contour of eroded thickness is along NW—SE and becomes smaller from NE to SW(2000m at areas of Ti1 and Cao 2100m at areas of Xuecan1 and Tazhong2. The amount of erosion is 100～600m in the Bachu Area and becomes greater to the NW from SE. J/AnJ is the result of Indochina movement, and the amount of erosion becomes greater from Tazhong to Tadong(200m to 2500m). The amount of erosion in the Bachu uplift becomes greater from SE to NW, and is more than 500～1000m in the most of Tabei uplift.