Tectonic Evolution Of Paleozoic Key‐unconformities In Tarim Basin

Tarim Basin is the largest composite and superimposed sedimentary basin in the Western of China, having 56 square kilometers. Guiding by the thinking that oil and gas are controlling by Craton’s palaeohigh and palaeoslope, Sinopec have found Marine oil and gas fields on palaeohigh in Tabei area and Tazhong aera, expanding the areaof Marine carbonate oil and gas exploration in Tarim Basin. Therefore to carry out the early Palaeozoic Tarim Basin prototype basin analysis, find out its controlling on source-reservoir-seal, has the important practical significance to speeding up the exploration in Tarim basin Marine oil and gas,.Since Sinan period, Tarim Basin has experienced Caledonian, Hercynian, Indosinian, Yanshan well-developed four tectonic cycle. During the Basin evolution stage, in different tectonic background, caused the different prototype basins, they have different pattern of depression-uplift and geomorphology features. Many times of tectonic reworking to form the multiple unconformity interface and deformation Unconformity formed the structural sequence interface, its distribution, combination and style at the same time, also directly reflects the ancient topography, geomorphology and depression-uplift distribution pattern. This study further traced, T₉⁰, T₇⁴, T₇⁰ and T₆⁰ four unconformity interface, that T₉⁰ unconformity interface formed in extension stage, the rest of the three unconformity interface formed in compression stage, and under the background of tectonic compression, T₇⁴, T₇⁰ and T₆⁰,the three unconformity interfaces formed stratigraphic denudation. This study recovered, T₇⁴, T₇⁰ and T₆⁰, the three unconformity interfaces denudation amount; Survey and based on the studies of former scholars about modern and paleo-water-depth, determined the paleo-water-depth recovery methods and standards, to restore the paleo-water-depth that the early Paleozonic Tarim Basin in different periods. Combined with the tow aspects of the recovery, and the analysis of paleotectonic deformation and recovery, restored the paleotectonic evolution of the four unconformity interfaces. Put forward, since the middle-late ordovician, the early Palaeozoic experienced a strong reform, transformation and tectonic activation three evolutionary stages, obvious migration evolution pattern of depression-uplift, palaeohigh evolution showed, continued, residual, disappear, and reactivation, four patterns.