Characteristics and Formation Mechanism of Composite Flower Structures in Northern Slope of Tazhong Uplift, Tarim Basin

Han Xiaoying; Tang Liangjie; Cao Zicheng; Wei Huadong; Fu Chenyang

Abstract：Developmental stages and mechanisms of the strike-slip faults on the northern slope of the Tarim basin remains controversial despite many studies.However,a more detailed study of the strike-slip faults in the area is possible due to the availability of high-quality 3D seismic data now.It is found that a series of strike-slip faults,which cut through the basement strata and straight up to the Middle Devonian strata,developed in the study area based on detailed 3D seismic interpretations.On the 3D seismic profiles,the strike-slip fault shows complex geometric feature that consists of a lower positive flower structure and an upper negative flower structure that is bounded by the Late Ordovician strata.On the seismic coherency slices,the lower strike-slip faults show NE linear extension and the upper strike-alip faults are NW trending and present right-order en-echelon arrangements.According to changes of the rising height of the interface and fault throw changes,the development history of the strike-slip faults may be divided into two stages including the Late Ordovician and the Middle Silurian-Middle Devonian.Combined with tectonic background analyses on the structures surrounding Tarim basin,the lower strike-slip faults and the upper en-echelon normal faults may be genetically linked.In the Late Ordovician,the Tazhong uplift experienced a strong compression from ancient Kunlun ocean subducting in NE direction,which resulted in the formation of NNE-trending strike-slip faults.During the Middle Silurian-Middle Devonian,intense folding orogeny of the Arkin tectonic domain caused the reactivation of the lower strike-slip faults and made the formation of the en-echelon normal faults was controlled by the early-stage basement weak zones.