Keji YANG^1,2, Jiafu QI^1,2*, Baojun MA³, Tong SUN^1,2, Xichen ZHANG^1,2 & Shuai ZHANG^1,2
1State Key Laboratory of Petroleum Resource and Prospecting, China University of Petroleum, Beijing 102249, China;
²Department of Geology, China University of Petroleum, Beijing 102249, China;
³Hebei University of Geosciences, Shijiazhuang 050000, China;
*Corresponding author. E-mail address: qijiafu_cup@163.com

STRUCTURAL EVOLUTION AND CONTROLLING FACTS OF PIERCEMENT STRUCTURES IN THE KUQA DEPRESSION, TARIM BASIN, WESTERN CHINA

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A piercement structure, as a special type of a diapir structure, requires more complicated triggering conditions than a nonpiercement structure. This study investigates the geometric characteristics, evolution process, formation mechanism, and inducing conditions of piercement structures in the Kuqa depression, Tarim Basin, Western China by using new seismic and drilling data combined with variations in the regional and local stress environments. Results show that the development and distribution of piercement structures in the Kuqa depression are highly localized even in a continuously compressive environment. Piercement structures in the Kuqa depression mainly formed on top of pre-existing basement faults, particularly in the transition zone between uplift and sag, and in relatively narrow salt-bearing basins. The formation conditions for piercement structures in the Kuqa depression are extremely severe and include strong compression stress, reactivation of a pre-existing basement fault, and obstruction of the salt sedimentary boundary. Among these factors, compression stress is the most important dynamics for piercement structures. Pre-existing basement fault and salt sedimentary boundary control the development position. Lastly, a narrow salt sedimentary basin supplies a favorable formation environment.