Salt Tectonics and Their Relationships to Hydrocarbons in the Kuqa Foreland Fold-and-Thrust Belt, Northern Tarim Basin, China

Yixin Yu and Liangjie Tang
Basin and Reservoir Research Center, China University of Petroleum, Beijing, China

The aim of this paper is to investigate the styles, evolution and controlling mechanisms of salt tectonics and their relationships to hydrocarbons in the Kuqa foreland fold-and-thrust belt, northern Tarim basin, northwestern China. The field observations and interpretation of seismic profiles show that the salt tectonics, which can be divided into salt nappes, salt pillows, salt walls, salt welds, mini-basins and fish-tails of varying scales, are developed well in the Kuqa region. The intense structural distortion of salt tectonics occurred in the later Himalayan period from the Kuqa period to Quaternary. To comparatively analyze the major factors influencing the development of salt tectonics, the model of elastic-viscous plate showing the relationships between the salt and overburden has been established by virtue of thin film theory. The results indicate that the differential loading induced by the thicker sediments in the Baicheng sag dominated in the early stage of salt flowage. At present, however, the compressional stresses are the most important factor governing the development of salt tectonics. In addition, physical modelling demonstrates that the pre-Paleogene basement tectonics had important influence on the development of salt tectonics. The salt tectonics had exerted important influence on the hydrocarbon accumulations in the Kuqa foreland fold-and-thrust belt. The structural and subtle traps induced by the salt tectonics offered abundant favorable spaces for hydrocarbon accumulations, the faults acted as the favorable pathways for hydrocarbon migration and the thick halite layers served as good regional seals for hydrocarbon preservation. The forming models of hydrocarbon accumulations are different in the subsalt, salt and suprasalt in the Kuqa foreland fold-and-thrust belt.

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas