Multi-Decollement Structure Modeling of Kuqa Fold-Thrust Belt in Tarim Basin

The structure model of Kuqa fold-thrust belt in Tarim basin is very complex and special. The Paleogene gypsum-salt strata and Jurassic-Triassic coal measure strata are two detachment layers developed in Kuqa area, and both of them have a large thickness. The shallow structure is salt-related structure which developed above the Paleogene gypsum-salt stratum, there is a large difference with typical salt-related structure because this structure was seriously affected by overthrusting but not by gravity action. The structure style mainly contains salt-loss syncline, salt diaper, piggy-back basin and salt fold. The structures between the two detachment layers developed double detachment structure with a special structure style. The double detachment structure has obvious differences with typical fault-related fold, analyzing from kinetics, we can see that the deformation of fault-related fold was driven by bearing stress which was produced by the contact of different fault blocks, but the deformation of double detachment structure was driven by plastic flowing of the detachment layers; analyzing from geometry, we can see that double detachment structure developed the “suspended structure”, this is the obviously different with fault-related fold. Analyzing from the structure characteristics, the Kuqa fold-thrust belt have been developed a whole thrust system from the mountain front to foreland. In order to make a deeply research of the structure style in Kuqa fold-thrust belt, we use the 3D model building technique, structure restoring technique and 4D physical modeling technique, and these techniques has been made a very important role in the research.