Influence Of Tectonic Activities On The Evolution Of Salt Structures: Insights From Scaled Physical Modeling

This paper took Sudanese Red Sea rift basin and Amu Darya basin for examples, to discuss the deformation mechanism and the deformation characteristics of salt structures in the rift basin and the compression-relation basin. The major method of this paper was scaled physical modeling, which has been widely used to study the deformation mechanism and the deformation characteristics of salt structures in laboratory.Two different experiments investigated salt structural deformation and evolution in rift basin of Sudanese Red Sea with pure shear model and simple shear model respectively. During pure shear model extension, a horst-graben-horst structure was formed. A large number of high-angle faults, which spreaded upward and did not propagate across the rock salt strata to above-salt overburden, were produced in sub-salt strata and generated rift-related tilt-blocks. These rift-related tilt-blocks rotated during extension. Salt-relation structures such as salt-relation anticline and syncline were formed in above-salt overburden and salt structures such as salt swells and salt wall were produced in rock salt strata. Moreover, salt piercements were generated during the extension. During simple shear model extension, a scroll anticline-graben structure was formed. The thickness of rock salt would influence the structural deformation in basins. When it was thin, almost no salt structures were formed in rift basin, and faults in the sub-salt strata cut through the rock salt strata and got to the above-salt strata. But when thick, Faults mainly distributed in graben were in sub-salt strata and also spreaded upward but did not propagate to above-salt overburden. Salt structures such as salt swells and salt welds, even salt piercements were formed in rock salt strata in this model during the growth of scroll anticline. Compared to the seismic profiles of Sudanese Red Sea Area 15 and Area 13, the two experiments created similar structures, respectively. The two models created different structural styles showed that different basement styles and shear models had significant influence on salt deformation and evolution during extension in Sudanese Red Sea Basin.Also two different experiments examined salt structural deformation and evolution in Amu Darya basin with unilateral push. Experimental results showed that different depositional models affected structural deformation of rock salt and the sub-salt strata or above-salt overburden. Without syntectonic sedimentation in the compression process, thrusts and folds with the core of rock salt formed in the above-salt overburden which both near and far away from the push wall. It was also easy to form normal faults near the top of folds. With syntectonic sedimentation in the compression process, it was difficult to form thrusts and folds in the above-rock salt strata far away from the push wall and only salt gathering near the push wall. Compared to the actual seismic profile of Amu Darya basin, the experimental result showed that the salt structural deformation in Amu Darya basin was the production of Neogene new alpine tectonic activities and little influenced by syntectonic sedimentation.