Lithospheric structure of the Eastern Iranian plateau from integrated geophysical modeling: A transect from Makran to the Turan platform

Abstract

We present a 2D profile of density and temperature distribution in the lithosphere across Iran along a more than 1600km long profile extending from the Oman Gulf in the South to the Kopeh-Dagh and the Turan platform in the North. Gravity, geoid, topography and surface heat flow data were used for modeling, assuming local isostatic equilibrium. As much as possible, crustal structure has been constrained by seismic data. Crustal thickening is found under the Taftan-Bazman volcanic-arc (up to 47km), under the Binalud foreland (∼54km) and beneath the Kopeh-Dagh mountains (up to 50km) whereas thin crust has been obtained under the Oman Gulf (20km). Moho depth under the Lut block and the Turan platform is about 40km. The lithospheric thickness is ∼90km under the Oman Gulf and increases slightly until the Jazmourian depression. Then the lithospheric-asthenospheric boundary (LAB) bends significantly and sinks to ∼260km under the Taftan-Bazman volcanic-arc. The LAB depth is about 190km beneath the Lut block. A slight increase of LAB depth under the Binalud foreland towards the North may indicate a suture zone. Under the Turan platform, the LAB depth reaches ∼210km. We also modeled two possible positions of the deep suture zone in NE Iran (along the main Kopeh-Dagh fault or along the Atrak River) and concluded that, when the suture zone is along the Atrak River, we obtained the better fit between calculated and measured data.