Structural Evolution of Lorestan salient in North Zagros Mountain Belt, Iran

Zagros foreland basin is the most important oil-gas foreland basin in the world. At least 60 oil and gas fields have been found. Therefore, research in this area will enrich the petroleum geological information of the foreland basin as an important basis for oil and gas exploration. First, we conduct 2D restoration of Lorestan salient in North Zagros Mountain Belt with 2DMove to test the rationality of the equilibrium profile and understand the structural evolution of the Lorestan salient. Base on the 2D restoration, faults evolved in the ways of in-sequence and out-of-sequence, many faults have breached the cover layer from basement then produced anticline, in the earlier stage of deformation. Anaran anticline and Kabir Kuh anticline caused by the thrusts that displacement along the thrust are 5769 m and 11496 m, respectively. The Vardalan, Dareh Baneh and Naft Anticline also produced by the basement thrust later, this result suggest that surface topography and anticline are highly associated with basement thrust. Second, using the Move2017-Surface to establish the 3D structural model to observe the lateral variation of the strata, some strata have lateral variation, the Mishan formation is absent in the NW but gradually appear to the SE and the Triassic carbonates thickness decreases from almost 1000 m in the southwest to 200 m in the northeast. This reduction in thickness may associated with late Triassic normal faulting and erosion. Third, we project the earthquake on the cross section to understanding the relation between earthquake distribution and tectonic patterns. Based on the analysis of seismicity and geological profiles, earthquake focal mechanisms are mostly reverse faulting with NW–SE strikes and the distribution is over whole horizontal Zagros belt but concentrated in depth of 5~16 km. In addition, larger magnitude earthquakes mainly distribute in southwest Lorestan, it implies that it is the main regime of active tectonics.