Sub- surface geometry of Howz Soltan basin and northwestern part of Zavieh basin, Central Iran Basin

We used 2D seismic profiles, well data and field observation to describe the sub- surface structural styles and geological history of two basins in the northern part of Central Iran Basin (the Howz Soltan and Zavieh basins) from Late Oligocene to Pliocene. Two basin- bounding faults with normal- slip component, the South Moreh Kuh Fault (SMF) and the Howz Soltan Fault (HSF), controlled the thickness of Qom Formation and lower part of Upper Red Formation (URF) in the Howz Soltan basin, particularly during the Early Miocene to early- Middle Miocene. In the Moreh Kuh area, there is also a facies change within the Early Miocene succession from the hanging wall to the footwall of a south- dipping inverted normal fault, the North Moreh Kuh Fault (NMF). The change from carbonated deposits of the Qom Formation (in the hanging wall) to clastic dominated URF (in the foot wall) indicates that the NMF had been a normal fault which was subsequently subjected to inversion. In the Zavieh basin, the Oligocene- Early Miocene succession thins onto the basin margins. The lower part of this interval shows an onlap from the north towards the basin margin. This could be an indication that the basin wall had been slightly inclined prior to the marine transgression. Since the Middle Miocene and/or Late Miocene, the initiation of a regional compressional phase resulted in folding and reverse faulting in the Zavieh and Howz Soltan basins. The deposition of upper URF and Pliocene units was simultaneous with this stage.