Tectonic Evolution of Southern part of the Mesopotamian Foredeep Basin

Abstract

This study investigated the tectonic evolution of the southern part of the MesopotamianForedeep basin. Subsidence and sedimentation rates were calculated for six oil wellsdistributed on the tectonic subzones of the sedimentary basin through the use of restoredthickness rates according to Backstripping Method for Cretaceous and Tertiary sequences. Theconsequence of this study indicates the subsidence and sedimentation rates changing verticallyand laterally through geologic time. As shown, the sequences of Albain subcycle are widesubsidence and sedimentation rates especially for the Mauddud Formation at the Am-1wellwhich located in the eastern part of the sedimentary basin (Tigris subzone), as well as for thesequences of Cenomanian-Early Turonian subcycle especially for the Ahmadi and Mishrifformations were increase in subsidence and sedimentation rate toward (Am-2 and Mj-3) wells.Both wells located within the Tigris and the eastern part of Zubair subzone. This is inaccordance with the closure of the South Tethys Sea because of the influences of the Austrianand Subhersynian orogenies. Three unconformity surfaces determine clearly in the depositinalbasin of incompatibility during the Early Turonian, Danian and Oligocene epochs. Thoseunconformities affects all tectonic subzones except for the Am-1well where it was notinfluences by the unconformity during the Oligocene epoch. The subsidence and sedimentationprocess continued at high rates, reflecting the large thickness of the eastern part of the basin inthe Tigris subzone area. Sedimentation rates augment significantly at the well (AG-19), whichindicates the effect of faults on the Tigris subzone. This affects the degree of maturation andthe source of hydrocarbons in the sedimentary basin.