Mechanics and Kinematic Evolution of Structural Styles Associated with Fold-Thrust Belt- Evidence of Inversion, UAE

Abstract

Oman Mountains deformation is being continued by massive thrust fault systems in Eastern Abu Dhabi basins with dissipating stresses laterally to the subsurface. Thrust faults with a strike-slip component that include a fault damage zone of strong rock shearing, and complicated zones of deformation. The initial episode was caused by the compressional movement of the Masirah, which faulted and folded again during the Semail tectonic events. Large faults are typically modelled on seismic as a single, large slip plane, but the outcrop analogues demonstrate the case is far more intricate, according to understanding of fault zone complexity and fault rock attributes. To understand the strength characteristics and seismic behaviour of faults in the subsurface, more in-depth information of the growth and structural style of thrust systems on outcrop analogues is essential considering the future exploration in eastern Abu Dhabi. Architecture, geometry, and tectonic uplift resulting from accumulated slip on the faults are all expressed at the surface that can express the geometrical prediction in subsurface. The paper describes the geological features and evidence of inversion structures, such as anticlines, reverse faults, and detachment surfaces, using seismic data, well logs, and surface outcrop analogues. It also explains the kinematic models, strain rates, and restoration methods used to understand the structural evolution and deformation history of the region. It highlights the positive and negative effects of inversion tectonics on hydrocarbon generation, migration, and trapping, and how they vary depending on the fault orientation, lithology, fluid pressure, and tectonic context. It suggests that the Abu Dhabi basin has experienced multiple phases of extension and compression, resulting from the interaction of the Arabian and Eurasian plates, and that the strike-slip faulting regime has played a significant role in shaping the basin geometry and hydrocarbon potential. This study has provided new insights into the geometry, timing, and driving mechanisms of thrusting deformation, as well as the regional tectonic implications of the fold-thrust belt. The fold-thrust belt can be further divided into three sub-belts, including the Northern Emirates zone, the eastern Abu Dhabi and the Abu Dhabi basin including onshore fields and further west. The former is characterized by imbricate stepped-thrust sheets composed of developed thrusts and related folds, and the detachment-fold sub-belt, which is composed of box, chevron, and closed overturned-isoclinal folds. The second eastern Abu Dhabi zone is characterized by thrust-fold sub-belt observed on seismic. The last western zone is mainly showing strike slip regime with few thrusts zones, which may due the transpressional regime between the fault segments.