Gravity and Magnetic Investigation of Southeast of Al Ain, UAE – Implications for Evolution of Frontal Fold Belts of Oman

摘要

Gravity and magnetic investigation was carried out in southeast of Al Ain. The aim of the investigation was to determine the structural evolution of the area. The area is of tectonic significance because it can be used as a model for the Late Cretaceous and Tertiary structures which are developed in both the autochthonous and allochthonous rocks which outcrop along the flanks of the area. The study has revealed two major phases of tectonic events in the area. The first, a Late Cretaceous phase in the eastern part which is associated with both high magnetic (> 300 nT) and bouguer gravity (> -58 mGal) anomalies. These effects have resulted from the emplacement of the obduction-related thrust sheets of the Oman Mountains. The second, a Tertiary deformation phase that produces a series of southerly plunging asymmetrical anticlines and synclines trending in a NNW-SSE direction. Low gravity anomaly (<-74 mGal) in the centre of the study area was modelled as a sequence of post-Eocene carbonate sediments with a minimum thickness of 2km. The Tertiary folding and thrusting is formed as a result of regional compressive deformation due to the rejuvenation of the Late Cretaceous thrust faults during post- Middle Eocene.