Obduction and Collision Tectonics in Oman: Constraints from Structural and Thermal Analyses

Abstract

In Oman, Permian-Mesozoic sediments belonging to the Arabian passive margin were overthrust by Hawasina deep-water sediments and Semail Ophiolite in late Cretaceous. Passive margin sequences and Hawasina units are now exposed in the Hawasina, Jabal Akhdar and Saih Hatat domes and at the Oman Mountains thrust front. Structural analyses were performed in the Jabal Akhdar Dome and in the Musandam area (where the Oman Mountains are characterized by a syntaxis), and samples from sub-ophiolite sediments were collected in the Hawasina, Saih Hatat and Jabal Akhdar domes as well as at the Jabal Salakh and the Musandam thrust front. The thermal evolution of sub-ophiolite sediments was investigated by clay-size-fraction X-ray diffraction (analyses for Musandam, Hawasina and Saih Hatat samples are in progress) and 1D thermal modeling allowed us to infer that sub-ophiolite units of central Oman were thrust over by a 4.5 km-thick pile of Ophiolite and Hawasina rocks during the Coniacian age, and exhumed in late Campanian. The sub-ophiolite rocks at the Jabal Salakh front suffered a burial of 3.35 km of clastic and allochthonous units. The Musandam thrusts are characterized by a first phase of dip slip and a second phase of dextral strike slip kinematics.