Tectonic and Geologic Settings of Halul and Al-Alyia Offshore Islands, Examples of Different Evolution Models, Within the Emergence of the Arabian Gulf Geosyncline: A Review

Abstract

The Arabian Gulf represents a significant water body and strategic pathway, which has pronounced regional and international benefits. This research investigated the evolution of the Arabian Gulf geosyncline. Furthermore, it explored the formation, geologic and tectonic settings of Halul and Al-Alyia offshore Islands, as examples of two different evolution models, within the emergence framework. The Arabian Gulf geosyncline has been emerged during the Cenozoic Era (Late Miocene-Pliocene Epoch), situated in the northeastern collisional marginal part of the Arabian Plate, as a foredeep geosyncline or basin, squeezed or crammed between the stable Arabian Plate and the mobile Euro-Asian Plate, along the subduction zone, within Zagros Mountain Fold Thrust Belt. Halul Island is situated to the northeast of the Greater Doha City and has great national economic value. It has a unique shape, elongated domal structure, oriented from South-West to North-East. The tectonic setting of Halul Island is classified as salt diapirism. The surface geology of this Island is dominated by carbonate rocks, mainly limestone and dolomitic limestone, and some igneous rock, such as basalt and Tholeiite. Al-Alyia Island is an integral part of the mainland. It is situated within the Greater Doha City's vicinity, in the eastern coastal zone. The Island is oriented from south-east to north-west. It is characterized by a gentle slope and low relief topography. The main rocks forming the island is the limestone and dolomitic limestone of the Simsima /Umm Bab Member of the Upper Dammam Formation of Tertiary age. This fact suggests that the island has a similar geologic setting to the mainland. This study revealed that the Halul Island evolution model is completely different from the evolution model of Al-Alyia Island, as Halul Island is a typical example model of salt dome Island, and remnants of the infracambrian salt basin, while Al-Alyia Island represents a different sedimentation model. This research has been carried out as part of the Environmental Science Center (ESC), Qatar University research agenda.