Morpho-structural analysis of Harrat Al Sham volcanic field Arabian plate (Syria, Jordan, and Saudi Arabia): methodology and application

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We present here a digital methodology aimed at identifying the morphometry of monogenic volcanic cones including edifice height, slope angle, and volume. We recognize more than 800 monogenic volcanic cones from the Harrat Ash Shaam volcanic province (HASV, northern Arabian Plate) to the north of the Arabian plate by using Landsat7 Enhanced Thematic Mapper plus and digital elevation models (Shuttle Radar Topography Mission, SRTM data). Our results show that the volcanic cones fall into six clusters, each one having a NW-SE orientation parallel to the Red Sea rifting. The density of the cones is most likely controlled by fissure distribution and a possible rotation in the HASV lithospheric block, rather than by the age of the volcanic activity. Interaction with crustal lithologies also plays a negligible role during magma migration. However, the morphology of the monogenic volcanic cones appears to be significantly modified by erosion processes, and both the height and slope of the various cones thus can be used to estimate their relative ages. From such morphological criteria, HASV monogenetic volcanoes in Jordan and Saudi Arabia are older than those in the Golan Heights and the Jabal Al Arab Mountain in Syria, thus, supporting the hypothesis of a northward migration of the recent explosive activity. Our new data, together with the available sediment thickness data, give rise to a new volcano-tectonic interpretation. We show that variations in the cumulative volume of monogenic volcanic cones in several zones of the study area can be related with the sediment thickness (basement depth), and therefore, we propose that the sediment thickness most likely affects the properties of magma before eruption. The reactivation of a deep previous fault perhaps also explains the higher volume of monogenic volcanic cones, focused along a well-defined alignment. This study, thus, gives insight into the relations between sediment thickness, the volcanism, and tectonics. Our results based on new digital treatment of remote sensing data are in overall good agreement with the volcano-tectonic evolution of HASV. This allows us to recommend this methodology as a potential tool to study volcanic cones of other inaccessible regions, either on Earth or other terrestrial planets.