GEOLOGICAL GIS MAPPING OF THE NORTHERNMOST PORTION OF THE SEMAIL OPHIOLITE COMPLEX, UNITED ARAB EMIRATES, EASTERN ARABIAN PLATE

The Semail Ophiolite on the eastern edge of the Arabian Peninsula is considered to be Earth’s most spectacular oceanic lithospheric complex. Its formation and obduction are associated with the closure of the Tethys Ocean during the Late Cretaceous. The complex forms a segmented mountain range approximately 800 km long and 75-130 km wide with a <5 km thick section of ultramafic and mafic rocks of Upper Mantle and ocean ridge affinity, with metamorphic sole rocks present. This study focused on the northernmost portion of the Semail Ophiolite in the United Arab Emirates bordered by the Gulf of Oman and is based on field observations, petrographic study, and satellite image analysis. The Upper Mantle is found to be represented by serpentinized peridotites with minor olivine gabbro. Oceanic crustal rocks include serpentinized peridotites and gabbros that show characteristic, low-temperature hydrothermal alteration and veining. Sole rocks near Jabel Dad are mica-quartz and carbonate-bearing schists documenting metamorphism and shear deformation of Mesozoic continental marginal sedimentites.

Reconnaissance field work provided sufficient ground control for a regional geological map construction using GIS methodology applied to LandSat ETM+ imagery. Spatial analysis was carried out by altering color frequencies and spectral bands to differentiate rock types. Rocks in the Wadi Hatta region of the NNE-trending massif are representative of the Upper Mantle section and can be distinguished from sole metamorphites. Adjacent Musandam Peninsula to the north shows oceanic crustal rocks of different spectral response and geomorphological characteristics. Regional tectonic surfaces are delineated and traced.

The combination of ground truthing along with an analysis of remotely sensed imagery allowed the construction of a geological map for the northernmost region of the Semail Ophiolite. This map, in combination with the geologic map information for the complex in Oman to the SE and earlier investigation results, enhances the understanding of the entire Semail Ophiolite complex. It demonstrates again the usefulness of GIS-based geologic mapping in remote and suitable terrains.