Geology of the Fujairah 1: 50 000 map sheet 50-4, United Arab Emirates

Abstract

The Fujairah 1:50 000 geological map sheet covers a segment of the Hajar Mountains extending from the Gulf of Oman around the city of Fujairah in the east, to the desert plains of the Rub’ Al Khali in the west. The solid geology predominantly comprises rocks of the Oman-UAE ophiolite complex, with a small area in the centre-north underlain by medium- to high-grade metamorphic rocks (Bani Hamid Group). The ophiolitic rocks comprise an earlier magmatic suite of mantle harzburgite and dunite, overlain by a classic spreading-ridge crustal section of layered gabbro, through “high-level” gabbro (mainly isotropic to varitextured gabbro), to a Sheeted Dyke Complex and topmost pillow basalt. These were intruded by a later magmatic suite comprising some dunite, a predominantly ultramafic “Mixed Unit” (including peridotites and pyroxenites), voluminous wehrlite bodies, and a suite of younger gabbroic rocks and associated minor intrusions (various mafic dykes, tonalites and bodies of magmatic breccia). The metamorphic rocks occur as thin tectonic slices within a major north-west-trending fault zone. They fall within the P4 unit of the Bani Hamid Group of rocks and comprise quartz schists and quartzites, with minor amphibolites and calc-silicate rocks, metamorphosed under amphibolite facies conditions. The solid geology is partially covered by Miocene-Pliocene and Quaternary deposits. These are most extensive in the west, where the Hajar Mountains descend onto the desert plains and comprise palaeo-alluvial fan sands and gravels deposited on variably silicified serpentinite and mantle peridotites. These have been incised by Quaternary fluvial systems and are patchily overlain by Recent alluvial fan deposits. Elsewhere, the Quaternary deposits consist of alluvium and dissected river terraces, with scree and alluvial cones developed on the mountain slopes. Coastal zone deposits of the eastern seaboard include raised beaches and sabkhas, locally overlain by broad, low-angled alluvial fans issuing from the main wadis