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

Abstract

The Bani Hamid 1:25 000 geological map sheet covers an area in the central parts of the Hajar Mountains, which lies within the United Arab Emirates and the western part of the Omani enclave of Madhah. The Bani Hamid district spans the boundary between the Khor Fakkan and Aswad blocks of the Oman-UAE ophiolite. This boundary is defined by the north-west–south-east-trending Wadi Ham Fault, a series of sub-parallel anastomosing ductile shear zones and brittle faults, which also contains tectonically-bounded slivers of metamorphic rocks (Bani Hamid Group). Indeed, the boundaries of this special sheet were defined with the specific purpose of focussing on the high-grade rocks of the Bani Hamid Group, which fall on two map sheets in the 1:50 000 scale geological series (Khor Fakkan and Fujairah). The sheet contains most of the outcrops of the Bani Hamid Group, which forms a north-west–south-east-trending series of outcrops in the western part of the sheet and in a north-east–south-west-trending mountain range to the north and east. The Bani Hamid Group is subdivided into four informal units, based on packages with differing proportions of quartzite, amphibolite and calc-silicate rocks/marble. A small part of the Aswad block of the Oman-UAE ophiolite is exposed in the south-west corner of the sheet. This is composed mainly of units from the Moho Transition Zone (MTZ) and the lower crustal section, while the larger part of the map, to the north-east falls within the Khor Fakkan block and is made up chiefly of mantle harzburgite, passing up through the MTZ and lower crust along the eastern margin of the sheet. The Bani Hamid Group rocks are tectonically interleaved between two major nappes of mantle harzburgite within the Khor Fakkan block, the southernmost of which is extensively invaded by bodies of S-type granite. The solid geology is partially covered by sparse, but locally thick, Quaternary and Recent deposits, mostly within the major wadi systems such as Wadi Ham