oa The geology of Khuff outcrop equivalents in the United Arab Emirates

A revision of the stratigraphy of late Paleozoic and early Mesozoic carbonates in the Musandam Mountains near Ras Al Khaimah (United Arab Emirates) clarifies the presence of deposits that are age-equivalent to the Late Permian-Early Triassic Khuff Formation. Biostratigraphic markers including benthic foraminifera (e.g. Paradagmarita, Louisettita, Globivalvulina) and calcareous algae (e.g. Permocalculus, Gymnocodium) indicated a Late Permian (Lopingian) age ranging from Late Wuchiapingian to Late Changhsingian, corresponding to the K4 and K3 reservoir units in the subsurface. Sedimentological features, stacking patterns and microfacies of the outcropping carbonates show strong affinity to the KS4 to KS3 Khuff sequences, dominated by high-energy bioclastic pack- and grainstone. Outcrop gamma-ray data were used to identify the position of the Permian/Triassic boundary and to correlate the measured section with age-equivalent reservoir units. Some stratigraphic intervals in outcrop were affected by<br>pervasive dolomitisation and therefore the studied carbonates do not reflect the same rock properties as their subsurface counterparts. However, depositional facies showed clear resemblances to the reservoir facies, and the studied outcrop is palaeogeographically probably the closest location to the Khuff gas fields in the United Arab Emirates and Qatar.