Sedimentary environment and diapirism of the Pleistocene–Holocene deposits of the Zirku salt plug, southern Arabian Gulf

Abstract

The Zirku salt plug is one of eleven emergent salt plugs in the southern Arabian Gulf. Its diapiric core consists of the Late Neoproterozoic–Early Cambrian ‘Hormuz Series’, which are unconformably overlain by ‘post-Hormuz’ calcarenite and breccia. The lithological and sedimentological characteristics of the calcarenite and breccia indicate that they were deposited in a beach and adjacent intertidal flats. It is suggested on stratigraphic grounds and the consideration of previous works that the ‘post-Hormuz’ deposits may be considered Pleistocene–Holocene in age. Diapirism affected the Pleistocene–Holocene deposits and produced mini-diapirs, intrusion and piercement structures, extruded gypsum flows, clastic dykes and diapiric uplift shown by elevated marine terraces and tidal notches. The elevated terraces and notches record sea-level high stands, uplift rates and sea-level fluctuations during the late Quaternary. The calculated rate of uplift of the Zirku salt plug during the period between 128 ka and 11 ka, is nearly constant at 1.05 mm/yr. Periods of transgressions and regressions were inferred from the late Quaternary sea-level curves. In the field, transgression is marked by onlap and the filling up of wadi channels, and regression by producing a new lower base level of wadis and the occurrence of gypcrete interbedded with calcarenite.