Stratigraphy and correlation of the Sarab Formation, Al Huqf Area, with the subsurface ara group play systems of Oman

Abstract

This study identifies and defines for the first time the Sarab Formation, a new formation in the uppermost part of the Ediacaran - Cambrian Huqf Supergroup of the Sultanate of Oman. The potential importance of this new formation is that it could be the long sought after outcrop- equivalent of the subsurface Ara Group, which is one of the most significant petroleum play systems in Oman. In most of the Huqf area, the Sarab Formation conformably overlies the Buah Formation. However, at some localities, on what were probably fault-bounded palaeo-topographic highs, the Sarab Formation rests unconformably either on the eroded Buah Formation or directly on the even older Shuram Formation. The Sarab Formation is overlain with marked angular unconformity by the siliciclastics of the Haima Supergroup. The formation is here formally described and subdivided into three principal members: the lower Ramayli Member, middle Shital Member and upper Aswad Member. A fourth member, the Salutiyyat Member, can be recognized where the Sarab Formation lies on eroded Nafun Group palaeo-topographic highs, and is probably the lateral equivalent, at least in part, of the upper Ramayli Member. The Ramayli and Shital Members contain evaporite units, including halite beds, and cyclical peritidal carbonates, indicating that the Huqf area was a trough or graben during this period. The middle and upper members contain significant microbial build-ups, including thrombolite framestone reefs, and rare crinkly laminites.