Ostracods of the Permian-Triassic Khuff Formation, Saudi Arabia: palaeoecology and palaeobiogeography

Ostracods were recovered for the first time from outcrops of the Permian-Triassic Khuff Formation in central Saudi Arabia. The fauna is exceptional in that the Khuff lithofacies were not considered favourable for their development and preservation. This ostracod fauna positions the Triassic-Permian Boundary between the Lower and Upper Khartam members of the Khuff Formation. The palaeoecological analysis shows that the Saudi Arabian Permian ostracods are typical of a shallow, intertropical, warm-water setting. The evolution of the ostracods is directly linked with variations of sea level, and particularly the two Late Permian maximum flooding events: (1) at the base of the Midhnab Member (MFI PKm), and (2) within the Lower Khartam Member (MFI PKk). Some of the species discovered in the Saudi Arabian outcrops are known from other countries. The provincialism index (PI) was used to establish the palaeobiogeographic relationships between different Palaeo-Tethyan areas. A schematic model of oceanic currents is proposed to explain the spreading of species.