Shelf margin progradation of the early Ordovician Hiswah Formation in south Jordan

The outcrop understudy tests the retrogradational-progradational relationships during the deposition of the Early Ordovician Hiswah Formation in south Jordan. The investigated facies associations of the Hiswah Formation are... [ view full abstract ]

The outcrop understudy tests the retrogradational-progradational relationships during the deposition of the Early Ordovician Hiswah Formation in south Jordan. The investigated facies associations of the Hiswah Formation are comprised of fine-grained sandstones, siltstones and claystones (kaolinites). Fine-grained sandstones are characterized by ripple marks (oscillatory, current and interference), cross-bedding (trough and hummocky cross-stratification), deformed and contorted cross-beds, flaser bedding, ball and pillow structures, and water-escape structures due to differential loading. Biofacies includes graptolites, pelecypodes, and ichnofacies includes cruziana, ruzophycus, harlania and sabellarifex in addition to vertical and horizontal burrows. The lower boundary of the Hiswah Formation is marked by the gradual submergence of southern Jordan and the complete inundation by the Palaeotethys sea water. The dominance of fair weather processes is evidenced by the graptolite, skolithos and cruziana rich mudstones, interrupted by infrequent storm events depositing hummocky cross-stratified sandstones of the Hiswah Formation. The coarsening-upward succession of graptolitic claystones and storm-dominated sandstones indicate the gradual shallowing marine conditions of the palaeotethys, and the continuous Progradation stacked strata.