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The sea in the Jordan Rift (Northern Jordan) during Oligocene/Miocene transition with implications to the reconstruction of the geological history of the region

by Klaus Bandel, Hamburg & Rafie Shinaq, Irbid

 

BANDEL, K. & SHINAQ, R. (2003): The sea in the Jordan Rift (Northern Jordan) during Oligocene/Miocene transition with implications to the reconstruction of the geological history of the region. Freiberger Forschungshefte C 499: Paläontologie, Stratigraphie, Fazies (11): 97-115; Freiberg.

Abstract

During Late Cretaceous and Paleogene the shelf of the Arabian-African Continent in the area of north-western Jordan was differentiated into basins and swells, but received pelagic sediment, predominantly chalk. In the basin at the Wadi al Arab near Irbid deposition was not interrupted when the Cretaceous ended. With the end of the Eocene and begin of the Oligocene the sea withdrew and the area was uplifted and eroded. Rivers formed which in contrast to those of southern Jordan that continued across the land to end in the Mediterranean Sea ended in a newly forming and strongly subsiding rift valley. This depression was connected by a seaway to the north of Jordan with the Indo-Pacific Ocean in which sedimentation continued with perhaps an intermission during the late Chattian (transition from latest Oligocene into the Miocene). The shore of the sea within the northern Jordan Rift is documented from the modern slope and base in the Jordan Valley between Shuna near Yarmouk River and Wadi al Qarn near Abu Habil to the south. The sections near Waqqas documents flooding of the eroded Paleogene, near shore deposition, the presence of a shallow warm sea with rich marine fauna during the Aquitanian and its change into a salty environment with only cyanobacteria living during the Burdigalian. Into the near-shore environment rivers coming from the east deposited pebbles documenting erosion that uncovered continuously older beds of Paleogene age above to Late Cretaceous age below. An ancient river bed exposed near Awsara to the north of Ajlun Dome can be fitted with the near-shore marine deposits of Tayba Formation near Abu Habil exposed at almost Jordan River level. From a chalky bed found here a fauna of foraminifers is evaluated. Miocene deposition ended under the influence of very salty water and following sedimentation was that of Pliocene rivers and lakes. The Jordanian outcrops are related to subsurface data from the Rift only a few kilometers to the NW of Shuna. The Jordan Rift was active during the early Miocene, the graben became deepened and salt was deposited. The Dead Sea Transform fault has its position to the West of the exposures at Shuna, Waqqas and Abu Habil. Deformation was again strong during the end of the Pliocene, and subsidence continues.