Abstract
The Dead Sea Rift, a classic strike-slip basin, occurs along a transform that connects the Red Sea, where sea-floor spreading is occurring, to the Taurus Mountains, where plate convergence is occurring. The rift formed primarily from left-lateral displacement of about 105 km (65 mi) since the Miocene, producing uplift and normal faulting along its shoulders. Sedimentation within the transform occurs primarily in elongate, asymmetric pull-apart basins such as the Dead Sea, as transform segments pass each other along the zone of strike slip.
Pleistocene and Recent patterns of sedimentation were mapped on a scale of 1:50,000 along the west bank of the Dead Sea for a distance of 50 km (30 mi). Three sedimentologic units are recognized: an older sequence of debris flows and shallow-water fans; a medial unit of fan deltas interfingering with shallow-to-moderately deep-water lacustrine deposits; and an upper unit comprised of beach gravels, deltaic sands, and playa deposits. Their combined thickness is about 3,500 m (11,500 ft) along the western border fault, where they exhibit repetitive small-scale cyclical patterns of deposition within a general fan delta complex that prograded into the Dead Sea; there, geophysical studies show that the prograding subsea fans have been intruded by salt diapirs.
Such patterns of deposition clearly are related to recurrent movement along the border faults, producing rhomb-shaped basins, high-relief topography, and a unique rift climate. As the moist air rises over the shoulders of the rift, it cools adiabatically yielding as much as 800-1,000 mm (31-39 in.) of rain per year to high discharge ephemeral streams that transport huge quantities of coarse elastics into the basin. Conversely, as the air descends into the basin, it warms adiabatically, evaporating more than 2,000 mm (80 in.) of water per year, thus causing a concomitant drop in the Dead Sea level, precipitation of evaporites, change in the base level, and progradation of fans into deeper water.
