WHAT CONTROLS THICKNESS OF SEDIMENTS AND LITHOSPHERIC DEFORMATION AT A PULL-APART BASIN?

Abstract

We present a simplified three-dimensional thermomechanical model of a pull-apart basin formed at an overstepping of an active continental transform fault. The modeling shows that for a given strike-slip displacement and friction on the faults, the major parameter that controls basin length, thickness of sediments, and deformation pattern beneath the basin is the thickness of the brittle layer. The unusually large length and sediment thickness of the Dead Sea basin, the classical pull-apart basin associated with the Dead Sea Transform, can be explained by 100 km of strike-slip motion and a thick (20-22 km, up to 27 km locally) brittle part of the cold lithosphere beneath the basin. The thinner sedimentary cover in the Gulf of Aqaba basin, located at the southernmost part of the Dead Sea Transform, close to the Red Sea Rift, is probably due to a thinner brittle part (<15 km) of the warmer lithosphere. modeling also suggests no more than 3 km moho uplift beneath narrow (10-15 pull-apart basins formed in cold lithosphere, such as dead sea basin. we infer that a basin may only form if several-kilometer-thick ductile detachment zone exists between brittle crust and upper mantle. shows this would not be case for surface heat flow there were indeed low 40 mw m2 as previously reported. We consider this result as an indication that the surface heat flow at the Dead Sea might have been underestimated. © 2006 Geological Society of America.