The transformation of southern Israel from a swell to a basin: stratigraphic and geodynamic implications for intracontinental tectonics

Abstract

The history of southern Israel during the ∼100 Myr period between the Cretaceous and the Eocene is an example of epeirogenic movements which were controlled by magmatism and heating. Initially this region was uplifted and became a local swell; then it subsided more than its surroundings and became a local basin. This study analyzes the subsidence history of the region during its cooling for two purposes: first, to understand the relations between the tectonic pattern of subsidence and the resulting stratal geometry, and second, to constrain the volume of magmatism that intruded the lithosphere and perturbed the isostatic equilibrium. Our results show that lateral changes in the intensity of the tectonically-driven subsidence are not always expressed by simple corresponding changes in the thickness of sedimentary units. The most prominent example of this was found in the Cenomanian section, which thickens northward in absolute contrast with the tectonic pattern of subsidence during its deposition. The reason for this discrepancy lies in lateral differences in the compactibility of the substrate upon which these sediments were deposited. The two most important factors controlling the compactibility of the substrate are the thickness of previously existing sediments and their history of uplift. Since sediments that are reburied after an uplifting phase do not compact significantly until they reach their previous maximal depth, we emphasize the need to reveal the amount of exhumation from the amount of erosion hidden in unconformities. Our second aim was achieved only in part because we cannot distinguish the subsidence caused by midlithospheric intrusions from secondary factors. One possible scenario that satisfies the observations is a combination of midlithospheric intrusions equivalent to a 15-km-thick sill, plus thermal thinning of the lithosphere of the same order.