THE TRANSFORMATION OF SOUTHERN ISRAEL FROM A SWELL TO A BASIN - STRATIGRAPHIC AND GEODYNAMIC IMPLICATIONS FOR INTRACONTINENTAL TECTONICS

The history of souther Israel during the similar to 100 Myr period bet ween the Cretaceous and the Eocene is an example of epeirogenic moveme nts which were controlled by magmatism and heating. Initially this reg ion was uplifted and became a local swell; then it subsided more than its surroundings and became a local basin. This study analyzes the sub sidence history of the region during its cooling for two purposes: fir st, to understand the relations between the tectonic patter of subside nce and the resulting stratal geometry, and second, to constrain the v olume of magmatism that intruded the lithosphere and perturbed the iso static equilibrium. Our results show that lateral changes in the inten sity of the tectonically-driven subsidence are not always expressed by simple corresponding changes in the thickness of sedimentary units. T he most prominent example of this was found in the Cenomanian section, which thickens northward in absolute contrast with the tectonic patte rn of subsidence during its deposition. The reason for this discrepanc y lies in lateral differences in the compactibility of the substrate u pon which these sediments were deposited. The two most important facto rs controlling the compactibility of the substrate are the thickness o f previously existing sediments and their history of uplift. Since sed iments that are reburied after an uplifting phase do not compact signi ficantly until they reach their previous maximal depth, we emphasize t he need to reveal the amount of exhumation from the amount of erosion hidden in unconformities. Our second aim was achieved only in part bec ause we cannot distinguish the subsidence caused by midlithospheric in trusions from secondary factors. One possible scenario that satisfies the observations is a combination of midlithospheric intrusions equiva lent to a 15-km-thick sill, plus thermal thinning of the lithosphere o f the same order. (C) 1998 Published by Elsevier Science B.V. All righ ts reserved.