SEQUENCE STRATIGRAPHY OF MIOCENE-PLIOCENE CARBONATE-SILICICLASTIC SHELF DEPOSITS IN THE EASTERN MEDITERRANEAN MARGIN (ISRAEL) - EFFECTS OF EUSTASY AND TECTONICS

Mio-Pliocene marine sediments comprise a discontinuous succession of c arbonates and mixed carbonate siliciclastics on the Neogene shelf, whi ch coincides with the Judean foothills area. On the slope (present Med iterranean coastal plain) the succession forms a wedge up to 1500 m th ick of mostly fine-grained siliciclastics. The facies and architecture of the succession were influenced both by sea-level fluctuation and b y the geodynamic change from thermally subsiding passive margins of th e Arabo-African plate to a complex pattern of vertical movements that were associated with the breakup of the plate along the Red Sea Rift a nd Dead Sea Transform and the convergence of the African-Arabian and E urasian plates. The Miocene eustatic succession is highly interrupted by vertical uplift tectonics, while the Pliocene eustatic succession i s well represented despite the limited subsidence rates. During most o f the Early and Middle Miocene the shelf was tectonically uplifted abo ve sea level, except for a short period of flooding in early-Middle Mi ocene times (N8, N9), when sea-level rise outstripped the uplift trend and a carbonate platform formed. The combination of tectonic uplift a nd sea-level fall prior to Late Miocene times (about 11 m.y. ago) resu lted in the incision of a deep Beer Sheva Canyon, about 280 m below th e shelf plane. Late Miocene sandy marlstones of the Bet Eshel cycle fi lled the Beer Sheva Canyon and spilled over it. They display a shallow ing-upward trend, resulting in progradational clinoform stacking of th e highstand systems tract, and channelled debris flows of the forced-r egression systems tract. The Messinian desiccation event left the shel f emerged while depositing evaporites on the slope and in the basin. T he degree of erosion during the Messinian was relatively minor because of arid conditions and limited runoff. The Pliocene shelf shows a ver y low subsidence rate and compared to the Miocene succession is less a ffected by vertical uplifts. The Pliocene deposits are divided into si x sequences. Their relative onlap curve largely corresponds to the seq uence stratigraphic scheme in Sicily and the Gulf of Mexico. The two l owermost sequences (I and II) are composed of two sandy units; the low er forms an incised valley fill of shoreface deposits in the Beer Shev a area, and offshore sand deposits in distal-shelf areas (Besor). Alth ough largely eroded, sequences I and II display maximum coastal onlap of all Pliocene cycles in the Beer Sheva Canyon area. Sequence III con sists of mixed carbonate-siliciclastic grainstones of shoreface/foresh ore deposits in the proximal area, and lower shoreface deposits in mor e distal areas. Sequences IV and V may be considered as a single 3rd-o rder cycle, where IV represents regressive lowstand (shale and sand) d eposits and V represents prograding highstand (sandy grainstone) depos its. Sequence VI consists of marginal-marine to coastal plain (marlsto nes and sands) deposits and is largely truncated by the Ahuzam Conglom erate, representing a major uplift phase of latest Pliocene to Early P leistocene age and marking the permanent emergence of the shelf.