Low-diversity, late maastrichtian and early Danian planktic foraminiferal assemblages of the Eastern Tethys

The eastern Tethys, from Israel to Egypt, experienced unusually adverse environmental conditions for planktic foraminifera during the last two million years of the Maastrichtian, as evident by very low species richness, blooms of opportunistic Guembelitria species in surface waters, dominance of low-oxygen-tolerant heterohelicids in subsurface waters, and near absence of deeper dwelling globotruncanids. Comparison of southern Israel (Mishor Rotem section) with central Egypt (Gebel Qreiya section) reveals that adverse conditions intensified towards the south with foraminiferal assemblages mimicking stress conditions of the early Danian, dominated (75-90%) by Guembelitria blooms. Faunal assemblages indicate an expanded oxygen minimum and dysoxic zone throughout the region, though at the greater depths represented by localities of southern Israel, bottom waters remained aerobic. Primary productivity was extremely low, as indicated by stable isotopes and low total organic content in sediments. These adverse environmental conditions are likely related to the regional paleobathymetry of the tectonically active Syrian Arc that spans Syria to Egypt. The paleorelief of intra-shelf and intra-slope basins of the Syrian Arc, with their differential rates of subsidence and sedimentation, active folding and faulting, likely controlled the intensity of circulation, upwelling, watermass stratification and the extent of the oxygen minimum zone. The late Maastrichtian rapid climate and sea level changes exacerbated these conditions.