Portrait of an Impact Strewn Field—Thermoclastic Ricochet Track: Eocene-Oligocene Transition (EOT), Jordan, Arabian Plate

Almost coevally with worldwide impact events, immediately at the beginning of the Eocene-Oligocene Transformation (EOT), (34.0 - 33.5 Ma), the Jordanian Platform and adjacent areas underwent an Impact Strewnfield/Ricochet-Scenery along a W/NW-striking ~400 km long strip, connected with triggered basalt magmatism (B1 - B3) and relating to the initial Red Sea Opening (34 Ma). The members of the Impact Ensemble expose along the “Fireline” a broad spectrum of characteristic impact structures (crater, ring structures, irregular structures) exhibiting thermo-clastic deformation ranging from low temperature to pyroxenite-sanidine hornfels facies of the Maastrichtian to Eocene target rocks (carbonate-, chert deposits), chert melt (~1400˚C: Jebel Waqf as Suwwan) and many mineral neoformations up to >1100˚C. Careful lithostratigraphic reviewing (including nannoplankton, and pelagic foraminifers) in the remote NE, near the Jordanian/Iraqi border area, and modern δ13C- and δ18C-isotope data of high resolution allow detailed age interpretation of impacting, triggered basalt magmatismus (B1 - B3) and lithofacies change from pelagic “Greenhouse”-carbonate rocks to oxygene-deficient bituminous baryte-bearing marls during step-wise microfauna extinction and high disturbance (“Cosmic Winter”-Environment: 34.0 - 33.9 Ma = 100 kyr). After the EOT, the lithofacies changed abruptly above a significant unconformity to glauconite-bearing mixed siliciclastics during the Early Oligocene Glacial Maximum (EOGM 33.5 - 33.0 Ma), followed by recovered lithofacies and microfauna under rising temperature. The subvolcanic precursors of the Red Sea-Opening (i.e. Sinai) penetrated the Arabian Shield by sills and dikes (44.42 - 41.34 Ma) and provided a restricted magma volume up to a surface near “highstand-level”, to be impact-triggered and to cause locally restricted outpourings (B1 - B3) or merely basaltic crater seams and jets without outflow. The major plateau basalt outpourings/harrats (B4 - B6) across the Arabian Shield took place during Oligocene-Miocene B. to the Pleistocene, directed by plate tectonic forces in connection with the Red Sea-rifting and the collision of the Arabian with the Eurasian Plates.