Early paleogene geohistory of Egypt: The Dababiya Quarry corehole

摘要

Following a decade of studies in search of appropriate criteria for selecting/defining and characterizing/correlating an optinum location/level for a GSSP, the Working Group on the Paleocene/Eocene boundary selected the 1.65 m level at the base of Section DBH in the Dababiya Quarry, on the east bank of the Nile River, about 35 km south of Luxor, Egypt (text-figs. 1-3). This level is correlative with the onset of a Carbon Isotope Excursion(CIE) that was denoted as the primary criterion for recognition and correlation of the Eocene GSSP. This (lithologic) definition was formalized (Aubry et al. 2007) following ratification by the IUGS at the 33rd IGC (Florence, August 2004). The basal Bed 1, the oldest bed of the Eocene Epoch, is a dark gray clay, and one of ive characteristic beds (named the "Dababiya Quarry Beds", Ouda and Aubry, eds., 2003, text-figs. 4a and b, this paper) that outcrop through extensive areas of the Middle East. These five beds (~3.5 m-thick in the Dababiya GSSP section) that occur in an otherwise monotonous lithology of shales (~120 m in the quarry) are indicative of a major diruption that affected the Earth system at the time of their deposition. Elsewhere, this disruption has left its mark in the sedimentary record, in most instances with abrupt changes in lithology.