Chronostratigraphy of the mixed Upper Cretaceous deposits at the northern margin of the Arabian Plate (Jordan)

This study provides an updated chronostratigraphy to the biozone level, integrating nannofossils, ammonites, benthic foraminifera, and Sr isotopes, for the mixed carbonate-siliciclastic-phosphatic-organic-rich Upper Cretaceous succession in south-central Jordan based on two well-exposed sections of 635 m and 712 m thick and located 100 km apart. Seven stratigraphic hiatuses have been identified, and significant changes in sedimentation rate are observed for this lithologically diverse stratigraphic succession. Well-dated surfaces are identified and provide unique and high-resolution calibration points for tectonic and paleoceanographically induced sedimentary system changes affecting the southeastern Neo-Tethys margin. The studied sections are located on the northern Arabian Plate continental shelf and contain a rich calcareous nannofossil assemblage that increases upwards in abundance and diversity. Ammonoids and benthic foraminifera helped to refine the Cenomanian and Turonian shallow water carbonate interval of the Ajlun Group. In the overlying Belqa Group, the integration of 87Sr/86Sr dating provided essential age constraints for the fossil barren shallow-water siliciclastic deposits of the Coniacian and Santonian, while it also provided calibration points for the nannofossil-rich Campanian and Maastrichtian strata. Age-depth and Bayesian statistics modeling constrain the duration and positions of the stratigraphic hiatuses, which show a consistent pattern between the 100 km spaced sections and have been correlated to the neighboring countries.