The Cretaceous/Paleogene boundary in Jordan

Abstract

The Cretaceous/Paleogene (K/Pg) boundary in Jordan is marked by a major depositional hiatus that differs in magnitude from place to place due to variable structural movements of the Syrian Arc Fold Belt that resulted in irregularity of Jordan/Levant depositional basin after the deposition of Maastrichtian succession. To elucidate the nature of this hiatus, fieldwork was carried out at a number of locations including lithofacies and stratigraphic analysis, and a multi-proxy study of microplanktonic biostratigraphy (calcareous nannofossilis and planktonic formaminifera). However, the duration of this hiatus extended over latest Maastrichtian and early Danian stages. This is based on the absence of the planktonic foraminifera; Pseudoguembelina hariaensis (CF3), Pseudoguembelina palpebra (CF2), Plummerita hantkeninoides (CF1), Guembelitria cretacea (P0), Parvularugoglobigerina eugubina (P&) zones and Parasubbotina pseudobulloides (P1a) subzones and the coeval calcareous nannofossils Nephrolithus frequens and Markalius inversus zones. We estimate that in the paleo-lows areas an unexpected 3.96Ma hiatus is present. Conversely, in swell areas, the duration of the hiatus represents the entire Danian–Selandian interval and revealed an unexpected 10.33Ma hiatus, especially in the central part of Jordan. Subsequently, a marked transgression took place over the whole of Jordan which resulted in the prevalence of deep water conditions (Zones P4 or equivalent NP7/8); this caused the deposition of a retrogradational parasequence set of middle shelf pelagic marl and chalk during a rapid relative rise of sea-level.A correlative hiatus and time gap have also been reported in different parts of the Arabian and African plates, indicating that Jordan was influenced by regional tectonics that combined with the latest Maastrichtian sea-level fall resulted in a long-term sub-marine hiatus and/or non-deposition of sediments. A combination of sea level changes and tectonic uplift are the likely cause for such a long gap in the sediment record in the region.