Integrated microfossil biostratigraphy, facies distribution, and depositional sequences of the upper Turonian to Campanian succession in northeast Egypt and Jordan

Abstract

Six upper Turonian to Campanian sections in Egypt (Sinai) and Jordan were studied for their microfossil biostratigraphy (calcareous nannofossils and planktonic foraminifera), facies distribution and sequence stratigraphic frameworks. Carbonate (mostly chalk) and chert lithofacies dominate the basinward northern sections passing laterally and vertically to mixed carbonate/siliciclastic lithofacies towards the shoreline in the southeast. Twenty-six lithofacies types have been identified and grouped into six lithofacies associations: littoral siliciclastic facies belt; peritidal carbonate; intertidal carbonate platform/ramp; high-energy ooidal shoals and shelly biostromes; shallow subtidal; and pelagic facies association. The following calcareous nannofossil biozones were recognized: Luianorhabdus malefomis (CC12) (late Turonian), Micula staurophora (CC14) (early Coniacian), Reinhardtites anthophorus (CC15) (late Coniacian), Lucianorhabdus cayeuxii (CC16) (early Santonian) and Broinsonia parca parca (CC18) (Campanian). Equivalent planktonic foraminifera zones recognized are: Dicarinella concavata (Coniacian), the lower most part of Dicarinella asymetrica (earliest Santonian) and Globotruncanita elevata (early Campanian). The integrated zonation presented here is considered to provide higher resolution than the use of either group alone. The absence of calcareous nannofossil biozones CC13 and CC17 in most of the studied sections, associated with regional vertical lithofacies changes, indicates that recognition of the Turonian/Coniacian and Santonian/Campanian stage boundary intervals in the region have been hampered by depositional hiatuses at major sequence boundaries resulting in incomplete sections. These disconformities are attributed to eustatic sea-level fluctuations and regional tectonics resulting from flexuring of the Syrian Arc fold belt. The Coniacian to Santonian succession can be divided into three third-order depositional sequences, which are bounded by four widely recognized sequence boundaries.