Climate-controlled palynofacies and miospore stratigraphy of the Jauf Formation, Lower Devonian, northern Saudi Arabia

Abstract

The Jauf Formation miospore succession is synthesized in terms of palaeoenvironments and sequence stratigraphy. The data set for this study is obtained from four overlapping, continuously cored, and extensively sampled, boreholes that form a 940ft (287m) composite section. The Jauf Formation ranges in age from late Pragian to latest Emsian. The palynological assemblages, recognized herein, provide the basis for recognizing depositional environments present in the Lower Devonian of northern Saudi Arabia. Transgressive–regressive cycles are indicated not only by lithology, but also by marked changes in the marine to terrestrially dominated palynological assemblages, which are described in detail. Flooding events are recognized by the replacement of spore-dominated assemblages by organic-walled microphytoplankton and could be climate-controlled. The maximum flooding interval for the Jauf Formation is reinterpreted based on a correlative event consisting of diverse acritarchs and abundant chitinozoans. The sequence of palynological assemblages corresponds to fourth order cycles in the Hammamiyat Member. The new northern Gondwanan biozonation developed by Breuer and Steemans (2013) and used here allows a high-resolution regional biozonation for the Arabian Plate and larger-scale correlation of the Jauf Formation with other Gondwanan and Euramerican localities. One new spore genus (Zonohilates) and four new spore species (Insculptospora maxima, Camarozonotriletes alruwailii, Devonomonoletes crassus and Zonohilates vulneratus) are proposed.