Benthic foraminiferal assemblages from maximum flooding surface J30, Middle Jurassic Dhruma Formation, Central Saudi Arabia

Abstract

ABSTRACT: The benthic foraminiferal have been studied from mudstone-wackestones of the D5 Unit of the Dhruma Formation that represent the Middle Jurassic J30 maximum flooding surface of Sharland et al. (2001). The benthic assemblage consists of a mixture of smaller agglutinated species, Haplophragmoides, Kutsevella, Sculptobaculites, Trochammina), and calcareous species (Nautiloculina, nodosariids, ophthalmidiids, polymorphinids, and spirillinids) without any larger foraminifera. The assemblage is indicative of open-marine midshelf conditions, and contains a number of cosmopolitan taxa that are known from the Middle Jurassic in other areas of the Tethys. The recovery of open-marine and cosmopolitan smaller benthic foraminifera in the D5 Unit of the Dhruma Formation provides a new tool for identifying the J30 maximum flooding surface and correlating the interval with other regions of the Tethys.