Vase-shaped microfossils and possible trochamminid foraminifera from the Ediacaran Dhaiqa Formation of Saudi Arabia

Abstract

We report the first discovery of vase-shaped microfossils (VSMs) and possible multichambered foraminifera from the Ediacaran rocks of Saudi Arabia. The Ediacaran successions of Saudi Arabia are well exposed in the northwestern and central part of the Arabian plate but are relatively understudied due to the lack of economic potential. The exposures can be found in different small sedimentary basins distributed along the flanks of Najd Fault system of the western Arabian Plate. The Dhaiqa sub-basin located near the historic city of Al-Ula contains some of the best exposures of Ediacaran Mattar and Dhaiqa Formations with collective exposure almost 400 m thick. These formations (especially the Dhaiqa Formation) were investigated to describe sedimentary facies, depositional environment, and possible microfossils. This study focuses on the identification of vase-shaped microfossils and possible trochamminid foraminifera of Ediacaran age that are herein recognized for the first time in Saudi Arabia. Outcrop samples were thin-sectioned and analyzed to reveal nine sedimentary facies belonging to four facies associations. The observed microfossils were found in a total of four samples from the cherty/siliceous carbonate and sandy microbialite facies. The microfossils are observed to be associated with diagenetic chert, which is abundant in these facies. The two facies contain a sparse microfossil assemblage with vase-shaped microfossils, which are single-chambered microfossils of uncertain taxonomic affinity, and possible multichambered agglutinated foraminifera that resemble trochamminids.