Microfacies and Environment of Upper Tuwaiq Mountain Limestone (Upper Jurassic) in Central Saudi Arabia PDF

Keywords

Saudi Arabia, limestone, environment

Abstract

The Tuwaiq Mountain Limestone is one of the five prominent rock units in the Upper Jurassic of central Saudi Arabia. It is 193 meters thick near the city of Riyadh. The Upper 90 meters of the formation is designated as the Upper Tuwaiq Mountain Limestone. It consists of light gray, hard, ledge forming biomicrite with abundant algae, corals and stromatoporoids. The most common fossil algae are the oncoidal forms of the blue-green alga genus Cayeuxia. The coral genera Amphiastraea and Microsolena are among the commonest remains of the frame-builders of possibly small reef-like structures. The Upper Tuwaiq Mountain Limestone was deposited in open marine environment of moderate depth. Surges of high turbulent water produced allochthonous facies particularly at the close of deposition.