Microfacial Study, Fossil Assemblages and Depositional Environment of Wadi As Sir Limestone Formation, Jordan

Abstract

This paper studies the microfacies, fossil contents, and the depositional environment of Wadi As Sir Limestone Formation exposed in the Al-tayyar area Zarqa Governorate, Northeastern Jordan. A total number of 35 samples were collected from a 30 m thick quarry section and used to prepare 35 thin sections. Some samples were washed over a 63 μm sieve, oven-dried at 50 ° C, sieved, and picked for benthic foraminifera analysis. Microscope analysis used to describe the microfacies and fossil contents. Four microfacies types and four lithological units are distinguished and described from the bottom to the top; the chalky unit (Unit-1) composed of bioclastic wackestone and biomicrite microfacies, and the dolomitic unit (Unit-2) immediately is existed above unit 1 composed dominantly of bioclastic mudstone and biomicrite microfacies. Marly limestone (Unit-3) is the following upwardly unit composed of bioclastic packestone and biosparite Microfacies, and the uppermost unit is limestone (Unit-4) consisted of bioclastic grainstone and biosparite microfacies. The fossil contents that were recognized in the studied thin sections and samples; bivalves, gastropods, pelecypods, cephalopods echinoderms, radiolarian, stromatoporoids, bone fragments, Saccaminopsis sp., Cibicidoides sp., Cibicides sp., Cyclammina sp., calcareous algae ( Koninckopora and gymnocodiaceans ), worm tubes, serpulids, and plentiful ostracods. The current study indicates that the Wadi As Sir Limestone Formation has deposited in a restricted circulation shallow shelf with low energy conditions most probably lagoonal environment.