A Study of Gezzar Dolomite in Al-Khums Area

Abstract

This project is a study of the Gezzar dolomite in the study area which is located near Neggazah 18 km west of Al Khums town. The study area comprises two quarries, the first quarry is 1 km west of Neggazah, just south of the coastal highway, and the second one is 2 km southwest of Neggazah. From these two outcrops sixteen rock samples were taken. From these samples lithologic, petrographic and mineralogical studies were collected using petrographic microscope, XRD and SEM. Meanwhile the objective of this study is trying to know the origin of Gezzar dolomite and its difference with the Ayn Tobi member. Besides the economic importance of both Gezzar dolomite and Ayn Tobi member. Petrographic studies using the polarizing microscope and the scanning electron microscope revealed that the Gezzar dolomite is devoid of any gypsum and anhydrate. In this manner we would say that the Gezzar dolomite is Dorag dolomite rather than evaporative dolomite. Moreover, petrographic studies showed that this dolomite consist mainly of dolomite rhombs with a few calcites and aragonite. This dolomite has intercrystalline, vugy, and channel porosities. With regard to the differences between Gezzar dolomite and Ayn Tobi member field and lab evidences showed that the Gezzar dolomite consists mainly of thick to medium bedded gray and hard dolomite. While the Ayn Tobi member consists of dolomitic limestone, these dolomite beds are thick and almost barren of fossils when compared with Ayn Tobi member. Stratigraphic location showed that this dolomite was deposited earlier than Ayn Tobi member. This is simply because as we go up eastward towards Neggazah we find Ayn Tobi outcrops. Economically, the Gezzar Dolomite is an excellent source of pure Magnesium, temperature control in iron smelting plants, and the hardness of this dolomite  makes it suitable for masonry and it’s also used as crushed stones in building and highway constructions.