Isotope Stratigraphy of Oligocene Limestone in Al-Ain City, United Arab Emirates

The rocks of the Oligocene Asmari Formation represent the outer ridges surrounding Jabal Hafit anticline. The carbonate beds of this formation dip gently under the northern and western sides of Al-Ain city. The beds are dissected by several sets of joints and characterized by the abundance of the connected caves of different sizes, particularly in the thick chalky beds. In this study, petrographic and mineralogical studies by X-ray diffraction analysis and scanning electron microscope revealed that the examined carbonate rock samples are made up mainly of calcite and minor of authigenic dolomite and quartz minerals. The ⁸⁷Sr/⁸⁶Sr data obtained from the 8 fossils of Asmari Formation range between 0. 707989 and 0. 707835. The age of the analyzed rocks was estimated from the ⁸⁷Sr/⁸⁶Sr values that suggest a range from approximately 29. 6 to 33. 5 my (late Rupelian stage of the Oligocene).