U–Pb Age Dating for Carbonate Sequences: An Example from Late Neoproterozoic Kharus Formation, Al Jabal Al-Akhdar, Northern Oman: An Example from Late Neoproterozoic Kharus Formation, Al Jabal Al-Akhdar, Northern Oman

Abstract
Outcrops of the late Neoproterozoic carbonate Kharus Formation are time-equivalent to the subsurface Buah Formation in Oman Interior Basin. Kharus Formation belongs to the Nafun Group, overlying the Mu'aydin Formation with a transitional contact, and is overlain conformably by the late Neoproterozoic to early Cambrian Fara Formation, or unconformably (i.e., angular unconformity) by the Permian Saiq Formation. However, precise age dating of the Kharus Formation is not constrained yet due to the lack of fossils and absolute age results. Herein, we report results to constrain the Kharus Formation age using the direct in-situ U–Pb technique on carbonate samples. The samples were collected from the outcropped Kharus Formation at Wadi Bani Awf, Jabal Akhdar. The samples collected from the lower part of the Kharus Formation close to the contact with the Mu'aydin Formation yielded an age of 573 ± 28 Ma. In contrast, the samples from the uppermost part close to the Fara Formation provided a period of 564 ± 4.5 Ma. These ages are relatively comparable with the reported speculative age of the Kharus Formation (ca. 575–550 Ma) in the literature based on the dated overlying Fara Formation (ca. 544 ± 3.3 Ma) using zircon age dating. However, further refinement of the obtained results using the direct in-situ U–Pb age dating of carbonate successions is required. This can be achieved by analyzing samples not affected or less affected by diagenetic processes.