The lower part of the Huqf Supergroup, comprising the Abu Mahara Group and the Hadash and Masirah Bay Formations of the Nafun Group, forms the oldest deposits exposed in Oman. This thesis is based on field study of this lower part of the Huqf Supergroup in the Jebel Akhdar and Huqf areas of Oman. The aim of the thesis is to provide a detailed sedimentological interpretation of this portion of the Oman stratigraphy, as well as analysing the implications of new chemostratigraphic and chronological data from Oman in a regional and global context. Volcanics and volcaniclastic deposits of the Halfayn Formation in the north of the Huqf area form the oldest deposits of the Huqf Supergroup. Previously, the Halfayn Formation has been correlated with volcanics that occur within the Abu Mahara Group of the Jebel Akhdar. However, U-Pb zircon dating of volcanic horizons suggests that the Halfayn Formation probably pre-dates the oldest deposits of the Jebel Akhdar by SOMyrs. An unconformity occurs at the top of the Halfayn Formation, and no further deposition is recorded in the Huqf area until the base of the Nafun Group. In the Jebel Akhdar, the Abu Mahara Group preserves a record of a particularly interesting period of Neoproterozoic time when widespread, possibly even global glaciations occurred. An ash bed from within a diamictite unit of the Ghubrah Formation has yielded a U-Pb zircon date of 711.8±1.6Ma. Comparing this to a previous date produced from the same bed of 723+16/-lOMa (Brasier et al., 2000), confirms that the glacial horizons of the Ghubrah Formation are Sturtian equivalents. The date of 711.8±1.6Ma actually comes from within a glacial unit, and consequently provides one of the best estimates yet produced on the age of the Sturtian glaciations. The Ghubrah Formation is overlain by the deposits of the Ghadir Manqil Formation, which form the upper part of the Abu Mahara Group in the Jebel Akhdar. Chronological and stratigraphic considerations suggest that the Ghadir Manqil Formation is actually a Marinoan equivalent, and that the boundary between the Ghubrah and Ghadir Manqil Formations represents an unconformity spanning c. lOOMyrs. At the base of the Ghadir Manqil Formation in the east of the Jebel Akhdar, the basaltic Saqlah Member occurs

The lower part of the Huqf Supergroup, comprising the Abu Mahara Group and the Hadash and Masirah Bay Formations of the Nafun Group, forms the oldest deposits exposed in Oman. This thesis is based on field study of this lower part of the Huqf Supergroup in the Jebel Akhdar and Huqf areas of Oman. Th...