Extensive glacigenic suites of sediments were deposited throughout Arabia during the late Paleozoic glaciation of Gondwana. In the Sultanate of Oman, the glacigenic Moscovian to Sakmarian Al Khlata Formation directly overlies the widespread “Hercynian” unconformity and is succeeded by the postglacial Gharif Formation, indicating that intermittent glacial conditions in the Arabian Peninsula lasted at least 15 m.y., and possibly up to 30 m.y. Sedimentological and stratigraphic relationships are complex, and rapidly evolving lithofacies associations are often difficult to correlate. Palynological dating has proven extremely beneficial in facilitating correlation in the subsurface and has permitted the development of a regional stratigraphic framework and tentative correlation with coeval glacigenic sequences of Saudi Arabia. A lower association of sand-dominated proglacial braided fluvial and deltaic facies that pass laterally into glaciolacustrine facies is common to both Oman and Saudi Arabia. It is overlain by an upper association that was deposited during widespread glaciolacustrine conditions related to the terminal decline of Gondwanan ice in Arabia. The postglacial transition is marked by the onset of continental to marginal-marine red-bed and carbonate deposition.

Abstract The fluvio-dcltaic Pikeville. Hyden, and Four Comers Formations of the Breathitt Group in eastern Kentucky represent three superimposed 3rd-order composite sequences comprising stacked aggradational. progradational. and retrogradational 4th-ordcr sequences. These define lowstand. transgressive. and highstand sequence sets. Incised-valley fill (IVF) deposits overlie the sequence boundaries and are predominantly characterised by fluvial sandstone fill with only limited fine-grained partings. Third-order IVF's are thicker and more laterally extensive than 4th-order variants and also contain parasequences related to 4th-order cyclicity. IVFs were deposited during aggradation when the accommodation rate was in equilibrium with sediment supply. Each sequence set has a distinctive stacking pattern of 4th-order IVFs in terms of the degree of incision and the amount of transgressive and highstand deposits preserved between. 4th-order sequence boundaries. The lowstand sequence set contains the most amalgamated IVFs while the transgressive sequence set contains the least amalgamated. The position of 4th-order sequences on a 3rd-order relative sea-level curve is critical in controlling both the fill and stacking of IVFs. The stacking of 4th-order sequences into sequence sets has important implications for hydrocarbon exploration and production. The number of individual sandstone beds within 4th-ordcr sequences offers multiple stacked reservoir targets, especially within the lowstand sequence set. which contains the greatest proportion of sandstone.