Neoproterozoic-early palaeozoic tectonic evolution of Oman revisited: implications for the consolidation of Gondwana

Implications of a new tectonic evolution model that puts Oman at the eastern margin of the Mozambique Ocean during the Neoproterozoic are wide and regionally significant. This model helps understanding the Neoproterozoic tectonics and paleogeography of Gondwana, the closure of the Mozambique Ocean, the paleogeography of the world-renowned Cryogenian and Ediacaran successions of Oman, and the petroleum systems of Oman and the rest of Arabia. The proposed evolution model implies that the basement of Oman formed at the margin of Neoproterozoic India, and that the Cryogenian-Ediacaran sedimentary succession of Oman, and its early tectonic evolution, whose structural trends influenced tectonics through its geological history, were separate from those of the Arabian-Nubian Shield to the west*, as they were on opposite sides of the Mozambique Ocean up to the early Cambrian. It also implies that the final Gondwanan suture lies somewhere along, or just west of, the Western Deformation Front, an early Cambrian orogenic belt now found in the subsurface of Oman and in outcrops of north and south Oman. Its development is related to Malagasy-Angudan Orogeny, and it separates two realms: the juvenile Ediacaran basement and active margin sedimentary successions of the Arabian-Nubian Shield, and the Tonian igneous and metamorphic basement, Cryogenian rift deposits and Ediacaran passive margin deposits of Oman/Neoproterozoic India. The Precambrian hydrocarbon systems of Oman do therefore not extend to western Arabia, but to India and Pakistan instead. Sediment provenance studies using zircon geochronology and facies maps of the Neoproterozoic successions help to understand the tectonic setting during deposition and the distribution of reservoir rocks in shallow water settings in northeast Oman, and source rocks in deep basinal settings in south and west Oman.