Oman was on the northern margin of a wide late Tonian Mozambique Ocean

Abstract

The closure of the Mozambique Ocean defines the final assembly of the megacontinent Gondwana and is associated with a vast region of crustal growth in the Arabian-Nubian Shield. Despite this central paleogeographic position, there are few constraints on the position of terranes within and bounding the Mozambique Ocean. We report paleomagnetic data from ca. 726 Ma dikes exposed in southern Oman. Well-resolved magnetite magnetization is constrained to be primary by a conglomerate test on mafic clasts within overlying Cryogenian diamictite. The resulting paleomagnetic pole indicates that Oman was at a paleolatitude of 37 ± 2.5°N and was rotated ∼80° counterclockwise from its present-day orientation. This position is consistent with Oman forming a contiguous plate with the India and South China cratons on the northern margin of the Mozambique Ocean in a distinct tectonic domain from Arabian-Nubian arcs to the south. This position reveals an ∼5500-km-wide oceanic realm prior to subsequent closure that resulted in a major zone of Neoproterozoic crustal growth.