Abstract

A revised formal lithostratigraphy for the Mesozoic to Cenozoic succession of the onshore portion of the Rovuma Basin in northern Mozambique replaces a previous mixture of informal lithostratigraphical and biostratigraphical names. The following nine formations are formally described: Rio Mecole Formation (Jurassic? age), N’Gapa Formation (Jurassic? age), Pemba Formation (late Jurassic and early Cretaceous age), Macomia Formation (Aptian-Albian age), Mifume Formation (Albian (offshore)/Campanian (onshore)-Maastrichtian age), Alto Jingone Formation (Paleocene-Eocene age), Quissanga Formation (middle Eocene-Oligocene age), Chinda Formation (Neogene age) and Mikindani Formation (Neogene age). The basin’s geology records the temporal development of the coastline of northern Mozambique and southern Tanzania over the last c. 200 million years. Intracratonic rift-basins formed during the early Jurassic Period developed into a south-facing gulf prior to complete separation of eastern Africa from the rest of eastern Gondwana in early Cretaceous times. Concomitant with the lateral crustal movements, vertical isostatic and locally fault-controlled, uplift was a major influence on sedimentation in eastern Africa. This led to erosion with high-energy, fluvial sedimentation into the rift-basins and the establishment of a marine basin throughout the Cretaceous Period. Reduced sedimentation rates during the Paleocene and Eocene were followed by regenerated river-transported sedimentation due to doming and erosion of eastern Africa associated with the development of the East African Rift System since the Oligocene. The major onshore faults that control the shape of the Rovuma Basin and which have been intermittently active since the Jurassic cut across the east-northeast to west-southwest structural grain of the underlying Precambrian crystalline rocks of the East African Orogen. However, some of the east-northeast to west-southwest transfer faults identified in the offshore part of the Rovuma Basin may represent, in part, reactivated Pan African ductile shears

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