Depositional system and provenance of Cenozoic coarse sediments in Northern Fossa Magna

Abstract

Studies of stratigraphy and sedimentary system for Cenozoic sequence in the Northern Fossa Magna have progressed in these two decades. Especially a regional stratigraphical correlation using volcanic ash markers has remarkably progressed, and contributed markedly in the geological studies of the Northern Fossa Magna. The Upper Miocene to Pliocene sequence has been so far correlated on the basis of zoning of benthonic foraminifera in the petroleum geology. However, the stratigraphic correlation on the basis of this paleontological zoning is not consistent with the stratigraphical correlation using the volocanic ash markers. The contradiction between these stratigraphic correlations was examined in this study.
The geohistorical change of depositional system and tectonic evolution of the Northern Fossa Magna were discussed on the basis of sedimentary facies analysis and sedimentary petrography. Five geohistorical stages, namely pre-rift, rift, stable, conversion, and deformation stages, were consequently distinguished in the Cenozoic of the Northern Fossa Magna.