Pliocene uplift of the Massif Central (France) constrained by the palaeoelevation quantified from the pollen record of sediments preserved along the Cantal Stratovolcano (Murat area)

Abstract

The French Massif Central is a key basement relief. This region experienced an intense period of alkaline volcanism, beginning with the Cantal Stratovolcano at 11 Ma and ending at 3 Ma. To quantify the palaeoelevation of the Cantal Stratovolcano and to replace it in the frame of the uplift history of the Massif Central, we first reconstructed the vegetation and climate based on a pollen analysis of the Murat diatomites, which were deposited in a maar lake. The vegetation was organized in three different belts: a Glyptostrobus swamp around the lake; a mixed forest; and, at higher altitudes, a conifer forest. The climate estimated using the climatic amplitude method indicates temperatures between 11.4 and 17°C. Using these estimates and comparison with contemporaneous sites, we infer a palaeoelevation for Murat between 710 and 930 m a.s.l. This site was therefore uplifted by 130 to perhaps 350 m during the Early Pliocene, leading to a reorganization of the drainage pattern and the capture of rivers flowing from the northern edge of the Massif Central towards the Atlantic Ocean. Our study confirms that the Cantal Stratovolcano was a high volcano (>2500 m) before its progressive dismantling during glacial episodes in the Pleistocene.