Stratigraphy, 40Ar–39Ar dating and erosional history of Svínafell, SE-Iceland

Abstract

The interplay of volcanism and erosion in the Svínafell massif, on the western slope of the Öræfajökull volcanic center, SE-Iceland, is traced with geological mapping, magnetostratigraphy and $^{40}$Ar–$^{39}$Ar age determinations. The volcanic strata are mainly of Quaternary age, i.e., geomagnetic chrons of lower Matuyama to upper Brunhes. The 1832 m thick sequence in Svínafell is composed of 37 discrete lithologic formations, assigned to seven volcano-stratigraphic groups beginning with the onset of volcanism in the Öræfajökull stratovolcano during lower Brunhes magnetic chron (C1n < 781 ka). A regional basin formed shortly before the initiation of volcanism, generating a depocenter for the plant-fossil bearing Svínafell sediments between 0.70 and 1.78 Ma. The Svínafell volcanic strata accumulated during a minimum of eight glacial and inter-glacial stages. We document the Svínafell erosion history and landscape evolution, including 12 erosion surfaces. Erosion has led to extended stratigraphic hiatuses and removal of thick volcanic sequences.