Intraplate volcanism in the Danube Basin of NW Hungary: 3D geophysical modelling of the Late Miocene Pásztori volcano

Abstract

Three-dimensional geophysical modelling of the early Late Miocene Pasztori volcano (ca. 11–10 Ma) and adjacent area in the Little Hungarian Plain Volcanic Field of the Danube Basin was carried out to get an insight into the most prominent intra-crustal structures here. We have used gridded gravity and magnetic data, interpreted seismic reflection sections and borehole data combined with re-evaluated geological constraints. Based on petrological analysis of core samples from available six exploration boreholes, the volcanic rocks consist of a series of alkaline trachytic and trachyandesitic volcanoclastic and effusive rocks. The measured magnetic susceptibilities of these samples are generally very low suggesting a deeper magnetic source. The age of the modelled Pasztori volcano, buried beneath a 2 km-thick Late Miocene-to-Quaternary sedimentary sequence, is 10.4 +/− 0.3 Ma belonging to the dominantly normal C5 chron. Our model includes crustal domains with different effective induced magnetizations and densities: uppermost 0.3–1.8 km thick layer of volcanoclastics underlain by a trachytic-trachyandesitic coherent and volcanoclastic rock units of a maximum 2 km thickness, with a top situated at minimal depth of 2.3 km, and a deeper magmatic pluton in a depth range of 5–15 km. The 3D model of the Danube Basin is consistent with observed high ΔZ magnetic anomalies above the volcano, while the observed Bouguer gravity anomalies correlate better with the crystalline basement depth. Our analysis contributes to deeper understanding of the crustal architecture and the evolution of the basin accompanied by alkaline intraplate volcanism.