Late Cenozoic evolution of the Pannonian basin

Abstract

The Palaeozoic—Mesozoic nucleus of the Pannonian basin is the result of the collision of the European and Gondwanic microplates. The present basin was formed in the Late Cenozoic by the subsidence of this nucleus. The sinking was brought about by an active mantle diapir which was generated by the subduction associated with the formation of the surrounding mountains. The evidence and consequences of the mantle diapir are as follows. 1.(1) Strong Miocene andesitic-rhyolitic and Plio-Pleistocene basaltic volcanism.2.(2) Geothermal highs and the high value of reduced heat flow (Qo = 1.2−1.7 HFU).3.(3) Anomalous upper mantle with a lower density and elevated position of LVZ (low-velocity zone) and HCL (high-conductivity layer). The shallow depth of the HCL (40–60 km) shows that the geothermal highs are well developed in the upper mantle; this extra heat could not be the result of heat conduction only because of the young age (about 10 m.y.) of the basin, but convectionally transported heat has to be supposed as well.4.(4) Continental-type thin crust, thinned out by the subcrustal erosion of the mantle diapir. The primary cause of the basin formation is the isostatic sinking of the thinnedout crust.