Thermal history of Tertiary basins in Slovenia (Alpine-Dinaride-Pannonian junction)

The transition zone between the Alps, the Dinarides, and the Pannonian Basi n was affected by syn-collisional magmatism in Oligocene time and post-coll isional lateral escape followed by extreme extension in early and middle Mi ocene times. Numeric heat flow models for sixteen sites and 650 vitrinite r eflectance data from Paleogene and Neogene sediments were used to evaluate temporal and lateral heat flow variations related to these events. Oligocene. Oligocene (Smrekovec) volcanism is the main heat source for Pale ogene sediments south of the Periadriatic Lineament. Vitrinite reflectance patterns suggest dextral displacement along the Donat Fault of the order of 50 km. Coalification of Paleogene coal-bearing sequences south of the Poho rje is a result of the emplacement of the Oligocene Pohorje tonalite. Early/middle Miocene. Extremely elevated early/middle Miocene heat flow (> 200 mW/m(2)) occurred in the Styrian Basin, the Pohorje area, the Maribor-R adgona area, and along the Boc Anticline. It is partly a consequence of mag matic activity. However, no igneous rocks are known from the Maribor-Radgon a area. A large shallow early Miocene pluton could explain the observed Mio cene heat flow. Rapid uplift of hot basement rocks in the Pohorje/Kozjak re gion may have increased surface heat flow. Neither volcanic rocks nor metam orphic core complexes are known from the Boc area. The Ormoz-Selnica Anticl ine was probably influenced by a middle Miocene heating event (similar to 1 50 mW/m(2)). Coeval volcanism south of the anticline represents a potential heat source. Post-middle Miocene. The WSW-ENE-trending Ljutomer and Radgona Depressions are characterized by moderate Neogene heat flow (60-75 mW/m(2)), whereas la te Miocene to present-day heat flow in the Ormoz-Selnica Anticline is 80-90 mW/m(2). A recent heat flow anomaly occurs in the Somat-Benedikt area. (C) 2001 Elsevier Science B.V. All rights reserved.