Patterns and trends of time–space evolution of Neogene volcanism in the Carpathian–Pannonian region: a review

Abstract

Based on a self-consistent K–Ar database completed with up-to-date geochronological information, this review paper addresses the general time–space evolution of Neogene magmatism in the Carpathian–Pannonian region, aiming at identifying significant patterns and trends. Grouped according to petrochemical criteria (felsic and intermediate calc-alkaline, alkaline) and major geotectonic units (Carpathian and intra-Carpathian, in turn divided into ALCAPA and TISZA-DACIA lithospheric blocks), the dated rocks reveal distinct evolution patterns. The intra-Carpathian area is characterized by (1) scattered, areal Eastward shifting magmatism, more developed on the ALCAPA block, involving felsic and intermediate calc-alkaline magmas in the early stage of evolution (21–7 My) and alkaline magmas in the later stages (11 to < 1 My), and (2) long-lasting magmatic activity spatially focused in an area ca. 200 km across located on the ALCAPA block, shifting in time from felsic to intermediate calc-alkaline and finally to alkaline compositions. We suggest that a mantle plume-type thermal anomaly was acting at the site of focused magmatism contributing to the development of higher volume areal-type magmatism in the same block, as compared with the later activated colder and more brittle TISZA-DACIA block. The Carpathian magmatism in turn displays two distinct time–space evolution patterns: (1) a long-lasting and slowly eastward migrating intermediate calc-alkaline magmatic front, active in the 15–9 My time interval along most of the Carpathian thrust-and-fold belt, generated in a subduction environment, and (2) a time-transient magmatism along the South-easternmost Carpathian segment, in the 11 to < 0.1 Ma time interval, whose purely subduction-related origin is questionable. Beyond these evolution patterns, two regional CPR-wide trends have also been identified: (1) the general Eastward shift of magmatic activity in time, irrespective of the chemical type, and (2) the convergence of magmatism in both time and space towards the South-eastern corner of the CPR (i.e. the Carpathian bend area in Romania), currently the geodynamically most active (and most hazardous) area of the whole CPR, including the Vrancea seismic structure. Eastward directed asthenospheric flow, possibly related to the inferred mantle plume responsible for the focused time-persistent volcanism on the ALCAPA block, might be considered as being at the origin of these evolutionary trends.