3.1.1. Neotectonics, climate and surface processes

Fig. 30. Numerical model for surface transport in the Romanian Carpathians. (a) Present-day observed topography and predicted drainage network using the historical mean runoff distribution. Numbers indicate water discharge (white, in m3/s) and sediment load (red, in kg/s) at selected locations of the Danube river and its tributaries. River width is plotted proportional to the predicted water discharge. (b) Predicted erosion/deposition (shade) and isostatic vertical velocity of the crust related to the surface mass transport (isolines labeled in mm/y; dashed lines correspond to uplift).U, S and O indicate present-day uplift, subsidence and stable topography, respectively, as inferred from geodetic leveling measurements (after Cloetingh et al., 2003b).

The Late Pleistocene and Holocene record of tectonic and climate changes is particularly intriguing in the light of the remarkable coincidence of societal evolution events and historical benchmarks that apparently were driven by environmental changes (e.g. Bada et al., 2005b). Most of the present climate reconstruction studies target isolated parts of the sediment source (mountains) to sink (basins) corridor that is subject to tectonically, as well as climatically induced changes. Correspondingly, the interrelation of these changes is poorly defined, and their mechanisms remain enigmatic (Fig. 29). Therefore, an integrated approach is required to unravel the response of the interacting parts of the complex source-to-sink system to tectonic and climatic changes. In this respect, Late Neogene source-sink systems, well documented for instance in the Carpathians by surface and subsurface data (e.g. Matenco and Bertotti, 2000; Matenco et al., 2003; Tărăpoancă et al., 2003; Dinu et al., 2005), will be analyzed in terms of their response to tectonics, controlling uplift of orogenic belts, the opening and closing of sea ways and the subsidence of sedimentary basins. These will be linked to climate changes, controlling erosion rates, sediment transport mechanisms and potentially the erosional break-down of tectonically-induced sills, controlling the erosional base-level in dammed-up sedimentary basins, as for instance at the Iron Gates straddling the South Carpathians-Balkans connection. The thus established past source-sink analogues, and their modelling, will aid in the understanding of recent changes (Fig. 30). Particularly, at the transition from the Pliocene to the Quaternary an enigmatic massive influx of sediments is observed, the tectonic and climatic signals of which are poorly understood (Necea et al., 2005). However, it is important to determine the neotectonic signal that underlies the Late Pleistocene and Holocene changes in the Alpine/Carpathian-Pannonian Basin system (e.g. Bertotti et al., 2003; Fodor et al., 2005). Precise dating and high-resolution correlations are prerequisites for sound geological constraints on thermo-mechanical modelling of basin geometries (e.g. Sanders et al., 1999). Particularly the recently developed state-of-the-art U-Th or nuclides methodology, combined with step-wise provenance studies, permit accurate dating of the most recent tectonic events that had a high human impact (e.g. Merten et al., 2005). Similarly, isotope geochronology provides an important tool for quantifying the timing and rate of erosion in source areas and sediment transport to actively subsiding basins, particularly during regional crisis events (e.g. Foeken et al., 2003; Ruszkiczay-Rudiger et al., 2005). Moreover, Pliocene-Quaternary climatic events can serve as time markers for unravelling signals that result from major plate tectonic processes that may be expressed by different types of deformation along the orogenic chain.