Tectonic vs. climate forcing in the Cenozoic sedimentary evolution of a foreland basin (Eastern Southalpine system, Italy) N. Mancin, A. Di Giulio and M. Cobianchi Dipartimento di Scienze della Terra, Universita' di Pavia, Pavia, Italy ABSTRACT This paper discusses the Cenozoic interaction of regional tectonics and climate changes.These processes were responsible for mass £ux from mountain belts to depositional basins in the eastern Alpine retro-foreland basin (Venetian^Friulian Basin). Our discussion is based on the depositional architecture and basin-scale depositional rate curves obtained from the decompacted thicknesses of stratigraphic units.We compare these data with the timing of tectonic deformation in the surrounding mountain ranges and the chronology of both long-term trends and short-term high- magnitude (‘aberrant’) episodes of climate change. Our results con¢rm that climate forcing (and especially aberrant episodes) impacted the depositional evolution of the basin, but that tectonics was the main factor driving sediment £ux in the basin up to the Late Miocene.The depositional rate remained below 0.1mmyear  1 on average from the Eocene to the Miocene, peaking at around 0.36 mm year  1 , during periods of maximum tectonic activity in the eastern Southern Alps.This dynamic strongly changed during the Pliocene^Pleistocene, when the basin-scale depositional rate increased to an average of 0.26 mm year  1 (Pliocene) and 0.73 mmyear  1 (Pleistocene).This result ¢ts nicely with the long-term global cooling trend recorded during this time interval. Nevertheless, we note that the timing of the observed increase may be connected with the presumed onset of major glaciations in the southern £ank of the Alps (0.7^0.9 Ma), the acceleration of the global cooling trend (since 3^4 Ma) and climate variability (in terms of magnitude and frequency). All these factors suggest that combined high-frequency and high-magnitude cooling^warming cycles are particularly powerful in promoting erosion in mid-latitude mountain belts and therefore in increasing the sediment £ux in foreland basins. INTRODUCTION The question of the relative roles played by tectonics and climate changes in guiding erosion, building mountain chains and producing sediments that accumulate in fore- land basins remains a matter of debate (Cederbom et al., 2004; Molnar, 2004; Allen, 2008; Vernon et al., 2008).Tec- tonics, climate and erosion interact as tectonics, via hori- zontal shortening, increases the thickness of the continental crust, thereby elevating the Earth’s surface and erosion removes rock masses, inducing an isostatic re- sponse (rebound) that elevates peaks above the surround- ing surface and produces new relief (Champagnac et al., 2007 and references therein).The two types of processes, however, operate over a very di¡erent timescales (Allen, 2008 and references therein): changes in tectonic condi- tions are very slow, on the order of several millions of years (Willett, 1999); whereas climate, in contrast, is ¢ckle, with periodicities on the order of 10 5 years (Zachos et al., 2001). As a result, it is di⁄cult to distinguish global climate ef- fects in the sedimentary records of tectonically active ba- sins. Consequently, it is challenging to determine how and by how much these signals may have been imprinted (Molnar, 2004). Researchers have also debated what are the most important climate-related factors that in£uence erosion^deposition dynamics in source-basin systems. In particular, we do not know whether long-term global tem- perature trends or short-term cooling^warming cycles are the main factors. Similarly, it remains unclear whether gla- ciation thresholds must be overcome in order to exert pri- mary control on sediment routing systems (e.g. Peizhen et al., 2001; Molnar, 2004). TheVenetian^ Friulian foreland basin (VFB) provides a good natural laboratory to study if and how climate signals are recorded in a tectonically controlled basin. In such a system, the entire Cenozoic history of the basin is well pre- served in the subsurface (mostly) and locally, also in surface exposure (Mancin et al., 2007) and the tectonic history of both the basin and surrounding belts is fairly well known (Fantoni et al., 2002 and references therein). This paper aims to explore the relationships between regional tectonics and climatic forcing in the depositional EAGE Correspondence: Nicoletta Mancin, Dipartimento di Scienze della Terra, Universita' di Pavia, via Ferrata 1, 27100 Pavia, Italy. E-mail: nmancin@dst.unipv.it Basin Research (2009) 21, 799–823, doi: 10.1111/j.1365-2117.2009.00402.x r 2009 The Authors Journal Compilation r Blackwell Publishing Ltd, European Association of Geoscientists & Engineers and International Association of Sedimentologists 799