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Earth and Planetary Science Letters 444 (2016) 192â€“204 Contents lists available at ScienceDirect Earth and Planetary Science Letters www.elsevier.com/locate/epsl Quantiï¬cation of tsunami-induced ï¬‚ows on a Mediterranean carbonate ramp reveals catastrophic evolution Arnoud Slootman a,âˆ—, Matthieu J.B. Cartigny b, Andrea Moscariello a, Massimo Chiaradia a, Poppe L. de Boer c a Department of Earth Sciences, University of Geneva, Rue des MaraÃ®chers 13, Geneva 1205, Switzerland b National Oceanography Centre, University of Southampton Waterfront Campus, Southampton SO14 3ZH, UK c Faculty of Geosciences, Utrecht University, PO Box 80.115, 3508 TC Utrecht, The Netherlands article info abstract Article history: Cool-water carbonates are the dominant limestones in the Mediterranean Basin since the Early Pliocene. Received 26 August 2015 Their deposition typically resulted in ramp morphologies due to high rates of resedimentation. Several Received in revised form 31 March 2016 such fossil carbonate ramps are characterised by a bimodal facies stacking pattern, where background Accepted 31 March 2016 deposition of subaqueous dune and/or tempestite deposits is repeatedly interrupted by anomalously Editor: M. Frank thick sedimentary units, dominated by backset-stratiï¬cation formed by supercritical ï¬‚ows. A multitude of exceptional triggers (e.g. storms, ï¬‚oods, tsunamis) have been invoked to explain the origin of these Keywords: supercritical ï¬‚ows, which, in the absence of a quantitative analysis, remains speculative as yet. Here, carbonate ramp for the ï¬rst time, the catastrophic evolution of one such Mediterranean carbonate ramp, on Favignana Mediterranean Island (Italy), is quantiï¬ed by combining 87Sr/86Sr dating, outcrop-based palaeoï¬‚ow reconstructions and tsunami hydraulic calculations. We demonstrate that rare tsunami-induced ï¬‚ows, occurring on average once every storm 14 to 35 kyr, lasting a few hours only, deposited the anomalously thick backset-bedded units that form supercritical ï¬‚ow half of the sedimentary record. In between such events, cumulative two years of storm-induced ï¬‚ows catastrophic evolution deposited the remaining half of the succession by the stacking of subaqueous dunes. The two to four orders of magnitude difference in average recurrence period between the two ï¬‚ow types, and their associated sedimentation rates, emphasises the genetic differences between the two styles of deposition. In terms of sediment transport, the studied carbonate ramp was inactive for at least 99% of the time with gradual progradation during decennial to centennial storm activity. Carbonate ramp evolution attained a catastrophic signature by the contribution of rare tsunamis, producing short-lived, high-energy sediment gravity ï¬‚ows. Â© 2016 Elsevier B.V. All rights reserved. 1. Introduction Skeletal sand and gravel produced on the ramp top in the unpro- tected carbonate factory are transported downramp by incidental Cool-water carbonates in shallow, temperate seas are charac- currents, sweeping sediment below wave base. This results in the terised by the Heterozoan Association of James (1997), consisting occasional deposition of bioclastic material on the ramp slope, largely of the remains of red algae, bivalves, bryozoans, echinoids leading to carbonate ramp progradation through the formation of and larger foraminifera, in the general absence of non-skeletal large-scale clinoform units up to tens of metres high. grains. They lack the major bioconstructions and early cementation typical of their tropical counterparts (Ahr, 1973; Carannante and The sedimentary record of the Mediterranean Basin contains Simone, 1988). The skeletal debris-covered sea ï¬‚oors thus formed numerous examples of clinoform successions created in this way are prone to remobilisation and hence have a reduced capacity to (e.g. Hansen, 1999; Pomar and Tropeano, 2001; Pomar et al., 2002; accumulate above storm wave base (Pomar and Tropeano, 2001), Puga-BernabÃ©u et al., 2010; Massari and Dâ€™Alessandro, 2012), form- which may lead to the development of distally steepened ramp ing up to six-storey vertical stacks where carbonate ramps orig- proï¬les (Pomar et al., 2002; Pedley and Carannante, 2006) (Fig. 1B). inated in tectonically active areas, such as the Lower Pleistocene foreland and satellite basins of Sicily (e.g. Catalano et al., 1998; * Corresponding author. Massari and Dâ€™Alessandro, 2012). These clinoform successions, E-mail address: Arnoud.Slootman@unige.ch (A. Slootman). which prograded up to 1â€“2 km with a maximum height of sev- eral tens of metres, were suggested to correlate with the 41-kyr http://dx.doi.org/10.1016/j.epsl.2016.03.052 orbital obliquity-forced oscillation of global sea level related to the 0012-821X/Â© 2016 Elsevier B.V. All rights reserved.