(7) SEA LEVEL AND SEDIMENT SUPPLY FLUCTUATIONS DURING THE BOLLING-ALLEROD TO YOUNGER DRYAS TRANSITION REVEALED BY A 2D NUMERICAL MODELING OF THE CENTRAL ADRIATIC TRANSGRESSIVE RECORD

From Stratodynamics

Authors

Vittorio Maselli1,*, Eric W. Hutton2, Albert J. Kettner2, James P.M. Syvitski2 and Fabio Trincardi1

1 ISMAR-CNR, Istituto di Scienze Marine, Via Gobetti 101, 40129, Bologna, Italy


2 INSTAAR, Institute of Arctic and Alpine Research, University of Colorado, Boulder, Campus Box 450, Boulder, CO 80309-0450, USA

Corresponding Author: vittorio.maselli@bo.ismar.cnr.it

Abstract

Global sea level oscillations occurring during the Quaternary were mainly the consequence of changes in solar radiation pattern, tuned by the Earth’s orbital parameters (Hays et al., 1976), which regulate the waxing and waning on ice-sheets (Shackleton, 1987). On shorter time scales, i.e. the Late Pleistocene-Holocene, the sea level oscillation, still dominated by the Milankovian cyclicity, is also modulated by internal feed-back processes in the ice-ocean-atmosphere interaction (Bond et al., 1997; Clark et al., 2002), resulting in a step-like eustatic rise, with at least two periods of dramatically enhanced rates of ice melting and consequently sea level rise (Fairbanks, 1989). Although the overall timing and magnitude of the post-glacial sea level rise is well constrained (Bard et al., 1990; 1996), some uncertainties remain particularly around the Bolling-Allerod to Younger Dryas transition (Siddall et al., 2010; Carlson, 2010).

Here we try to quantify small-scale sea level oscillations that possibly occurred during this interval (14 -11 kyr BP) by simulating the deposition of the central Adriatic transgressive record (Maselli et al., 2011). This deposit consists of a tripartite sedimentary body with a central unit formed by a two steps prograding wedge with an internal unconformity (Cattaneo and Trincardi, 1999). The simulations are obtained by coupling two numerical models (Maselli et al., 2011), and are supported by sequence-stratigraphy analyses, core samples and 14C age estimates (Asioli et al., 2001). Model simulations with Hydrotrend v3.0, a hydrological water balance and transport model (Kettner and Syvitski, 2008), allow to simulate the total sediment discharge to the basin, highlighting high rates of sediment delivery within the interval between 13.8 and 11.5 cal. kyr BP as a consequence of increased rates of rainfall and partial melting of the Alpine glaciers. This result has been integrated in 2D Sedflux 1.0C, a basin-fill model able to simulate the margin stratigraphy (Syvitski and Hutton, 2001), that best reproduces the complex geometry of the tripartite transgressive record by introducing a minor sea level fall during the Younger Dryas. The results obtained also document the importance of shallow water sediment architecture in understanding past sea level fluctuations.

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