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Vol. 9 - 2010

Vol. 8 - 2009

Vol. 7 - 2008
SP 1 - 2008

Vol. 6 - 2007
Vol. 5 - 2006
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Vol. 2 - 2003
Vol. 1 - 2001-2002

Notes for Authors
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GeoActa Special Publication 1 2008


Acquisto online

GeoActa
an international Journal of Earth Sciences


Marco Roveri1, Stefano Lugli2, Vinicio Manzi1, B. Charlotte Schreiber3
1Dipartimento di Scienze della Terra, Università di Parma, Via G.P. Usberti, 157/A, 43100 Parma, Italy. E-mail: marco.roveri@unipr.it
2
Dipartimento di Scienze della Terra, Universitá di Modena e Reggio Emilia, Piazza S. Eufemia 19, 41100 Modena, Italy
3Department of Earth and Space Sciences, University of Washington, P.O. Box 351310, Seattle WA 98195, USA

The Messinian salinity crisis: a sequence-stratigraphic approach



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Abstract

A sequence stratigraphic framework of the Northern Apennines and Sicilian-Maghrebian foreland basins successions recording the Messinian salinity crisis (MSC) events is here presented.
Sedimentary evolution during the MSC was controlled by an interplay between tectonics and astronomically-induced climate changes. Precession-modulated climatic cycles produced elementary depositional sequences (EDS) whose key surfaces are the most prominent stratigraphic features at the outcrop scale.
EDS are stacked to form the systems tracts of two higher rank composite depositional sequences (CDS) separated by a sequence boundary corresponding to the subaerial Messinian erosional surface (MES). Such surface can be traced downbasin into a correlative conformity at the base of deep-water evaporite-bearing turbidite systems. Higher rank CDS are mainly controlled by tectonics and its side-effects on the hydrologic balance of the Mediterranean basin. Higher-rank systems tracts appear to be strongly influenced by climate changes at the obliquity and eccentricity scale as suggested by correlation of their bounding surfaces and vertical facies changes with isotope curves.
The resulting stratigraphic scenario has important implications for the MSC evolution. Lower Gypsum evaporites actually comprise both primary and resedimented facies which accumulated in different depocenters and at different times. Thus, two distinct stratigraphic units, Primary Lower Gypsum (PLG) and Resedimented Lower Gypsum (RLG), can be recognized. PLG deposits formed within shallow-water, restricted sub-basins during the highstand of the lower CDS between 5.96 and 5.61 Ma. RLG, associated in Sicily with Calcare di Base limestones and salt, accumulated in deeper water settings during the subsequent sea-level fall related to a high-amplitude evaporative drawdown and culminating at around 5.55 Ma with local salt basin fill and desiccation. The Sicilian Upper Gypsum was deposited in shallow water settings and is part of the lowstand and transgressive systems tracts marking the gradual refill of the Mediterranean basin with oligohaline to mesohaline waters. The sudden re-opening of the Atlantic gateways marks the MSC end at the base of the Pliocene (5.33 Ma) and the maximum flooding surface of the upper CDS.

Keywords: Sequence-stratigraphy, Messinian salinity crisis, Evaporites, Sicily, Mediterranean