Messinian
The Messinian is in the geologic timescale the last age or uppermost stage of the Miocene. It spans the time between 7.246 ± 0.005 Ma and 5.333 ± 0.005 Ma (million years ago). It follows the Tortonian and is followed by the Zanclean, the first ...
evolution of the central
Mediterranean basin
In biogeography, the Mediterranean Basin (; also known as the Mediterranean Region or sometimes Mediterranea) is the region of lands around the Mediterranean Sea that have mostly a Mediterranean climate, with mild to cool, rainy winters and w ...
resulting from major drawdown of the
Mediterranean
The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the e ...
seawater
Seawater, or salt water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has appro ...
erosion
Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is distin ...
al events along the margins of the Mediterranean Basin during the Messinian timespan, before and during the evaporite deposition, were common.van Dijk, J.P., Barberis, A., Cantarella, G., and Massa, E. (1998); Central Mediterranean Messinian basin evolution. Tectono-eustasy or eustato-tectonics? Annales Tectonicae, 12, n. 1-2, 7-27. Those authors showed that also predating the deposition of the first cycle of evaporites, a major erosional phase can be observed along the basin margins, corresponding to a major " relative sea level drop", associated with tectonic activity (marking the end of the so-called "Mes-1" unconformity bound depositional sequence). Following this assumption that this major event corresponds to the major Messinian drawdown, Bache et al. (2009) concluded that the Mediterranean
bathymetry
Bathymetry (; ) is the study of underwater depth of ocean floors (''seabed topography''), lake floors, or river floors. In other words, bathymetry is the underwater equivalent to hypsometry or topography. The first recorded evidence of water de ...
significantly decreased before the precipitation of central basin evaporites. Van Dijk et al. (1998) had termed this end member scenario the "Hunchback Scenario". Regarding these works, a deep water formation for central Messinian evaporites seems unlikely. The assumption that central basin evaporites partly deposited under a high bathymetry and before the major phase of erosion should imply the observation of a major detritic event above evaporites in the basin. Such a depositional geometry has not been observed on data, as the detritic wedges are merely confined to the basin marginal areas.
Another major point of discussion regards the presence of erosional deep
canyon
A canyon (from ; archaic British English spelling: ''cañon''), or gorge, is a deep cleft between escarpments or cliffs resulting from weathering and the erosion, erosive activity of a river over geologic time scales. Rivers have a natural tenden ...
s along the
continental margin
A continental margin is the outer edge of continental crust abutting oceanic crust under coastal waters. It is one of the three major zones of the ocean floor, the other two being deep-ocean basins and mid-ocean ridges. The continental margin ...
s of the Basins. These should be expected to be present because of the assumption of a major
sea level
Mean sea level (MSL, often shortened to sea level) is an average surface level of one or more among Earth's coastal bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical datuma standardised g ...
drop. In fact, they have been described by several authors (summarized in e.g. Clauzon et al., 1996).Clauzon, G., Suc, J.P., Gautier, F., Berger, A., and Loutre, M.F. (1996); Alternate interpretation of the Messinian crisis: Controversy resolved? Geology, 24, 4, 363-366. Most of them are infilled by early
Pliocene
The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58 this phenomenon can be explained in two ways: A major eustatic sea level drop, or a tectonic uplift of the margins (as one associated with a minor sea level drop). It constitutes, therefore, not a real proof for the
desiccation
Desiccation () is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic (attracts and holds water) substance that induces or sustains such a state in its local vicinity in a moderately sealed container.
...
of an existing originally deep basin.
The third much-disputed element is the recognition of the so-called "MES", the Messinian Erosional Surface. This surface can well be traced in seismic sections along the Basin margins, showing angular and non-angular unconformities, somewhere within the evaporite deposits, or between evaporite and non-evaporite deposits. Nice examples are shown by Roveri et al. (2008).Roveri, M., Bertini, A., Cosentino, D., Di Stefano, A., Gennari, R., Gliozzi, E., Grossi, F., Iaccarino, S.M., Lugli, S., Manzi, V., and Taviani, M. (2008); A high-resolution stratigraphic framework for the latest Messinian events in the Mediterranean area. Stratigraphy, vol. 5, nos. 3-4, pp. 323-342, text-figures 1-9.
As already extensively discussed in van Dijk (1992),van Dijk, J.P. (1992, d); Late Neogene fore-arc basin evolution in the Calabrian Arc (Central Mediterranean). Tectonic sequence stratigraphy and dynamic geohistory. With special reference to the geology of Central Calabria. Geologica Ultrajectina, 92, 288 pp. the erosional surfaces within the Messinian clastic and evaporitic and mixed series are often confused. Only very high resolution and complete series such as those in the Crotone Basin in
can solve this matter, and the authors have shown that the erosional surfaces and there probable relationships with relative sea level fluctuations and tectonic activity can be mapped well (see review in van Dijk et al., 1998).