Messinian Events in the Mediterranean

Drooger, C. W.

doi:10.1029/sp005p0029

Cited by 14 publications

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“…Since there is no room for a large reservoir of brine at saturation in shallow playa lakes on the floor of the abyss, a sustained input of seawater to shallow brine pools is required to eventually precipitate the observed volume of halite (>1x10 6 km 3 ). Therefore, as Drooger [1973] probed, why was the gateway not enlarged as seawater poured into the Mediterranean chasm during this sustained period? Any enlargement of the gateway would be expected to trigger a run-away breach due to the positive feedback between enlargement of the entry cross-section and the escalating erosive power associated with the increased flux of water [Van Courvering et al, 1976;Ryan 2008].…”

Section: Geodynamic Implications Of Brine Concentration and Salt Precmentioning

confidence: 97%

“…If the closure occurred as drawdown got underway [Govers, 2009] we have to account for the same issue raised by Drooger [1973]. A cascade of saltwater into the Mediterranean from a perch at global sealevel would be expected to carve an ever-enlarging pathway, leading to an eventual runaway flood as happened when the passage opened in the strait of Gibraltar at the climax of the salinity crisis [Benson, 1973;McKenzie et al, 1990;Blanc, 2002;Garcia-Castellanos et al, 2009].…”

Section: Geodynamic Implications Of Brine Concentration and Salt Precmentioning

confidence: 98%

“…Why did the Atlantic water scour a permanent entrance only the last time? The more completely we suppose it desiccated many times during the Messinian, the more remarkable the fact that the obstructing barrier was not demolished well before the Pliocene [Drooger, 1973]. "…”

Section: Introductionmentioning

confidence: 95%

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Geodynamic responses to a two-step model of the Messinian salinity crisis

Ryan

2011

Bulletin De La Société Géologique De France

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There is a growing consensus that the sulfates and halite within the massive evaporite deposits on the shallow margin and deep floor of the Mediterranean sea formed in two steps. Both phases had geodynamic consequences. The current evidence indicates that during the first step when the first cycle "Lower Evaporites" were deposited primarily in marginal settings, the surface of the Mediterranean remained at or very close to the level of the external Atlantic. The geodynamic response resulted from the increasing weight of the brine layer as it concentrated from normal marine salinity to the threshold for sulfate precipitation and then to the threshold for halite precipitation. This weight alone significantly deepened the Mediterranean basins by isostatic loading. Flexure of the lithosphere caused a peripheral bulge to appear that may have been the agent to close off the further entry of Atlantic seawater.Step two began with the subsequent evaporative drawdown and the deposition of the second cycle "Upper Evaporites". As the basins dried out the loss of weight of the water led to regional isostatic uplift that permanently closed the prior inlets. Sediments removed from the margins by early subaqueous mass-wasting and later subaerial erosion and delivered to the basin floors further accentuated uplift of the margins and subsidence of the depocenters. The principal result has been to progressively tilt the Mediterranean substrate downwards from the margin towards the basin centers. This tilting was enhanced with the flooding of the desiccated sea at the climax of the salinity crisis. Consequently the salt layer rests today out of equilibrium on a surface that is more inclined after precipitation than before. The current mobility and flowage of the salt away from its margins and towards the basin centers is therefore not so much a response to the differential thickness and weight of overlying sediments, but to the combination of geodynamic processes that have produced the seaward tilting. Other giant salt deposits seem to have experienced a similar two-step evolution. Réponses géodynamiques au modèle en deux temps de la crise de salinité messinienneMots-clés. -Messinien, Méditerranée, Subsidence, Flexuration, HaliteRésumé. -Les sulfates et la halite des dépôts évaporitiques massifs méditerranéens de marge et de bassin relèvent de deux étapes différentes : cela fait l'objet d'un consensus qui s'élargit. Ces deux étapes eurent des conséquences géody-namiques. Il est actuellement démontré que, lorsque les évaporites de la première étape (appelées « Evaporites inférieu-res ») se déposèrent dans les bassins marginaux, le niveau marin méditerranéen resta très proche ou identique à celui de l'océan Atlantique. La réponse géodynamique vint du poids croissant du niveau à saumures où la concentration évolua de la salinité marine normale jusqu'aux seuils respectifs de précipitation des sulfates puis de la halite. Ce surpoids seul entraîna un certain approfondissement du bassin méditerranéen par réajustement isostatique. La flexur...

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Section: Geodynamic Implications Of Brine Concentration and Salt Precmentioning

confidence: 97%

Section: Geodynamic Implications Of Brine Concentration and Salt Precmentioning

confidence: 98%

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Geodynamic responses to a two-step model of the Messinian salinity crisis

Ryan

2011

Bulletin De La Société Géologique De France

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“…The Messinian succession (Fig. 2B) comprises pre-evaporite limestone and chalk, cobble conglomerates, sandstones and mudstones overlying the Mediterranean-scale unconformity that formed during the dramatic phase of sea-level fall that caused the well-known salinity crisis (Drooger & Broekman, 1973;Manzi et al, 2013;Gorini et al, 2019). During this period, many parts of the basin, as well as the continental shelf of the wider Mediterranean, were exposed subaerially and deeply incised by rivers (Madof et al, 2019).…”

Section: The Siderno Basin-fillmentioning

confidence: 99%

Anatomy of a mixed bioclastic–siliciclastic regressive tidal sand ridge: Facies‐based case study from the lower Pleistocene Siderno Strait, southern Italy

et al. 2021

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Sand ridges, a common feature of modern open shelves, reflect persistent currents and sediment availability under recent transgressive conditions. They represent the largest bedforms in the oceans and, as such, can yield information on long-term oceanographic processes. However, there is a limited number of tidal sand ridges documented from the rock record, examples of regressive tidal sand ridges are scarce and studies describing ridges in straits are even more rare. This study analyses a Gelasian succession within a structurally controlled, tide-dominated strait in the Siderno Basin, southern Italy. The strait connected two wider basins, and accumulated sediments reworked by amplified tidal (bi-directional) currents. A series of tidal sand ridges with superimposed dunes developed close to the south-eastern end of the strait, where bathymetry was deeper and flow expansion occurred. One of the best-exposed tidal sand ridges, 65 m thick, crops out along a ca 2 km long cliff. Large-scale, ESE-prograding, seaward-offlapping shingles contain sets of bioclastic-siliciclastic, coarse-grained, cross-stratified sandstones, erosionally overlying upper Pliocene shelf marls and fine-grained sandstones. Cross-strata show angular, tangential and sigmoidal foresets with compound architectures and a SSE migration, i.e. oblique to the main growth direction.Fossil content indicates open-marine conditions. The succession changes abruptly across an erosion surface to non-tidal, highly burrowed mixed siliciclastic-bioclastic fine-grained sandstones, less than 15 m thick. Documented features reflect stages of nucleation, active accretion and abandonment of an individual sand ridge, during a complete cycle of relative sea-level change. The ridge formed during a phase of normal regression, with accretion occurring during an initial highstand and the ensuing falling stage.

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Messinian Salinity Crisis

Lugli¹

Encyclopedia of Earth Sciences Series

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Messinian Events in the Mediterranean

Cited by 14 publications

References 0 publications

Geodynamic responses to a two-step model of the Messinian salinity crisis

Geodynamic responses to a two-step model of the Messinian salinity crisis

Anatomy of a mixed bioclastic–siliciclastic regressive tidal sand ridge: Facies‐based case study from the lower Pleistocene Siderno Strait, southern Italy

Messinian Salinity Crisis

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