Changes in Mediterranean circulation and water characteristics due to restriction of the Atlantic connection: a high-resolution ocean model

Topper, R. P. M.; Meijer, Paul

doi:10.5194/cp-11-233-2015

Cited by 14 publications

(21 citation statements)

References 80 publications

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“…1,5 & 6). In order to investigate the gateway dimension problem, Topper and Meijer (2015) used a regional ocean model to examine how a restricted Mediterranean-Atlantic connection would influence both Mediterranean thermohaline circulation and water properties. This study indicates that Mediterranean-Atlantic exchange is proportional to sill depth and the results of these simulations can therefore be used to interpret the Late Miocene sedimentary record both preceding and during the MSC Topper and Meijer (2015).…”

Section: Accepted Manuscriptmentioning

confidence: 99%

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Evolution of the Late Miocene Mediterranean–Atlantic gateways and their impact on regional and global environmental change

Flecker

Krijgsman

Capella

et al. 2015

Earth-Science Reviews

193

163

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Marine gateways play a critical role in the exchange of water, heat, salt and nutrients between oceans and seas. As a result, changes in gateway geometry can significantly alter both the pattern of global ocean circulation and associated heat transport and climate, as well as having a profound impact on local environmental conditions. Mediterranean-Atlantic marine corridors that pre-date the modern Gibraltar Strait, closed during the Late Miocene and are now exposed on land in northern Morocco and southern Spain. The restriction and closure of these Miocene connections resulted in extreme salinity fluctuations in the Mediterranean, leading to the precipitation of thick evaporites. This event is known as the Messinian Salinity Crisis (MSC). The evolution and closure of the Mediterranean-Atlantic gateways are a critical control on the MSC, but at present the location, geometry and age of these gateways is still highly controversial, as is the impact of changing Mediterranean outflow on Northern Hemisphere circulation. Here, we present a comprehensive overview of the evolution of the Late Miocene gateways and the nature of Mediterranean-Atlantic exchange as deduced from published studies focussed both on the sediments preserved within the fossil corridors and inferences that can be derived from data in the adjacent basins. We also consider the possible impact of evolving exchange on both the Mediterranean and global climate and highlight the main enduring challenges for reconstructing past Mediterranean-Atlantic exchange.

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Section: Accepted Manuscriptmentioning

confidence: 99%

“…Sill depths below 10 m result in blocked Mediterranean Outflow, which could represent a plausible scenario for the second stage of the MSC (Fig. 2), characterised by the rapid accumulation of halite in the Mediterranean (Topper and Meijer, 2015).…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Evolution of the Late Miocene Mediterranean–Atlantic gateways and their impact on regional and global environmental change

Flecker

Krijgsman

Capella

et al. 2015

Earth-Science Reviews

193

163

View full text Add to dashboard Cite

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“…First, variability within a precessional cycle remains difficult to resolve. Lourens et al () observed a ~3‐ky lag from precession minima to the midpoint of youngest Eastern Mediterranean sapropel S1 based on 14 C dating; similarly, Topper and Meijer () found that responses in a “typical” marginal Mediterranean basin may lag precession minima by ~3 ka. However, Weber and Tuenter () describe general circulation model results indicating there should be little to no time lag for precessional climate forcing at midlatitudes.…”

Section: Discussionmentioning

confidence: 88%

“…First, variability within a precessional cycle remains difficult to resolve. Lourens et al (1996) observed a~3ky lag from precession minima to the midpoint of youngest Eastern Mediterranean sapropel S1 based on 14 C dating; similarly, Topper and Meijer (2015) found that responses in a "typical" marginal Mediterranean basin may lag precession minima by~3 ka. However, Weber and Tuenter (2011) The leads and lags observed from data-based studies are partly due to the complex processes mediating sapropel deposition, the fact that these may not be identical in all parts of the Mediterranean region, and post-depositional changes.…”

Section: Potential Role Of Seawater Pb Isotopes In Mediterranean Astrmentioning

confidence: 88%

Precessional Cyclicity of Seawater Pb Isotopes in the Late Miocene Mediterranean

Modestou

Gutjahr

Schee

et al. 2019

Paleoceanog and Paleoclimatol

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Astronomical tuning in the Mediterranean region is primarily based on organically-mediated proxies, such as cyclicity of organic rich layers or changes in foraminiferal assemblages. Both during and post deposition, organic proxies can be affected by complex processes not immediately related to the changes in precession (insolation) they are assumed to reflect. Here we present an isotopic proxy which exhibits precessional cyclicity yet is inorganic. Seawater lead (Pb) isotope records over four precessional cycles between 6.6 and 6.5 Ma, from bulk sediment leachates of three Messinian, circum-Mediterranean marginal locations, show variations consistent with precessional cyclicity. During insolation minima, the Pb isotope signatures from all three sites converge to similar values, suggesting a regional process is affecting all three locations at that time. Data from the marginal sites are compared with new data from ODP Site 978 and published data from a variety of geological archives from the Mediterranean region to determine the mechanism(s) causing the observed variability. While the comparisons are not fully conclusive, the timing of events suggest that increased dust production from North Africa during insolation minima is the most likely control. This hypothesis implies that authigenic marine Pb isotope records have the potential to provide a reliable inorganic tie point for Mediterranean cyclostratigraphy where sub-precessional resolution is required. An inorganic tie point could also provide the means to resolve long-standing problems in Mediterranean stratigraphy on precessional and sub-precessional timescales which have been obscured due to post-depositional changes (e.g., sapropel burn-down) or suboptimal ecological conditions (e.g., the Messinian Salinity Crisis). Plain Language SummaryResearch into the geological and climate history of the Mediterranean region has been important globally, partly because the geologic timescale, back to about 23 million years ago, is pinned to the geological record of this region and partly because the water exiting the Mediterranean into the Atlantic is an important component of global ocean circulation. In this paper, we examine changes through time in the isotope ratios of the trace metal lead (Pb), which is present in tiny amounts even in unpolluted seawater. Our Pb isotope records, covering~100 thousand years at about 6.5 million years ago, show distinctive regular cyclicity with time, with "peaks" at approximately 20 thousand year intervals. We hypothesize that wet-dry climate cycles in North Africa produced these peaks by supplying more dust to the Mediterranean during the driest part of the cycle, when Pb from dust would have more strongly influenced the seawater Pb isotope composition. This hypothesis is exciting because it suggests that seawater Pb isotopes have the potential to improve our understanding of the passage of time in the Mediterranean region, in particular at times and locations where existing techniques are inadequate.

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“…For brevity, we will refer to the i direction as “east‐west” and j direction as “north‐south.” Starting with Zavatarelli and Mellor [], POM has been widely applied to investigate the oceanography of the Mediterranean Sea. Recently, sbPOM has been successfully used to study the Mediterranean circulation [ Topper and Meijer , ].…”

Section: Model Setupmentioning

confidence: 99%

Water exchange through the Betic and Rifian corridors prior to the Messinian Salinity Crisis: A model study

et al. 2015

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Although the present-day Mediterranean-Atlantic water exchange has been extensively studied, little is known about the dynamics of the Betic and Rifian corridors that existed before the Messinian Salinity Crisis. Due to the difficulties in studying the paleogeographic evolution of these corridors, physics-based knowledge of their behavior is essential to interpret observational evidence and to relate flow structures to gateway geometries. Here we present the first systematic model study of the water exchange through these gateways. We use the parallel version of the Princeton Ocean Model (sbPOM) and a set of idealized bathymetries based on a late Tortonian paleogeography. This analysis represents a major step forward in the understanding of the behavior of the double-gateway system constituted by the Late Miocene Betic and Rifian corridors. We demonstrate that the "siphon" scenario, involving inflow of cold upwelled Atlantic water through the Rifian corridor and outflow of Mediterranean water only via the Betic corridor, is unlikely from a physics perspective. It is shown that two exchange patterns are possible depending solely on the relative depth of the corridors. The implication of this is that geological evidence for the behavior of one corridor provides information about the dimensions of the other. We show that disappearance of outflow in one corridor does not necessarily imply its closure and we establish a guideline to determine how geological evidence can be interpreted as indicating one-or two-layer flow. Based on the model results, we propose new physics-based scenarios for the time interval defined for the siphon.

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Changes in Mediterranean circulation and water characteristics due to restriction of the Atlantic connection: a high-resolution ocean model

Cited by 14 publications

References 80 publications

Evolution of the Late Miocene Mediterranean–Atlantic gateways and their impact on regional and global environmental change

Evolution of the Late Miocene Mediterranean–Atlantic gateways and their impact on regional and global environmental change

Precessional Cyclicity of Seawater Pb Isotopes in the Late Miocene Mediterranean

Water exchange through the Betic and Rifian corridors prior to the Messinian Salinity Crisis: A model study

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