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

TLDR: In this paper, 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.

About: This article is published in Earth-Science Reviews.The article was published on 2015-11-01 and is currently open access. It has received 174 citations till now. The article focuses on the topics: Late Miocene.

Figures

Figure 6.

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Table 1. List of acronyms and their definitions used in this paper

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Full text

Flecker, R., Krijgsman, W., Capella, W., de Castro Martíns, C.,
Dmitrieva, E., Mayser, J. P., Marzocchi, A., Modestu, S., Ochoa, D.,
Simon, D., Tulbure, M., van den Berg, B., van der Schee, M., de
Lange, G., Ellam, R., Govers, R., Gutjahr, M., Hilgen, F.,
Kouwenhoven, T., ... Yousfi, M. Z. (2015). Evolution of the Late
Miocene Mediterranean-Atlantic gateways and their impact on
regional and global environmental change.
Earth-Science Reviews
,
150
, 365-392. [2154]. https://doi.org/10.1016/j.earscirev.2015.08.007
Peer reviewed version
Link to published version (if available):
10.1016/j.earscirev.2015.08.007
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 
Evolution of the Late Miocene Mediterranean-Atlantic gateways and their
impact on regional and global environmental change
Rachel Flecker, Wout Krijgsman, Walter Capella, Cesar de Castro Mart´ıns,
Evelina Dmitrieva, Jan Peter Mayser, Alice Marzocchi, Sevasti Modestu,
Diana Ochoa Lozano, Dirk Simon, Maria Tulbure, Bas van den Berg, Marlies
van der Schee, Gert de Lange, Robert Ellam, Rob Govers, Marcus Gutjahr,
Frits Hilgen, Tanja Kouwenhoven, Johanna Lofi, Paul Meijer, Francisco J.
Sierro, Naima Bachiri, Nadia Barhoun, Abdelwahid Chakor Alami, Beatriz
Chacon, Jose A. Flores, John Gregory, James Howard, Dan Lunt, Maria
Ochoa, Rich Pancost, Stephen Vincent, Mohamed Zakaria Yousfi
PII: S0012-8252(15)30031-3
DOI: doi: 10.1016/j.earscirev.2015.08.007
Reference: EARTH 2154
To appear in: Earth Science Reviews
Received date: 27 March 2015
Revised date: 24 July 2015
Accepted date: 19 August 2015
Please cite this article as: Flecker, Rachel,Krijgsman,Wout,Capella,Walter,deCas-
tro Mart´ıns, Cesar, Dmitrieva, Evelina, Mayser, Jan Peter, Marzocchi, Alice, Modestu,
Sevasti, Lozano, Diana Ochoa, Simon, Dirk, Tulbure, Maria, van den Berg, Bas, van
der Schee, Marlies, de Lange, Gert, Ellam, Robert, Govers, Rob, Gutjahr, Marcus,
Hilgen, Frits, Kouwenhoven, Tanja, Lofi, Johanna, Meijer, Paul, Sierro, Francisco J.,
Bachiri, Naima, Barhoun, Nadia, Alami, Abdelwahid Chakor, Chacon, Beatriz, Flores,
Jose A., Gregory, John, Howard, James, Lunt, Dan, Ochoa, Maria, Pancost, Rich, Vin-
cent, Stephen, Yousfi, Mohamed Zakaria, Evolution of the Late Miocene Mediterranean-
Atlantic gateways and their impact on regional and global environmental change, Earth
Science Reviews (2015), doi: 10.1016/j.earscirev.2015.08.007
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ACCEPTED MANUSCRIPT
ACCEPTED MANUSCRIPT
1
Evolution of the Late Miocene Mediterranean-Atlantic gateways and their impact on
regional and global environmental change
Rachel Flecker
1
, Wout Krijgsman
2
, Walter Capella
2
, Cesar de Castro Martín s
3
, Evelina
Dmitrieva
4
, Jan Peter Mayser
3
, Alice Marzocchi
1
, Sevasti Modestu
5
, Diana Ochoa Lozano
6
,
Dirk Simon
2
, Maria Tulbure
2
, Bas van den Berg
6
, Marlies van der Schee
6
, Gert de Lange
2
,
Robert Ellam
5
, Rob Govers
2
, Marcus Gutjahr
10
, Frits Hilgen
2
, Tanja Kouwenhoven
2
, Johanna
Lofi
12
, Paul Meijer
2
, Francisco J. Sierro
6
Naima Bachiri
7
, Nadia Barhoun
7
, Abdelwahid
Chakor Alami
8
, Beatriz Chacon
4
, Jose A Flores
6
, John Gregory
9
, James Howard
11
, Dan Lunt
1
,
Maria Ochoa
4
, Rich Pancost
3
, Stephen Vincent
11
, Mohamed Zakaria Yousfi
7
1 BRIDGE, School of Geographical Sciences and Cabot Institute, University of Bristol,
University Road, Bristol, BS8 1SS, UK
2 Department of Earth Sciences, Utrecht University, PO Box 80.021, 3508 TA, Utrecht,
The Netherlands
3 School of Chemistry and Cabot Institute, University of Bristol, Cantock's Close,
Bristol, BS8 1TS4, UK
4 REPSOL Exploración, S.A., Paseo de la Castellana 280, 4B-28046- Madrid, Spain
5 Scottish Universities Environmental Research Centre (SUERC), Scottish Enterprise
Technology Park, Rankine Ave., East Kilbride, G75 0QF UK
6 Department of Geology, University of Salamanca, Plaza de los Caídos s/n, 37008,
Salamanca, Spain
7 Université Hassan II Mohammedia, Fac Sci Ben MSik, Casablanca, Morocco
8 Office National des Hydrocarbures et des Mines, 5, Avenue Moulay Hassan, BP 99
Rabat, Morocco
9 PetroStrat Ltd, Tyttenhanger House, Tyttenhanger Park, St Albans, Hertfordshire,
UK, AL4 0PG.

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2
10 GEOMAR Helmholtz Centre for Ocean Research Kiel, Wischhofstrasse 1-3, 24148
Kiel, Germany
11 CASP, 181a Huntingdon Road, Cambridge, CB3 0DH, UK
12 Géosciences Montpellier, UMR5243, Université Montpellier II, 34090 Montpellier,
France, and Department of Geology / University of Leicester, Leicester LE1 7RH, UK
Abstract
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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3
Keywords: marine gateways, Mediterranean, Atlantic, climate, Messinian Salinity Crisis
1. INTRODUCTION
During the late Tortonian (~11.6 to 7.2 Ma), several marine gateways through southern
Spain, northern Morocco and potentially Gibraltar, connected the Mediterranean Sea with the
Atlantic Ocean (Fig. 1). Plate tectonic convergence between Africa and Iberia, combined
with subduction dynamics in the Alborán region, progressively closed these connections
during the Messinian (e.g. Duggen et al., 2003; Gutscher et al., 2002). This tectonic forcing
combined with eustatic (e.g. Manzi et al., 2013) and climatic (Hilgen et al., 2007) factors
resulted in a complex history of varied Mediterranean-Atlantic exchange and high amplitude
environmental fluctuations in the Mediterranean including the formation of the world‘s most
recent saline giant (Warren, 2010).
Like other marginal basins, the Mediterranean‘s near-landlocked configuration makes it
sensitive to subtle changes in climate (e.g. Thunell et al., 1988). Consequently, the first
environmental responses to gradual restriction of exchange with the Atlantic recorded in the
Mediterranean (e.g. faunal and isotopic changes; Fig. 2), predate any evaporite precipitation
there by a million years or more. The most extreme palaeoenvironmental changes took place
during the so-called Messinian Salinity Crisis (MSC; 5.97-5.33 Ma; Fig. 2; Table 1) when
extensive gypsum deposits precipitated in the Mediterranean‘s marginal basins and kilometre
thick halite units formed in the deep basins (e.g. Hsü et al., 1973; Ryan et al., 1973). This was
followed by a period during which the sediments recorded highly fluctuating conditions
varying from brackish to hypersaline, before returning, in the Early Pliocene, to open marine
conditions (Fig. 2; Hsü et al., 1972). These Late Miocene low salinity intervals, known as the
Lago Mare, may be the product of an additional freshwater source supplied to the
Mediterranean from Paratethys, the lacustrine precursor to the Black and Caspian seas. Like

Frequently asked questions

Q1. What are the contributions in this paper?

Here, the authors 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. The authors 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. 

Q2. What is the reason for the decline in Mediterranean planktic assemblages?

Decreasing abundances of Mediterranean planktic assemblages and a trend towards low diversity are attributed to increasingly adverse conditions of the surface waters preceding the MSC. 

Q3. What is the potential for higher resolution records?

Marine fossils such as fish remains, teeth or bone fragments and foraminifera are an alternative target for Nd isotopic measurements with the potential for much higher resolution records. 

Q4. What is the mechanism for achieving low salinity conditions in the Mediterranean?

TThe mechanisms for achieving very low salinity conditions in the Mediterranean are either substantial dilution by fresh water from Paratethys (Orszag-Sperber, 2006; Rouchy and Caruso, 2006; Roveri et al., 2008) and/or a change in climate leading to a switching of the Mediterranean‘s hydrologic budget from negative to positive (Gladstone et al., 2007). 

Q5. What was the first thought that the North Betic Strait was open throughout the Messinian?

Müller and Hsü (1987) initially suggested that the North Betic strait was open throughout the Messinian, allowing an ocean water flux and providing the salt required for evaporite deposition to reach the Mediterranean. 

Q6. Why is the only direct access to part of the MSC through Sicily?

Because the deep basinal halite has not been drilled, the only direct access to part of this succession is through a mine on Sicily. 

Q7. What are the main methods used to reconstruct palaeo-water depths?

Several methods based on microfossils have been used to reconstruct palaeo-water depths, including (1) the ratio between planktic and benthic foraminifera (P/B ratios), (2) the occurrence of benthic foraminiferal species with restricted depth ranges that are assumed to be constant (e.g. Van Hinsbergen et al., 2005), and (3) transfer functions (e.g. Van der Zwaan et al., 1990; Hohenegger, 2005; Baldi & Hohenegger, 2008). 

Q8. What is the extreme divergence between the planktic and benthic communities?

The most extreme divergence between the planktic and benthic communities on the Mediterranean and Atlantic sides of the corridors is associated with the onset of evaporite deposition at 5.971 Ma (Manzi et al., 2013), when marine organisms disappear from the Mediterranean. 

Q9. How does Meijer (2006) show that in order to reach MSC saturations levels the exchange?

As to the magnitude of the exchange fluxes, Meijer (2006) shows that in order to reach MSC saturations levels the exchange fluxes have to reduce to a few percent relative to modern values. 

Q10. What is the resulting deviation from the seawater curve?

Tage carbonate or igneous rock both of which have low 87 Sr/ 86 Sr ratios (e.g. Albarede and Michard, 1987; Flecker and Ellam, 1999; Schildgen et al., 2014), the resulting deviation would be towards values lower than those expected from the seawater curve for the age of deposition (McArthur et al., 2001). 

Q11. What is the obvious contender as an additional water source?

The obvious contender as an additional water source is Paratethys, with its low Sr isotope ratio (Flecker and Ellam, 2006; Major et al., 2006) and brackish water salinity and fauna. 

Q12. What is the origin of the thrust belts?

These thrust belts are mostly the remnants of the Iberian and Nubian (African) passive margins that were deformed by thin-skinned folding and thrusting during the Miocene (Fig. 1 insert). 

Q13. How can the authors combine GCMs with regional ocean-only models?

This can be achieved by forcing ocean-only models with output from fully-coupled global simulations, and then running them at sufficiently high resolution to resolve more realistically the different gateway scenarios.