Persistent monsoonal forcing of Mediterranean Outflow Water dynamics during the late Pleistocene

Geology ◽  
2015 ◽  
Vol 43 (11) ◽  
pp. 951-954 ◽  
Author(s):  
A. Bahr ◽  
S. Kaboth ◽  
F.J. Jiménez-Espejo ◽  
F.J. Sierro ◽  
A.H.L. Voelker ◽  
...  
Keyword(s):  
Late Pleistocene ◽  
Water Dynamics ◽  
Mediterranean Outflow Water ◽  
Mediterranean Outflow

scholarly journals Mediterranean Outflow Water dynamics during the past ~570 kyr: Regional and global implications

2017 ◽  
Vol 32 (6) ◽  
pp. 634-647 ◽  
Author(s):  
Stefanie Kaboth ◽  
Bas de Boer ◽  
André Bahr ◽  
Christian Zeeden ◽  
Lucas J. Lourens
Keyword(s):  
Water Dynamics ◽  
The Past ◽  
Mediterranean Outflow Water ◽  
Mediterranean Outflow

scholarly journals Latest Miocene restriction of the Mediterranean Outflow Water: a perspective from the Gulf of Cádiz

2021 ◽  
Vol 41 (2) ◽  
Author(s):  
Zhi Lin Ng ◽  
F. Javier Hernández-Molina ◽  
Débora Duarte ◽  
Francisco J. Sierro ◽  
Santiago Ledesma ◽  
...  
Keyword(s):  
Mass Exchange ◽  
Water Mass ◽  
Atlantic Water ◽  
Meridional Overturning Circulation ◽  
Gulf Of Cadiz ◽  
Mediterranean Outflow Water ◽  
Gulf Of Cádiz ◽  
Mediterranean Outflow ◽  
The Mediterranean ◽  
Water Mass Exchange

AbstractThe Mediterranean-Atlantic water mass exchange provides the ideal setting for deciphering the role of gateway evolution in ocean circulation. However, the dynamics of Mediterranean Outflow Water (MOW) during the closure of the Late Miocene Mediterranean-Atlantic gateways are poorly understood. Here, we define the sedimentary evolution of Neogene basins from the Gulf of Cádiz to the West Iberian margin to investigate MOW circulation during the latest Miocene. Seismic interpretation highlights a middle to upper Messinian seismic unit of transparent facies, whose base predates the onset of the Messinian salinity crisis (MSC). Its facies and distribution imply a predominantly hemipelagic environment along the Atlantic margins, suggesting an absence or intermittence of MOW preceding evaporite precipitation in the Mediterranean, simultaneous to progressive gateway restriction. The removal of MOW from the Mediterranean-Atlantic water mass exchange reorganized the Atlantic water masses and is correlated to a severe weakening of the Atlantic Meridional Overturning Circulation (AMOC) and a period of further cooling in the North Atlantic during the latest Miocene.

scholarly journals Mediterranean Outflow Water variability during the Early Pleistocene climate transition

2017 ◽  
Author(s):  
Stefanie Kaboth ◽  
Patrick Grunert ◽  
Lucas J. Lourens
Keyword(s):  
North Atlantic ◽  
Early Pleistocene ◽  
Time Interval ◽  
Intermediate Water ◽  
Mediterranean Outflow Water ◽  
The North ◽  
Pleistocene Climate ◽  
Mediterranean Outflow ◽  
The North Atlantic ◽  
Climate Transition

Abstract. Gaining insights into the evolution of Mediterranean Outflow Water (MOW) during the Early Pleistocene climate transition has been so far hampered by the lack of available paleoclimatic archives. Here we present the first benthic foraminifera stable oxygen and carbon isotope records and grain-size data from IODP Expedition 339 Site U1389 presently located within the upper core of the MOW in the Gulf of Cadiz for the time interval between 2.6 and 1.8 Ma. A comparison with an intermediate water mass record from the Mediterranean Sea strongly suggest an active MOW supplying Site U1389 on glacial-interglacial timescales during the Early Pleistocene. We also find indication that the increasing presence of MOW in the Gulf of Cadiz during the investigated time interval aligns with the progressive northward protrusion of Mediterranean sourced intermediate water masses into the North Atlantic, possibly modulating the intensification of the North Atlantic Meridional Overturning Circulation at the same time. Additionally, our results suggest that MOW flow strength was already governed by precession and semi-precession cyclicity during the Early Pleistocene against the background of glacial-interglacial variability dominated by the obliquity cycle of Earth`s inclination axis.

scholarly journals Regional circulation patterns of Mediterranean Outflow Water near the Iberian and African continental slopes

Ocean Science ◽  
2019 ◽  
Vol 15 (3) ◽  
pp. 565-582
Author(s):  
Álvaro de Pascual-Collar ◽  
Marcos G. Sotillo ◽  
Bruno Levier ◽  
Roland Aznar ◽  
Pablo Lorente ◽  
...  
Keyword(s):  
High Resolution ◽  
North Atlantic ◽  
Water Mass ◽  
Intermediate Water ◽  
Mixing Processes ◽  
Surrounding Water ◽  
Mediterranean Outflow Water ◽  
Circulation Patterns ◽  
Continental Slopes ◽  
Mediterranean Outflow

Abstract. The Mediterranean Outflow Water (MOW) is a dense water mass originated in the Strait of Gibraltar. Downstream of the Gulf of Cádiz, the MOW forms a reservoir region west of the Iberian continental slopes at a buoyant depth of approximately 1000 m. This region plays a key role as the main centre where the MOW is mixed and distributed into the North Atlantic. The seafloor in this area is characterized by the presence of a complex bathymetry with three abyssal plains separated by mountain chains. Although the topographic features do not reach the surface, they influence ocean flows at intermediate and deep ocean layers, conditioning the distribution and circulation of MOW. The Copernicus Marine Environmental Monitoring Service (CMEMS) Iberian–Biscay–Ireland (IBI) ocean reanalysis is used to provide a detailed view of the circulation and mixing processes of MOW near the Iberian and African continental slopes. This work emphasizes the relevance of the complex bathymetric features defining the circulation processes of MOW in this region. The high resolution of the IBI reanalysis allows us to make a description of the mesoscale features forced by the topography. The temperature, salinity, velocity, transport, and vorticity fields are analysed to understand the circulation patterns of MOW. The high-resolution circulation patterns reveal that Horseshoe Basin and the continental slope near Cape Ghir (a.k.a. Cap Rhir or Cabo de Aguer) are key areas controlling the mixing processes of MOW with the surrounding water masses, mainly North Atlantic Central Water (NACW) and Antarctic Intermediate Water (AAIW). The water mass variability is also analysed by means of composite analysis. Results indicate the existence of a variability in the MOW tongue which retracts and expands westwards in opposition to the movement of the underlying North Atlantic Deep Water.

Benthic foraminifera as tools to distinguish contourites and turbidites

2021 ◽  
Author(s):  
Johanna Schmidt ◽  
Anna Saupe ◽  
Jassin Petersen ◽  
André Bahr ◽  
Patrick Grunert
Keyword(s):  
Diagnostic Criteria ◽  
Coarse Grained ◽  
Bottom Current ◽  
Gulf Of Cadiz ◽  
Sedimentary Processes ◽  
Bottom Currents ◽  
Mediterranean Outflow Water ◽  
Gulf Of Cádiz ◽  
Mediterranean Outflow ◽  
Del Rio

<p>Contourites occur where along-slope bottom currents induce large accumulations of sediments in the deep sea (Faugères and Stow, 2008). Distinguishing among contourites and other depositional facies on continental slopes is fundamental for paleoenvironmental reconstructions like bottom current velocities. Nonetheless, reliable and easily applicable diagnostic criteria to properly differentiate between contourites and other coarse-grained and/or graded deep-water deposits such as turbidites are still sparse (e.g., de Castro et al., 2020). The differentiation and interpretation of these deposits is particularly complex in areas where downslope and along-slope sedimentary processes co-occur.</p><p>The SW Iberian Margin represents an ideal natural laboratory to study the complex interaction of downslope and along-slope processes. Persistent bottom current activity of Mediterranean Outflow Water (MOW) since the early Pliocene (García-Gallardo et al., 2017) resulted in the deposition of thick contourite drift bodies in the Gulf of Cádiz (Hernández-Molina et al., 2014). At the same time, downslope transport, channeled through submarine canyons, occurs frequently. Extensive turbidite intervals - intercalated between contouritic layers and often reworked by bottom currents - have been identified in several Pleistocene and Pliocene sediments in this area (Stow et al., 2013).</p><p>The aim of this study is to define diagnostic criteria to differentiate normally graded contourites and turbidites as well as reworked turbidites based on microfaunal analyses. Benthic foraminiferal assemblages along Pleistocene contouritic (~0.5 Ma) and turbiditic (~0.9 Ma, ~1.1 Ma) sequences in the Gulf of Cádiz (IODP Site U1389) are evaluated to test if their faunal composition provides a reliable tool to distinguish these deposits and the underlying sedimentary processes.</p><p> </p><p> </p><p> </p><p>References:</p><p>de Castro, S., Hernández-Molina, F.J., de Weger, W., Jiménez-Espejo, F.J., Rodríguez-Tovar, F.J., Mena, A., Llave, E., Sierro, F.J., 2020. Contourite characterization and its discrimination from other deep‐water deposits in the Gulf of Cadiz contourite depositional system. Sedimentology. https://doi.org/10.1111/sed.12813</p><p>Faugères, J.C., Stow, D.A.V., 2008. Contourite Drifts. Nature, Evolution and Controls. Dev. Sedimentol. 60, 257–288. https://doi.org/10.1016/S0070-4571(08)10014-0</p><p>García-Gallardo, Á., Grunert, P., Voelker, A.H.L., Mendes, I., Piller, W.E., 2017. Re-evaluation of the “elevated epifauna” as indicator of Mediterranean Outflow Water in the Gulf of Cadiz using stable isotopes (δ13C, δ18O). Glob. Planet. Change 155, 78–97. https://doi.org/10.1016/j.gloplacha.2017.06.005</p><p>Hernández-Molina, F.J., Llave, E., Preu, B., Ercilla, G., Fontan, A., Bruno, M., Serra, N., Gomiz, J.J., Brackenridge, R.E., Sierro, F.J., Stow, D.A.V., García, M., Juan, C., Sandoval, N., Arnaiz, A., 2014. Contourite processes associated with the Mediterranean Outfl ow Water after its exit from the Strait of Gibraltar: Global and conceptual implications. Geology 42, 227–230. https://doi.org/10.1130/G35083.1</p><p>Stow, D.A.V., Hernández-Molina, F.J., Llave, E., Bruno, M., García, M., Díaz del Rio, V., Somoza, L., Brackenridge, R.E., 2013. The Cadiz Contourite Channel: Sandy contourites, bedforms and dynamic current interaction. Mar. Geol. 343, 99–114. https://doi.org/10.1016/j.margeo.2013.06.013</p>

Reconstructions of the Mediterranean Outflow Water during the quaternary based on the study of changes in buried mounded drift stacking pattern in the Gulf of Cadiz

2007 ◽  
Vol 28 (4) ◽  
pp. 379-394 ◽  
Author(s):  
Estefania Llave ◽  
Francisco J. Hernández-Molina ◽  
Dorrik A. V. Stow ◽  
Mari Carmen Fernández-Puga ◽  
Margarita García ◽  
...  
Keyword(s):  
Gulf Of Cadiz ◽  
Mediterranean Outflow Water ◽  
Stacking Pattern ◽  
Gulf Of Cádiz ◽  
Mediterranean Outflow ◽  
The Mediterranean
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