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

Abstract

The 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.

Mixed carbonate-siliciclastic contourite drift deposits associated with the entrance of an Atlantic-Mediterranean corridor (late Miocene, southwest Spain)

“…The occurrence of AIW through the Rifian Corridors during the Miocene has been repeatedly reported (Fig. 11A; Flecker et al, 2015;Capella et al, 2018;Ng et al, 2021) et al, 2011, 2014Ercilla et al, 2002). This can be an analogue for the opposite directions observed in the Osuna Drift and its coeval deposits in the Guadalhorce Corridor.…”

“…During the Miocene, however, the circulation of the two water masses, the MOW and the AIW, was not concentrated through the Strait of Gibraltar but distributed in complex system of corridors in the southern part of the Iberian Peninsula, the Betic corridors, and in the northern part of Morocco, the Rifian corridors (Martín et al, 2001(Martín et al, , 2009(Martín et al, , 2014Flecker et al, 2015;Capella et al, 2018;Krijgsman et al, 2018;Ng et al, 2021). The water exchange between the Mediterranean and the Atlantic during the early Messinian was characterised by AIW inflow through the Rifian corridors and MOW outflow through the Guadalhorce Corridor (Benson et al, 1991;Pérez-Asensio et al, 2012;Flecker et al, 2015;Krijgsman et al, 2018).…”

“…The nearly complete separation of the Mediterranean from the Atlantic Ocean during the late Miocene (Martín et al, 2001(Martín et al, , 2009(Martín et al, , 2010Betzler et al, 2006;Flecker et al, 2015;Tulbure et al, 2017;Capella et al, 2018;Ng et al, 2021) had a global impact on the thermohaline ocean circulation and, consequently, on the climate and organic matter fluxes (Pérez-Asensio et al, 2012, 2014Jiménez-Moreno et al, 2013). In the Betic Cordillera, several straits connected the Mediterranean and the Atlantic throughout the Guadalquivir Basin (Martín et al, 2001(Martín et al, , 2009(Martín et al, , 2014Betzler et al, 2006;Puga-Bernabéu et al, 2022).…”

Evolution of Ocean Circulation in the North Atlantic Ocean During the Miocene: Impact of the Greenland Ice Sheet and the Eastern Tethys Seaway

“…(2013)). We note incidentally that changes in the Gibraltar gateway configuration have been suggested to impact the AMOC later in the Miocene (Capella et al., 2019; Flecker et al., 2015; Ivanovic et al., 2013; Ng et al., 2021). In contrast, the modeling study of Z. Zhang et al.…”

“…In particular, even though the ETS is shallower in our simulation than in Hamon et al (2013), the flux through Gibraltar toward the Atlantic Ocean is higher (4 vs. 2.8 Sv in Hamon et al (2013)) because the Gibraltar gateway is deeper in our paleogeography (1,350 m vs. 400 m in Hamon et al (2013)). We note incidentally that changes in the Gibraltar gateway configuration have been suggested to impact the AMOC later in the Miocene (Capella et al, 2019;Flecker et al, 2015;Ivanovic et al, 2013;Ng et al, 2021). In contrast, the modeling study of Z.…”