https://doi.org/10.1130/G47944.1

Manuscript received 19 February 2020 Revised manuscript received 27 May 2020 Manuscript accepted 8 July 2020

© 2020 The Authors. Gold Open Access: This paper is published under the terms of the CC-BY license. Published online 13 August 2020

Late Miocene system reveals intermittent overflow behavior Wouter de Weger1*, F. Javier Hernández-Molina1, Rachel Flecker2, Francisco J. Sierro3, Domenico Chiarella1, Wout Krijgsman4 and M. Amine Manar5 1Department of Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK 2Bristol Research Initiative for the Dynamic Global Environment (BRIDGE), University of Bristol, University Road, Bristol BS8 1SS, UK 3Department of , University of Salamanca, 37008, Salamanca, Spain 4Department of Earth Sciences, Utrecht University, P.O. Box 80.021, 35008 TA Utrecht, Netherlands 5Office National des Hydrocarbures et des Mines (ONHYM), 34, Avenue Al Fadila, BP 99 Rabat, Morocco

ABSTRACT Rifian Corridor, Morocco. These channels are Paleoceanographic information from submarine overflows in the vicinity of oceanic gate- associated with the late Miocene paleo-MOW, ways is of major importance for resolving the role of circulation in modulating Earth’s which played an important role in water-mass . Earth system models are currently the favored way to study the impact of gateways exchange with the Atlantic Ocean (Seidenkrantz on global-scale processes, but studies on overflow-related deposits are more suitable to under- et al., 2000). stand the detailed changes. Such deposits, however, had not yet been documented in . Here, we present a unique late Miocene contourite channel system from the Rifian Corridor REGIONAL SETTING (Morocco) related to the initiation of Mediterranean Outflow Water (MOW). Two channel The South Rifian Corridor is part of the Rif- branches were identified consisting of three vertically stacked channelized units Betic Cordillera, an arc-shaped encased in muddy deposits. Both branches have different channel-fill characteristics. Our surrounding the Alborán in the western- findings provide strong evidence for intermittent behavior of overflow controlled by tectonic most part of the Mediterranean (Fig. 1). This processes and regional climatic change. These fluctuations in paleo-MOW intermittently marine gateway evolved in the Tortonian as a influenced global ocean circulation. southwestward-migrating foreland basin during the latest stage of Africa-Iberia collision (Sani INTRODUCTION these models are not suited to simulate hydraulic et al., 2007). The main basins that recorded sedi- Plate-tectonic reconfiguration plays a major controls of narrow gateways, generating results mentation are the Saiss-Gharb on the Atlantic role in modifying global ocean circulation and that differ from observations (Alhammoud et al., side and the Taza-Guercif on the Mediterranean poleward temperature gradients by opening 2010; Ivanovic et al., 2013). To reconstruct the side of the paleo–Taza (Fig. 1; Capella et al., and closing oceanic gateways (Knutz, 2008). detailed timing and nature of changing connec- 2017a). The studied sections are situated just Changes in the transport of saline Mediterra- tivity, a geological record is required. Critical north of the Saiss Basin, where the seafloor mor- nean Outflow Water (MOW) to northern lati- information for reconstructing gateway over- phology contained subaqueous highs formed by tudes are no exception, as the present-day MOW flows is most likely preserved in the the Prerif (“PR” in Fig. 1; Roldán et al., contributes to the Atlantic Meridional Overturn- that accumulated at its exit, i.e., 2014) and the imbricate wedge (Prerifian Nappe ing Circulation by as much as 15%, increasing (e.g., Toucanne et al., 2007). in Capella et al., 2017a). The frontal part of this the North Atlantic surface temperature by 1 °C Contourite features have been recognized in wedge forms the northern slope of the corridor, (Rogerson et al., 2012). The occurrence of a modern and ancient sedimentary records along which consists of intraslope subbasins related late Miocene paleo-MOW therefore likely had continental margins and in deep-water settings. to the main thrust faults. an impact on global ocean circulation and asso- Despite growing scientific interest, these deep- ciated climate change. Recently, Capella et al. marine systems remain relatively poorly under- SEDIMENTARY RECORD (2019) suggested that initiation of this paleo- stood (Rebesco et al., 2014; Stow and Smillie, We identified eight facies (F1–F8) associ- MOW contributed to both the δ13C shift and 2020), since very few ancient contourite depos- ated with hemipelagic, gravitational, and con- global cooling. its have been identified in and cores tourite deposits (Table S1 in the Supplemental General circulation models are regularly (Hüneke and Stow, 2008; Mutti et al., 2014). ­Material1). The Sidi Chahed section corresponds used to reconstruct the nature of changing con- Here, we describe an unprecedented archive to “Ben Allou” studied by Capella et al. (2017a), nectivity between and . However, for unravelling the initial stages of MOW and while the Kirmta section is newly recognized. the controls on overflow behavior based on Both sections are composed of three verti- *E-mail: [email protected] two ancient contourite channels in the former cally stacked sandstone units consisting of a

1Supplemental Material. Table S1 (facies and facies association scheme with example pictures from the outcrops). Please visit https://doi.org/10.1130/GEOL.S.12730928​ to access the supplemental material, and contact [email protected] with any questions.

CITATION: de Weger, W., et al., 2020, Late Miocene contourite channel system reveals intermittent overflow behavior: Geology, v. 48, p. 1194–1199, https://doi​ .org/10.1130/G47944.1

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Downloaded from http://pubs.geoscienceworld.org/gsa/geology/article-pdf/48/12/1194/5186221/1194.pdf by guest on 27 September 2021 into the Saiss Basin, generating a dense paleo- MOW that was deflected to the right (north- 7 W6 W5 W4 W3 W 1 W northeast) by the force. 37 N The main sandstone units are interpreted orridors as contourite channel fills, part of an extensive Study area Betic C contourite channel system. The interaction with Cádiz Malaga partially incised, interstratified slump deposits Present day (Fig. 2C), and the co-occurrence of shallow- and 36 N MOW Gibraltar Strait Alboran SSeeaa deep-marine bioclastic and foraminiferal assem- blages that were subsequently reworked and accumulated within the along-slope channels by bottom currents all serve as evidence for an up-slope source. Additional evidence 35 N of and sediment supply lies in the pres- paleo- Kirmta ence of middle Miocene white marls (Figs. 2 rn RC and 3; Sani et al., 2007) and bipyrami- MOW he ort C N R dal of the facies (Herrero et al., rn Fig. 4 he RABAT Sout 2020), which was incorporated in the imbricate N 34 N PR wedge. These sediments were sourced by both Fes AFRICA Taza-sill down- and along-slope processes, whereas ero- Sidi Chahed 100 km sion was induced by bottom currents. Foraminifer assemblages, similar for both Basins Cities Gharb Saiss Taza-Guercif Frontal part Imbricate Wedge sites, indicate that deposition of the Sidi Chahed Figure 1. Paleogeographic reconstruction of the late Miocene western Mediterranean (modified and Kirmta sections occurred between 7.8 and after Capella et al., 2017a). Gray—subaqueous Prerif Ridges (PR). Red (lower) and orange (upper) 7.51 Ma (Capella et al., 2017a). Despite coeval arrows depict Mediterranean Outflow Water (MOW) branches. Globe shows MOW (orange) and activity, both sections show morphological dif- main surficial (red) and deep-water circulation patterns (blue). Map data are ©2018 Google™ ferences in channel geometry and channel fill with topographic overlay from U.S. Geological Survey topographic maps (http://earthpoint.us/ TopoMap.aspx). related to different hydrodynamic properties (deeply incised, narrow channels filled by 3-D and 2-D and interstratified slump deposits ­compositional mix (sensu Chiarella et al., 2017) directions that are almost perpendicular to the in Sidi Chahed versus shallow, wide channels of bioclastic (dominantly shell, echinoid, and main trends of the dunes (Figs. 2 and 3) and are filled by 2-D dunes in Kirmta). Hydrodynamic bryozoan fragments and foraminifera) and very subparallel to the southwest-directed paleoslope. differences are also observed from the differ- fine– to coarse-grained . These Paleodepth estimates from benthic foramin- ences in sand/marl ratios. Based on bed-form sandstone units are encased in muddy sediments ifera indicate a physiographic domain between types (F3, F4, and F5) and their characteristics (F1 and F2), resulting in a sand/marl ratio of 150 and 400 m water depth, equivalent to an (Table S1; Stow et al., 2009), Sidi Chahed was 0.73 for Sidi Chahed and 0.42 for Kirmta. outer shelf to upper/middle continental slope influenced by higher-velocity bottom currents In the Sidi Chahed section, the sandstone (Capella et al., 2017a). The tectonically con- (up to 1 m s−1) compared to Kirmta (<0.5 m s−1). units form the infill of large (roughly 500 m fined corridor and proximal location to the By comparison with the present-day MOW wide), up to 40-m-deep incisions (Fig. 2). Sub- gateway resulted in steep margins (Longhi- through the Gibraltar gateway, the proximal ordinate incisions (20–300 m wide) are filled tano, 2013) prone to gravitational depositional sector of the Gulf of Cádiz contourite system (Fig. 2) by compound (up to meter-scale) three- processes. (GoCCS; Fig. 1) also has two main channels dimensional (3-D) dunes (F5), two-dimensional occupying the middle slope at different depths dunes (F4), and slump deposits (F6). DECODING THE PALEO-MOW due to the circulation of the lower and upper Sandstone units in the Kirmta section are the The investigation of the Kirmta outcrop branches of the MOW (Hernández-Molina et al., infill of wider (>1 km) and shallower (5–15 m) allowed us, for the first time, to analyze the 2014). The similarities in geographic and depo- incisions compared to Sidi Chahed (Fig. 3). spatial distribution and time variations between sitional setting, channel distribution, and large These units consist of stacked 2-D dunes (up both sections. This new information enhanced morphological elements between the GoCCS to 60 cm in thickness, F4). The two lowermost the paleogeographic reconstruction, sedimento- and the Rifian Corridor indicate that hydrody- units are preceded by bigradational (- to fine logical interpretation, and understanding of the namic and feedback processes associated with sand–sized) planar bedsets (F3) with an average hydrodynamic setting. the MOW acted in a similar way. It is envisaged bed thickness of 10 cm and a lateral continu- Sidi Chahed and Kirmta, located 10 km that bifurcation of the paleo-MOW, similar to ity exceeding 3 km (Fig. 3B). In both sections, apart, are situated ∼120 km west of the paleo– the flow bifurcation recognized in the Gulf of the main sandstone intervals are bounded at the Taza Sill (Fig. 1), where they occupy a position Cadiz (Hernández-Molina et al., 2014), took base and top by and occasionally by against the main thrust zone. The paleo– place in the Saiss Basin, separating the paleo- debris-flow deposits (F7 and F8, respectively; Taza Sill was a submerged high controlling MOW into two branches that occupied differ- Figs. 2 and 3). Atlantic-Mediterranean water exchange in the ent depths along the slope of the corridor. The , mainly measured from cross- late Miocene (Capella et al., 2017a). The system lower branch (Sidi Chahed) occupied the deeper bedding, indicate a dominant westward direc- is thought to have acted in a similar way as the southern subbasin, and the upper branch (Kir- tion for the Sidi Chahed and a northwestward present-day MOW at the Camarinal Sill in the mta) occupied the shallower northern subbasin direction for the Kirmta sections (Figs. 2 and 3). Strait of Gibraltar (Baringer and Price, 1999; (Fig. 4). Gravity-driven deposits, such as (F7) Legg et al., 2009), where Mediterranean water Studies in the GoCCS (Baringer and Price, and slump deposits (F6), show was able to flow over and cascade down the sill 1999; Legg et al., 2009) have also shown that

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Downloaded from http://pubs.geoscienceworld.org/gsa/geology/article-pdf/48/12/1194/5186221/1194.pdf by guest on 27 September 2021 Figure 2. Sedimentary log, panoramic pictures, and interpretations for the Sidi Chahed section (Morocco; 34.101566°N, 5.301466°W). Three sand units (from old to young; yellow, green, and red) represent channel-fill sequences. Rosette dia- gram shows paleocurrent directions. (A) Basal fill sequence of sandstone unit 1. (B) Typical stack- ing pattern of facies F4. (C) Two bedsets of facies F4 separated by F6. Beds below F6 show soft-sediment deforma- tion, and overlying beds are erosive. Note near- perpendicular difference in paleocurrent direc- tions. (D) with mixed composi- tional sand of facies F4, and transported, exsolved (Dol) rhomb.

the MOW consists of the vertical distribution CONTROLS ON OVERFLOW mittency of the paleo-MOW was controlled by of three Mediterranean water masses (Modified The occurrence of two channel branches con- different hydrodynamic processes acting at dif- Atlantic Water, Levantine Intermediate Water, sisting of three vertically stacked sandstone units ferent physical and time scales. and Mediterranean Deep Water; e.g., GRIDA, encased in muddy deposits, with different chan- 2013). The bifurcation of the MOW into two nel-fill characteristics for each branch, provides Tectonic Processes branches, upper (MU) and lower (ML) MOW strong evidence for an intermittent behavior of Two important tectonic events are recorded (Hernández-Molina et al., 2014), is the result of the paleo-MOW during the late Tortonian. This in the late Miocene (Capella et al., 2017b): partial mixing of intermediate and deep Medi- intermittency is also evident from (1) subordi- (1) a regional compressional event around terranean waters. Consequently, we can infer nate erosional features that indicate migration 8.4–7.8 Ma, culminating in the emplacement a similar vertical distribution of water masses and/or reactivation of the bottom current cores, of the imbricate wedge just before the onset of in the Mediterranean during the late Miocene, (2) alternating changes in morphology and contourite deposition, and (2) the transition from which agrees with numerical models proposed sediment characteristics, and (3) tidal signatures thin- to thick-skinned contraction, which hap- by de la Vara et al. (2015). (Capella et al., 2017a). This indicates that inter- pened around the Tortonian-­Messinian ­boundary.

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Downloaded from http://pubs.geoscienceworld.org/gsa/geology/article-pdf/48/12/1194/5186221/1194.pdf by guest on 27 September 2021 Figure 3. Sedimentary log (see Fig. 2 for legend), panoramic pictures, and interpretations for the Kirmta section (Morocco; 34.170855°N, 5.239288°W). Rosette diagram shows paleocurrent directions. (A–B) Facies F3. (C) Sand- stone unit 2 with tabular cross-stratified beds (F4). (D–E) Facies F6, with ­turbidite deposits below uppermost sandstone unit.

Interestingly, between these two major tectonic tions. Particularly, the reconfiguration of the sill an increase in the density of Mediterranean Deep events, a period of relative tectonic quiescence would have significantly impacted the dynamics Water and intensification of the MOW (Llave occurred from ca. 7.8 to 7.25 Ma, coinciding of Mediterranean-Atlantic water exchange and et al., 2006). This implies that the MOW favors with the development of the recognized con- thus the behavior of the paleo-MOW. either the upper or lower channel based on its tourite channel system. Nevertheless, the north- density characteristics because of tectonic- and eastward, upslope migration of the three stacked Climatic Processes climatic-induced effects on the Mediterranean contourite channels, observed from the channel A relationship between long- and short- water masses. The late Miocene was not severely axis distribution in the outcrops (Figs. 2 and term climatic processes and the activity of the influenced by eccentricity (glacial-interglacial) 3), suggests that the imbricate wedge was tec- paleo-MOW is recognized at different scales, cycles but was dominated by precession (e.g., tonically active and migrated southwestward, but the lack of high-resolution age constraints Sierro et al., 1999). Precessional cyclicity intermittently affecting the evolution of the hampers our ability to provide detailed evidence was therefore likely the driving force behind depositional system. These tectonic processes of the dynamics between the upper and lower the intermittent behavior of the paleo-MOW. likely increased downslope sediment supply paleochannels. Observations from the GoCCS Smaller-order changes in the hydrodynamic by creating slope instability. Additionally, they show that a stronger MOW in the deeper channel characteristics of the overflow are likely related might have been responsible for channel migra- is linked to glacial periods, which are associated to millennial and seasonal changes in climatic tion resulting from slope and sill reconfigura- with higher aridity in the Mediterranean and thus conditions (e.g., Gladstone et al., 2007).

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Downloaded from http://pubs.geoscienceworld.org/gsa/geology/article-pdf/48/12/1194/5186221/1194.pdf by guest on 27 September 2021 Figure 4. Paleogeo- graphic model of the late Miocene Rifian Corridor (Morocco) with lower (red) and upper (orange) branches of paleo–Medi- terranean Outflow Water (MOW). Cross section A-A′ shows intraslope subba- sins that act as fairways in the frontal part of the imbricate wedge and are filled by three vertically stacked, color-labeled (1–3) sand units. Circles depict location of core for each paleo-MOW branch.

IMPACT ON THERMOHALINE shows that intermittency is possible on such Capella, W., Flecker, R., Hernández-Molina, F.J., CIRCULATION time scales, and more evidence of such behavior Simon, D., Meijer, P.T., Rogerson, M., Sierro, F.J., and Krijgsman, W., 2019, Mediterranean The late Miocene overflow was modulated should be obtained from similar systems, such isolation preconditioning the Earth system by a complex hierarchy and interplay of pro- as the Denmark Straits, Faroe Bank Channel, for late Miocene climate cooling: Scientific cesses. Studies across the Strait of Gibraltar have Red Sea, and Gulf of Cadiz. Reports, v. 9, p. 3795, https://doi​.org/10.1038/ also demonstrated that overflow processes are s41598-019-40208-2. Chiarella, D., Longhitano, S.G., and Tropeano, M., affected by a variety of control factors at dif- ACKNOWLEDGMENTS 2017, Types of mixing and heterogeneities in ferent scales (e.g., Schönfeld and Zahn, 2000; We thank Sonya Legg (Princeton University, Princ- siliciclastic-carbonate sediments: Marine and Llave et al., 2006). This indicates that under- eton, New Jersey) for her review and contribution in Petroleum Geology, v. 88, p. 617–627, https:// standing these late Miocene fossil contourite improving the manuscript before submission, and G. doi​.org/10.1016/​j.marpetgeo.2017.09.010. Davoli and two anonymous reviewers for their posi- deposits can significantly help us to better under- de la Vara, A., Topper, R.P., Meijer, P.T., and Kou- tive suggestions and comments. Furthermore, we are wenhoven, T.J., 2015, Water exchange through stand changes in the behavior of overflows and very appreciative of the help and support given by the Betic and Rifian Corridors prior to the their role in global ocean circulation. the Office National des Hydrocarbures et des Mines Messinian salinity crisis: A model study: Pale- In terms of consequences on Atlantic Ocean (ONHYM), Morocco. This project was funded by the , v. 30, p. 548–557, https://doi​ Industry Project supported by TOTAL, BP, ENI, circulation, a deeper input of MOW will reduce .org/10.1002/2014PA002719. ExxonMobil, Wintershal DEA, and TGS and was done Gladstone, R., Flecker, R., Valdes, P., Lunt, D., and the upper-ocean salinity in the Atlantic Ocean, in the framework of “The Drifters Research Group” Markwick, P., 2007, The Mediterranean hydro- while a shallower input will increase it. Saltier at Royal Holloway University of London (RHUL), logic budget from a late Miocene global climate near-surface Atlantic water is usually associated and it is related to projects CTM 2012–39599-C03, simulation: Palaeogeography, Palaeoclimatol- with stronger deep convection and overturning CGL2016–80445-R, and CTM2016–75129-C3–1-R. ogy, Palaeoecology, v. 251, p. 254–267, https:// (Rahmstorf, 2006; Kuhlbrodt et al., 2007). This doi​.org/10.1016/​j.palaeo.2007.03.050. GRID-Arendal (GRIDA), 2013, State the Mediter- impact, however, also depends on the ambient REFERENCES CITED Alhammoud, B., Meijer, P.T., and Dijkstra, H.A., ranean Marine and Coastal Environment: http:// stratification and mixing of the Atlantic Ocean, 2010, Sensitivity of Mediterranean thermohaline www.grida.no/resources/5885 (accessed Janu- which we cannot infer from these records. Fur- circulation to gateway depth: A model investiga- ary 2020). thermore, as these sedimentary records represent tion: Paleoceanography, v. 25, PA2220, https:// Hernández-Molina, F.J., et al., 2014, Contourite pro- doi​.org/10.1029/2009PA001823. cesses associated to the Mediterranean Outflow an early stage of paleo-MOW formation, it is Water after its exit from the Gibraltar Strait: Global unclear how much time it took to fully estab- Baringer, M.O.N., and Price, J.F., 1999, A review of the of the Mediterra- and conceptual implications: Geology, v. 42, lish the MOW in the Atlantic. Despite these nean outflow: , v. 155, p. 63–82, p. 227–230, https://doi​.org/10.1130/G35083.1. uncertainties, less input of salt and heat from https://doi.org/10.1016/S0025-3227(98)00141-8​ . Hernández-Molina, F.J., et al., 2016, Oceanographic the MOW would have weakened the Atlantic Capella, W., et al., 2017a, Sandy contourite drift in processes and morphosedimentary products along the Iberian margins: A new multidisciplinary Meridional Overturning Circulation, while the the late Miocene Rifian Corridor (Morocco): Reconstruction of depositional environments approach: Marine Geology, v. 378, p. 127–156, depth of the input would have impacted the con- in a foreland-basin seaway: Sedimentary Geol- https://doi​.org/10.1016/​j.margeo.2015.12.008. nection with surface-water properties, providing ogy, v. 355, p. 31–57, https://doi​.org/10.1016/​ Herrero, M.J., Marfil, R., Escavy, J.I., Al-Aasm, I., a less direct influence. j.sedgeo.2017.04.004. and Scherer, M., 2020, Diagenetic origin of Capella, W., Matenco, L., Dmitrieva, E., Roest, bipyramidal quartz and hydrothermal aragonites The intermittency of overflows resulting within the Upper Triassic saline succession of the from tectonic events and climatic variations W.M., Hessels, S., Hssain, M., Chakor-Alami, A., Sierro, F.J., and Krijgsman, W., 2017b, Thick- Iberian Basin: Implications for interpreting the at precessional to seasonal time scales is cur- skinned closing the Rifian Corridor: burial–thermal evolution of the basin: rently not considered in models because proper Tectonophysics, v. 710, p. 249–265, https://doi​ (Basel), v. 10, p. 177, https://doi​.org/10.3390/ sedimentary records are lacking. This record .org/10.1016/​j.tecto.2016.09.028. min10020177.

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Downloaded from http://pubs.geoscienceworld.org/gsa/geology/article-pdf/48/12/1194/5186221/1194.pdf by guest on 27 September 2021 Hüneke, H., and Stow, D.A.V., 2008, Identification of Longhitano, S.G., 2013, A facies-based depositional Schönfeld, J., and Zahn, R., 2000, Late glacial to ancient contourites: Problems and palaeoceano- model for ancient and modern, tectonically-con- Holocene history of the Mediterranean Outflow: graphic significance, in Rebesco, M., and Cam- fined tidal straits: Terra Nova, v. 25, p. 446–452, Evidence from benthic foraminiferal assemblages erlenghi, A., eds., Contourites: Elsevier Science https://doi​.org/10.1111/ter.12055. and stable isotopes at the Portuguese margin: Pal- Developments in 60, p. 323–344, Mutti, E., Cunha, R.S., Bulhoes, E.M., Arienti, L.M., aeogeography, Palaeoclimatology, Palaeoecol- https://doi.org/10.1016/S0070-4571(08)10017-6​ . and Viana, A.R., 2014, Contourites and turbi- ogy, v. 159, p. 85–111, https://doi​.org/10.1016/ Ivanovic, R.F., Valdes, P.J., Flecker, R., Gregoire, L.J., dites of the Brazilian marginal basins: American S0031-0182(00)00035-3. and Gutjahr, M., 2013, The parameterisation of Association of Petroleum Geologists Search and Seidenkrantz, M.S., Kouwenhoven, T.J., Jorissen, F.J., Mediterranean-Atlantic water exchange in the Discovery article 51069. Shackleton, N.J., and Van der Zwaan, G.J., 2000, Hadley Centre model HadCM3, and its effect on Rahmstorf, S., 2006, Thermohaline ocean circula- Benthic foraminifera as indicators of changing modelled North Atlantic climate: Ocean Mod- tion, in Elias, S.A., ed., Encyclopedia of Qua- Mediterranean-Atlantic water exchange in the late elling, v. 62, p. 11–16, https://doi​.org/10.1016/​ ternary Science: Amsterdam, Netherlands, Else- Miocene: Marine Geology, v. 163, p. 387–407, j.ocemod.2012.11.002. vier, p. 739–750. https://doi.org/10.1016/S0025-3227(99)00116-4​ . Knutz, P.C., 2008, Paleoceanographic signifi- Rebesco, M., Hernández-Molina, F.J., Van Sierro, F.J., et al., 1999, Messinian pre- cance of contourite drifts, in Rebesco, M., Rooij, D., and Wåhlin, A., 2014, Contou- sapropels and precession-induced oscillations in and Camerlenghi, A., eds., Contourites: Else- rites and associated sediments controlled western Mediterranean climate: Marine Geol- vier Science Developments in Sedimentology by deep-water circulation processes: State- ogy, v. 153, p. 137–146, https://doi.org/10.1016/​ 60, p. 511–535, https://doi.org/10.1016/S0070-​ of-the-art and future considerations: Marine S0025-3227(98)00085-1. 4571(08)10024-3. Geology, v. 352, p. 111–154, https://doi​ Stow, D., and Smillie, Z., 2020, Distinguishing between Kuhlbrodt, T., Griesel, A., Montoya, M., Lever- .org/10.1016/j.margeo​ .2014.03.011​ . deep-water sediment facies: Turbidites, contou- mann, A., Hofmann, M., and Rahmstorf, S., Rogerson, M., Rohling, E.J., Bigg, G.R., and Ramirez, rites and hemipelagites: Geosciences, v. 10, p. 68, 2007, On the driving processes of the Atlantic J., 2012, Paleoceanography of the Atlantic-Med- https://doi.org/10.3390/geosciences10020068​ . Meridional Overturning Circulation: Reviews iterranean exchange: Overview and first quanti- Stow, D.A., Hernández-Molina, F.J., Llave, E., Say- of Geophysics, v. 45, RG2001, https://doi​ tative assessment of climatic forcing: Reviews ago-Gil, M., Díaz del Río, V., and Branson, A., .org/10.1029/2004RG000166. of Geophysics, v. 50, RG2003, https://doi​ 2009, -velocity : The estimation Legg, S., et al., 2009, Improving oceanic overflow .org/10.1029/2011RG000376. of bottom current velocity from bedform obser- representation in climate models: The Gravity Roldán, F.J., et al., 2014, Basin evolution associ- vations: Geology, v. 37, p. 327–330, https://doi​ Current Entrainment Climate Process Team: ated to curved thrusts: The Prerif Ridges in the .org/10.1130/G25259A.1. Bulletin of the American Meteorological Volubilis area (Rif Cordillera, Morocco): Jour- Toucanne, S., Mulder, T., Schönfeld, J., Hanquiez, V., Society, v. 90, p. 657–670, https://doi​ nal of Geodynamics, v. 77, p. 56–69, https://doi​ Gonthier, E., Duprat, J., Cremer, M., and Zara- .org/10.1175/2008BAMS2667.1. .org/10.1016/​j.jog.2013.11.001. gosi, S., 2007, Contourites of the Gulf of Cadiz: A Llave, E., Schönfeld, J., Hernández-Molina, F.J., Mulder, Sani, F., Del Ventisette, C., Montanari, D., Bendkik, high-resolution record of the paleocirculation of T., Somoza, L., Del Río, V.D., and Sánchez-Almazo, A., and Chenakeb, M., 2007, Structural evolu- the Mediterranean Outflow Water during the last I., 2006, High-resolution of the Medi- tion of the Rides Prerifaines (Morocco): Struc- 50,000 years: Palaeogeography, Palaeoclimatol- terranean outflow contourite system in the Gulf of tural and seismic interpretation and analogue ogy, Palaeoecology, v. 246, p. 354–366, https:// Cadiz during the late Pleistocene: The impact of modelling experiments: International Journal doi​.org/10.1016/​j.palaeo.2006.10.007. Heinrich events: Marine Geology, v. 227, p. 241– of Earth Sciences, v. 96, p. 685–706, https://doi​ 262, https://doi.org/10.1016/​ j.margeo.2005.11.015​ . .org/10.1007/s00531-006-0118-2. Printed in USA

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