Research Group on Sedimentary Record of Climatic Changes– SERCC

[EN] SERCC was created at the end of 2021 in response to the recent incorporation of the IGME as a National Centre of the Spanish Research Council (CSIC) and the need to converge to CSIC´s research organization, which is structured on Research Groups as basic units. SERCC is composed of 11 persons (6 Staff Scientists – 3 of them recently promoted to Scientific Researchers, 4 Specialized Technicians and 1 Predoctoral Student), and focuses on the imprint of past climate changes on the characteristics and properties of the sedimentary record, accumulated both in marine and continental realms.Peer reviewe

Gibraltar Outflow and Mediterranean overturning circulation during the last 500 ky

20th Congress of the International Union for Quaternary Research (INQUA). Dublin, 25th and 31st July 2019, AbstractsIn order to explore past changes in the Mediterranean Outflow Water (MOW) we analyzed the fine sand content in the sediments together with some geochemical proxies and planktic and benthic stable isotopes at IODP site U1389. This site was recovered in the vicinity of the Strait of Gibraltar along the path of the main core of the MOW. The content of fine sand together with Zr/Al ratios were used to investigate the MOW speed variability along the past 500 ky. The MOW speed variability at this site was mainly driven by changes in the density contrast between the Inflow and Outflow, which was, in turn, governed by changes in the Mediterranean heat and freshwater budgets. Events of enhanced freshwater input to the Mediterranean associated to northward shifts of the Intertropical convergence Zone reduced the density contrast at Gibraltar and weakened the MOW at Gibraltar. Weak MOW events were recorded at times of sapropel deposition in the eastern Mediterranean. At millennial scale, the MOW intensified at times of Greenland stadials and weakened during interstadials. However, during Heinrich stadials typical three-phase events were observed, with a sandy contourite layer at the bottom and top and a phase of weak MOW in the middle of the stadial, coinciding with the arrival of icebergs to the Gulf of Cadiz. For Heinrich stadial 1 this weak MOW event occurred at the time of the massive release of icebergs from the Laurentian ice sheets. However, the inflow of less saline water to the Mediterranean should have increased not decreased the density contrast between the Inflow and Outflow, especially because freshwater discharge to the Mediterranean from the African monsoons was extremely low. We propose different scenarios to explain these weak MOW events in the middle of Heinrich stadials that were certainly triggered by prominent changes in the Mediterranean heat and freshwater budget.Universidad de Salamanca, EspañaUniversity of Cambridge, Reino UnidoLeibniz-Laboratory for Radiometric Dating and Isotope Research, AlemaniaJapan Agency for Marine-Earth Science and Technology, JapónInstitute of Earth Sciences, Heidelberg University, AlemaniaRoyal Holloway, University of London, Reino UnidoSchool of Environmental Sciences, University of Hull, Reino UnidoInstituto Geológico y Minero de España, Españ

Balance hídrico a través del Estrecho de Gibraltar (Golfo de Cádiz – Mar de Alborán) durante los últimos 18 Ka

Jornadas de Paleontología (33. 2017. Cádiz)El Golfo de Cádiz se comunica con el Mar Mediterráneo a través del Estrecho de Gibraltar, por lo que se considera un lugar clave para estudiar y comprender la dinámica de corrientes entre el Atlántico y el Mediterráneo. Con el objetivo de analizar los cambios ocurridos en el balance hídrico del Mediterráneo se ha llevado a cabo la caracterización isotópica de la masa de agua superficial atlántica mediante el análisis de la temperatura de la superficie del agua (SST=Sea Surface Temperature) a partir del porcentaje de las especies de foraminíferos planctónicos presentes en muestras pertenecientes al testigo U1389 situado en el Golfo de Cádiz.Instituto Geológico y Minero de España, EspañaDepartamento de Geología, Universidad de Salamanca, EspañaPeer reviewe

Tore Pool: a singular sediment trap for paleoproductivity in the North Atlantic gyre

International Conference on Paleoceanography (12º. 2016. Utrecht)The Tore pool is a 5.5 km conical deep basin within the Tore seamount, located 300 km off the Iberian margin in the North Atlantic at 40°N of latitude. The vacant Tore seamount acts as a natural, giant sediment trap, and anticipates a singular environment where many biogeochemical and physical processes converge into an isolated and confined space from the open deep ocean. Trapped vertical particle flux of surface productivity is deposited without sediment resuspension and erosion by bottom currents. The Tore pool has a restricted gate for exchange of Atlantic deep waters. This implies a potential better preservation of inside deep sea carbonates compared to the North Atlantic open ocean, protected from O-rich Antarctic Bottom Water (AABW) over glacial stages. Additionally, limited O into the pool would favour seldom anoxic conditions by consumption of organic matter. We base our study on the 25 m long Calypso Giant core MD13-3473 taken within the Tore pool, where geochemical and physical analyses are being performed. The sequence covers the last 400 thousand years (down to Marine Isotope Stage 11). Orbital as well as millennial scale climate changes are present in the records. In this case, an accurate stratigraphy is crucial, as it is the identification of occasional gravitational facies, and critical for the purpose of estimation of sedimentation rate and vertical fluxes. Estimation of marine biomass and productivity fluxes in areas of subtropical gyres, contributes to understand capacity of global marine sequestration of atmospheric gases at orbital scale.Instituto Geológico y Minero de España, EspañaLaboratorio Nacional de Energia e Geología, PortugalLaboratoire des Sciences du Climat et de l'Environnement, Centre National de la Recherche Scientifique, FranceLaboratoire des Sciences du Climat et de l'Environnement, Université Paris-Saclay, Franc

Investigating Miocene Mediterranean-Atlantic Gateway Exchange (IMMAGE) - an amphibious drilling proposal

European Geosciences Union General Assembly (2017. Viena)Today Mediterranean seawater flows out through the Gibraltar Straits, forming a saline plume at intermediate depths in the Atlantic. The plume’s sedimentary record of distinctive, contouritic deposits has recently been recovered during IODP Leg 339 in the Gulf of Cadiz documenting a Mediterranean contribution to Atlantic thermohaline circulation since the Pliocene. However, before the Pliocene, the conduit for Mediterranean-Atlantic exchange is unclear. Gibraltar may have already been open, but two additional marine corridors also existed through 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) and recovering a complete record of the MSC is the target of current IODP drilling proposals (e.g. DREAM). Understanding both the causes of high-amplitude salinity change in the Mediterranean and its global consequences for thermohaline circulation in the Atlantic is dependent on recovering a complete record of Mediterranean-Atlantic exchange before, during and after the MSC. This key objective of the IMMAGE drilling proposal requires core recovery on-shore at the mouths of the Betic and Rifian corridors which are now exposed on land, as well as offshore, in the Alborán Sea and on the Atlantic continental margin. Consequently to meet this objective, an amphibious drilling strategy is necessary, involving both IODP and ICDP targets. In addi tion to allowing us to reconstruct Mediterranean-Atlantic exchange during high amplitude salinity fluctuations and identify the conduit through which exchange occurred, the sediments recovered from IMMAGE drilling will also provide us with a unique and explicit test for ocean physics hypotheses describing the location, size and velocity of overflow plumes under conditions where the density contrast between the two water bodies is up to two orders of magnitude higher than today.School of Geographical Sciences, University of Bristol, Reino UnidoInstituto Geológico y Minero de España, Españ

Deglaciation and Holocene climate change in the Tore Seamount

Past Global Changes. Open Science Meeting (5º. 2017. Zaragoza)The Tore Seamount has a 5500 m water depth deep basin in the middle - isolated from the open ocean, and providing a singular palaeoclimatic record in the North Atlantic Ocean. It is located about 300 km west off the Iberian margin, and we predict acts as a giant sediment trap of subtropical gyre productivity. Core MD13-3473 was recovered using a Calypso giant piston corer during cruise Gateways Tore Eurofleets [MD194], in 2013, onboard the R/V Marion Dufresne. Although the 24 m long sediment record covers the last 430 thousand years (from Marine Isotopic Stage 11 (MIS 11) to the Holocene), this study focus on the last deglaciation period. To establish the best chronostratigraphy for this time interval (6 ky–21 ky BP.) and assess temperature and productivity changes in the Tore Seamount record, different analyses have been carried out at high-resolution: color intensities, physical properties, geochemical composition, organic carbon, microscopical and compositional analysis of lithic particles (ice-rafted debris) and planktonic foraminiferal assemblages. By combining these records, we were able to approach glacial to interglacial changes in temperature and productivity, and identify Heinrich event 1 (HE1), which altogether reveals specific lithological, biological, and physical characteristics. An age model has been developed for the deglaciation based on five AMS radiocarbon ages, and correlation with the GISP2 ice core and d18OG.bulloides curves from other nearby marine cores of the North Atlantic Ocean. Two AMS radiocarbon ages gave anomalous data, due to the presence of reworked material in these samples and pointing to a turbidite deposit in the middle of hemipelagic sediment, whose emplacement was just after HE1. A thorough study of all these data is necessary to prove the singularity and exceptional paleoceanographic capacity of the Tore Seamount as a sediment trap in the North Atlantic.Instituto Geológico y Minero de España, EspañaLaboratorio Nacional de Energia e Geología, PortugalPeer reviewe

Paleoceanographic and climatic implications of a new Mediterranean Outflow branch in the southern Gulf of Cadiz

The presence of contourite drifts in the southern Gulf of Cadiz (GoC) along the Moroccan margin raises questions about the (re)circulation of Mediterranean Outflow Water (MOW) in the GoC and the origin of the currents depositing them. Here, we compare two cores representative of Iberian and Moroccan contourite drifts, covering the last 22 kyr. Although the whole sequence is contouritic in character, it reflects the interaction of distinctive silty-contourite facies (high flow velocity periods) imbedded in muddy-contourite facies (low flow velocity periods). Evidence from benthic foraminifera d13C, sortable silt grain-size, oceanographic CTD profiles and numerical simulations, indicate the Mediterranean water mass as the source of the southern contourite deposits. Our data, therefore, suggests an additional branch of upper-MOW veering southwards off the Straits of Gibraltar along the Moroccan margin. During MIS-(Marine Isotope Stage) 2, upper-MOW was a sluggish current while in the Holocene upper-MOW dominated as a fast, semi-steady flow. Throughout the deglaciation, silty contourites associated with higher flow speeds were deposited in the northern and southern GoC during cold events such as Heinrich Stadial 1 (HS1) and the Younger Dryas, forced by global millennial-scale climate variability. Millennial variability also appears to drive the deposition of silty-contourites in the Holocene. We estimated an average duration of 1 ka for the process of depositing a fast contourite unit. The case of silty-contourite I6 (within HS1) allows us to illustrate with extremely high resolution a “rapid” sequential change in circulation, with gradual slow-down of dense Mediterranean water while surface was freshening (HS1), provoking injection of high-salinity intermediate waters (via contour-currents) into the GoC,and hence the North Atlantic. The subsequent brief collapse of dense water formation in the Mediterranean Sea triggered a major increase in sea surface temperatures (10 C/ka) in the GoC, developing into the next interstadial (Bølling/Allerød). The impact of Mediterranean intermediate waters is manifested here by triggering a substantial rearrangement of intermediate and deep circulation in the North Atlantic, which would have further impacted the Atlantic Meridional Overturning Circulation (AMOC).Instituto Geológico y Minero de España, EspañaUnidad de Tres Cantos, Instituto Geológico y Minero de España, EspañaNational Oceanography Centre, Reino Unid

The record of a high-energy event in a mud entrapment on the inner shelf off the Guadiana river

Reunião do Quaternário Ibérico (9º. 2017. Algarve)Recent environmental changes associated with high-energy events and human impacts were investigated in a mud entrapment confined in the paleo-Guadiana incised valley. Those changes were recorded in a gravity core during the last 2500 years. An erosional event seems to have occurred at ca. 500 cal yr BP but it is not clear how much sediment was removed. This event was followed by an increase in river discharges until ca. 465 cal yr BP while the benthic foraminiferal faunas were dominated by species associated with shallow-water sandy sediments. Upward, sedimentological and benthic foraminiferal variations indicated environmental changes, promoted by variable sediment supplies to the shelf.Centro de Investigação Marinha e Ambiental, Universidade do Algarve, PortugalInstituto Andaluz de Ciencias de la Tierra, Consejo Superior de Investigaciones Científicas, EspañaInstituto Andaluz de Ciencias de la Tierra, Universidad de Granada, EspañaGEOMAR Helmholtz Centre for Ocean Research Kiel, AlemaniaInstituto Geológico y Minero de España, EspañaSchool of Coastal and Marine Systems Sciences, Coastal Carolina University, Estados UnidosDepartment of Geosciences, University of Bremen, AlemaniaPeer reviewe

Zooming into the Mediterranean outflow fossil moat during the 1.2–1.8 million years period (Early-Pleistocene): an approach by radiogenic and stable isotopes

The fossil Alvarez Cabral erosive Moat contains hemipelagite, contourite and turbidite facies where oceanography changes in the Mediterranean outflow are archived over the 1.2-1.8 Myr time period. Here we used Pb and Sr radiogenic isotopes to trace water masses and sediment source changes, for the first time in twenty glacial-interglacial (G-I) cycles of the Early-Pleistocene interval, and the last Glacial Maximum through Holocene cycle (including the Younger Dryas and Heinrich Stadial-1). A mixing line of Pb isotopes gives reliable low radiogenic 208Pb/204Pb, 206Pb/204Pb, and 206Pb/207Pb typical of Mediterranean Outflow Water (MOW) in one end-member and the signature of high radiogenic isotopes of Atlantic Waters (AW) towards the second endmember. The 87Sr/86Sr isotopes also display two end-members of the mixing line between eolian transport/dust source (0.71) and fluvial transport/weathering source (0.73) previously proposed in the Gulf of Cadiz. Combination of Pb and Sr radiogenic isotopes with O and C stable isotopes of planktonic and benthic foraminifera, and the response of foraminifera benthos over the Early-Pleistocene interval, reveals a direct link between water masses circulation and shifts in G-I. We found a persistent cyclic pattern of MOW circulation and fluvial deposition during glaciations and AW and aeolian influence during interglaciations. On site U1386B/C, the upper-MOW was less ventilated but productive and with high flux of organic flux matter during glacials, while Atlantic Waters were better ventilated, enriched in O, but less productive during interglacials. We infer that shifts in ocean and atmospheric processes in the Gulf of Cadiz were strongly controlled by Earth´s obliquity (41kyrcycle) and 35ºNH insolation during the Early-Pleistocene. We propose a correlation in changes in phase-relationship between precession and obliquity.Instituto Geológico y Minero de España, EspañaSede de Tres Cantos, Instituto Geológico y Minero de España, EspañaCentro de Investigaciones Energéticas, Medioambientales y Tecnológicas, Españ