20,000 years of Nile River dynamics and environmental changes in the Nile catchment area as inferred from Nile upper continental slope sediments

Revel, Marie; Ducassou, Emmanuelle; Skonieczny, Charlotte; Colin, Christophe; Bastian, Luc; Bosch, Delphine; Migeon, Sébastien; Mascle, J.

doi:10.1016/j.quascirev.2015.10.030

Cited by 100 publications

(106 citation statements)

References 109 publications

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“…2a). From the late glacial to the Holocene, SST variations show a similar pattern to that previously observed in the Gulf of Lions and Tyrrhenian Sea (Kallel et al, 1997;Melki et al, 2009) as well as in the Alboran Sea (Martrat et al, 2014;Rodrigo-Gámiz et al, 2014). They are globally synchronous for the main climatic transitions to the well-dated south Adriatic Sea core MD90-917 (Siani et al, 2004) confirming the robustness of the SU92-33 age model (Fig.…”

Section: Core Su92-33supporting

confidence: 84%

“…3a), also identified for various sites in the Mediterranean Sea Martrat et al, 2004Martrat et al, , 2014Essallami et al, 2007;Rodrigo-Gámiz et al, 2014). The B-A interval is associated with the so-called meltwater pulse 1A (e.g., Weaver et al, 2003) occurring at around 14.5 cal ka BP.…”

Section: Hydrological Changes In the Alboran And Balearic Seas Since mentioning

confidence: 89%

“…Differently from the CWC, the εNd composition of fossil planktonic foraminifera is not related to the ambient seawater at calcification depth but reflects the bottom and/or pore water εNd due to the presence of authigenic Fe-Mn coatings precipitated on their carbonate shell after deposition onto the sediment (Roberts et al, 2010;Elmore et al, 2011;Piotrowski et al, 2012;Tachikawa et al, 2014;Wu et al, 2015). Therefore, the εNd composition of planktonic foraminiferal tests can be used as a useful tracer of deep-water circulation changes in the past, although the effect of pore water on foraminiferal εNd values could potentially complicate the interpretation (Tachikawa et al, 2014).…”

Section: Introductionmentioning

confidence: 93%

“…Each sample was rinsed thoroughly with Milli-Q water until the solution was clear and free of clay. The cleaned samples were dissolved in 1N acetic acid and finally centrifuged to ensure that all residual particles were removed, following the procedure described in Roberts et al (2010). Nd was separated following the analytical procedure reported in Wu et al (2015).…”

Section: Nd Isotope Measurements On Planktonic Foraminiferamentioning

confidence: 99%

“…1). As the Heinrich events over the last glacial period are characterized by colder and fresher surface water in the Alboran Sea Pérez-Folgado et al, 2003;Martrat et al, 2004Martrat et al, , 2014Rodrigo-Gámiz et al, 2014) and dry climate on land over the western Mediterranean Sea (Allen et al, 1999 Sanchez Goni et al, 2002;Bartov et al, 2003), lighter δ 18 O values of planktonic G. bulloides are thought to be the result of the inflow of freshwater derived from the melting of icebergs in the Atlantic Ocean into the Mediterranean Sea Rogerson et al, 2008). During this time interval, the δ 13 C record of C. pachyderma from the Balearic Sea (core SU92-33) displays a decreasing δ 13 C trend after ∼ 16 cal ka BP (from 1.4 to 0.9 ‰; Table 4; Fig.…”

Section: Hydrological Changes In the Alboran And Balearic Seas Since mentioning

confidence: 99%

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Hydrological variations of the intermediate water masses of the western Mediterranean Sea during the past 20 ka inferred from neodymium isotopic composition in foraminifera and cold-water corals

et al. 2017

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Abstract. We present the neodymium isotopic composition (εNd) of mixed planktonic foraminifera species from a sediment core collected at 622 m water depth in the Balearic Sea, as well as εNd of scleractinian cold-water corals (CWC; Madrepora oculata, Lophelia pertusa) retrieved between 280 and 442 m water depth in the Alboran Sea and at 414 m depth in the southern Sardinian continental margin. The aim is to constrain hydrological variations at intermediate depths in the western Mediterranean Sea during the last 20 kyr. Planktonic (Globigerina bulloides) and benthic (Cibicidoides pachyderma) foraminifera from the Balearic Sea were also analyzed for stable oxygen (δ 18 O) and carbon (δ 13 C) isotopes. The foraminiferal and coral εNd values from the Balearic and Alboran seas are comparable over the last ∼ 13 kyr, with mean values of −8.94 ± 0.26 (1σ ; n = 24) and −8.91 ± 0.18 (1σ ; n = 25), respectively. Before 13 ka BP, the foraminiferal εNd values are slightly lower (−9.28 ± 0.15) and tend to reflect higher mixing between intermediate and deep waters, which are characterized by more unradiogenic εNd values. The slight εNd increase after 13 ka BP is associated with a decoupling in the benthic foraminiferal δ 13 C composition between intermediate and deeper depths, which started at ∼ 16 ka BP. This suggests an earlier stratification of the water masses and a subsequent reduced contribution of unradiogenic εNd from deep waters. The CWC from the Sardinia Channel show a much larger scatter of εNd values, from −8.66 ± 0.30 to −5.99 ± 0.50, and a lower average (−7.31 ± 0.73; n = 19) compared to the CWC and foraminifera from the Alboran and Balearic seas, indicative of intermediate waters sourced from the Levantine basin. At the time of sapropel S1 deposition (10.2 to 6.4 ka), the εNd values of the Sardinian CWC become more unradiogenic (−8.38 ± 0.47; n = 3 at ∼ 8.7 ka BP), suggesting a significant contribution of intermediate waters originated from the western basin. We propose that western Mediterranean intermediate waters replaced the Levantine Intermediate WaPublished by Copernicus Publications on behalf of the European Geosciences Union. ter (LIW), and thus there was a strong reduction of the LIW during the mid-sapropel (∼ 8.7 ka BP). This observation supports a notable change of Mediterranean circulation pattern centered on sapropel S1 that needs further investigation to be confirmed.

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Section: Core Su92-33supporting

confidence: 84%

Section: Hydrological Changes In the Alboran And Balearic Seas Since mentioning

confidence: 89%

Section: Introductionmentioning

confidence: 93%

Section: Nd Isotope Measurements On Planktonic Foraminiferamentioning

confidence: 99%

Section: Hydrological Changes In the Alboran And Balearic Seas Since mentioning

confidence: 99%

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Hydrological variations of the intermediate water masses of the western Mediterranean Sea during the past 20 ka inferred from neodymium isotopic composition in foraminifera and cold-water corals

et al. 2017

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Circulation Changes in the Eastern Mediterranean Sea Over the Past 23,000 Years Inferred From Authigenic Nd Isotopic Ratios

Cornuault

Tachikawa

Vidal

et al. 2018

Paleoceanog and Paleoclimatol

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The Eastern Mediterranean Sea (EMS) is a key region to study circulation change because of its own thermohaline circulation. In this study, we focused on intermediate/deep water circulation since the Last Glacial Maximum (LGM) including the sapropel S1 period. Two cores from the Levantine Sea and the Strait of Sicily, respectively, collected at 1,780 m and 771 m water depth, were studied using 143Nd/144Nd (εNd) of foraminiferal tests and leachates as well as benthic foraminiferal stable isotopes (δ13C, δ18O). This approach allowed the determination of variations in (1) the North Atlantic water contribution to the Mediterranean basin, (2) water exchanges at the Strait of Sicily, and (3) the influence of the Nile River over the last 23,000 years. During the LGM, high benthic foraminiferal δ13C values indicate well‐ventilated intermediate and deep waters in the EMS. The εNd values were more radiogenic than at present, reflecting a smaller contribution of unradiogenic North Atlantic waters to the EMS due to reduced exchange at the Strait of Sicily. The sluggish circulation in the EMS initiated during deglaciation was further enhanced by increased Nile River freshwater inputs between 15 ka BP and the S1 period. Partial dissolution of Nile River particles contributed to an increase in EMS εNd. The large εNd gradient between the EMS and the Western Mediterranean Sea observed during LGM and S1 suggests that each basin had a distinct circulation mode. Decreasing εNd values at the Strait of Sicily after S1 reflected improved water exchange between both basins, leading to the modern circulation pattern.

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Warming and Cooling: The Medieval Climate Anomaly in Africa and Arabia

Lüning¹,

Gałka

Vahrenholt

2017

Paleoceanography

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The Medieval Climate Anomaly (MCA) is a well‐recognized climate perturbation in many parts of the world, with a core period of 1000–1200 Common Era. Here we present a palaeotemperature synthesis for the MCA in Africa and Arabia, based on 44 published localities. The data sets have been thoroughly correlated and the MCA trends palaeoclimatologically mapped. The vast majority of available Afro‐Arabian onshore sites suggest a warm MCA, with the exception of the southern Levant where the MCA appears to have been cold. MCA cooling has also been documented in many segments of the circum‐Africa‐Arabian upwelling systems, as a result of changes in the wind systems which were leading to an intensification of cold water upwelling. Offshore cores from outside upwelling systems mostly show warm MCA conditions. The most likely key drivers of the observed medieval climate change are solar forcing and ocean cycles. Conspicuous cold spikes during the earliest and latest MCA may help to discriminate between solar (Oort Minimum) and ocean cycle (Atlantic Multidecadal Oscillation, AMO) influence. Compared to its large share of nearly one quarter of the world's landmass, data from Africa and Arabia are significantly underrepresented in global temperature reconstructions of the past 2,000 years. Onshore data are still absent for most regions in Africa and Arabia, except for regional data clusters in Morocco, South Africa, the East African Rift, and the Levant coast. In order to reconstruct land palaeotemperatures more robustly over Africa and Arabia, a systematic research program is needed.

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20,000 years of Nile River dynamics and environmental changes in the Nile catchment area as inferred from Nile upper continental slope sediments

Cited by 100 publications

References 109 publications

Hydrological variations of the intermediate water masses of the western Mediterranean Sea during the past 20 ka inferred from neodymium isotopic composition in foraminifera and cold-water corals

Hydrological variations of the intermediate water masses of the western Mediterranean Sea during the past 20 ka inferred from neodymium isotopic composition in foraminifera and cold-water corals

Circulation Changes in the Eastern Mediterranean Sea Over the Past 23,000 Years Inferred From Authigenic Nd Isotopic Ratios

Warming and Cooling: The Medieval Climate Anomaly in Africa and Arabia

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20,000 years of Nile River dynamics and environmental changes in the Nile catchment area as inferred from Nile upper continental slope sediments

Cited by 100 publications

References 109 publications

Hydrological variations of the intermediate water masses of the western Mediterranean Sea during the past 20 ka inferred from neodymium isotopic composition in foraminifera and cold-water corals

Hydrological variations of the intermediate water masses of the western Mediterranean Sea during the past 20 ka inferred from neodymium isotopic composition in foraminifera and cold-water corals

Circulation Changes in the Eastern Mediterranean Sea Over the Past 23,000 Years Inferred From Authigenic Nd Isotopic Ratios

Warming and Cooling: The Medieval Climate Anomaly in Africa and Arabia

Contact Info

Product

Resources

About

Hydrological variations of the intermediate water masses of the western Mediterranean Sea during the past 20 ka inferred from neodymium isotopic composition in foraminifera and cold-water corals

Hydrological variations of the intermediate water masses of the western Mediterranean Sea during the past 20 ka inferred from neodymium isotopic composition in foraminifera and cold-water corals