Divergent Mediterranean seawater circulation during Holocene sapropel formation – Reconstructed using Nd isotopes in fish debris and foraminifera

Wu, Jiawang; Pahnke, Katharina; Böning, Philipp; Wu, Li; Michard, A.; Lange, G. J. de

doi:10.1016/j.epsl.2019.01.036

Cited by 24 publications

(46 citation statements)

References 64 publications

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“…Further investigations will be necessary to understand such large range of εNd variations obtained on core MD04-2797CQ. Nevertheless, core MD04-2797CQ presents similar long term variations of εNd values to those obtained from records in the eastern Levantine Basin, such as cores BC19, SL114, MD90-964, and MS27PT (Figures 7D and 7E) (Cornuault et al, 2018;Duhamel et al, 2020;Wu et al, 2019). All of these cores, collected in the upper EMDW/lower LIW, indicate more radiogenic values between 14 and 6 cal kyr BP, reaching up to −2.1 ± 0.2 for core MS27PT and −3.2 ± 0.2 for core MD90-964.…”

Section: Comparison Of the Liw εNd Between The Levantine Basin And The Tyrrhenian Seasupporting

confidence: 73%

“…Such peak of radiogenic values is coleval to those observed in core MD01-2472 during warm substages of the MIS 5 and the MIS1. Such radiogenic εNd values have also been observed during the African humid periods in the early Holocene and during the Eemian in several other EMDW records (Duhamel et al, 2020;Osborne et al, 2010;Scrivner et al, 2004;Wu et al, 2019). EMDW εNd maxima during interglacial stages are quite similar, with more radiogenic εNd values centered at 121, 101, 80, and 9 cal kyr BP in core MD01-2472 (Figure 6d), which correspond to the timing of long-term African monsoon oscillations controlled by precession-driven insolation changes.…”

Section: Long-term Hydrological Variability During the Last Glacial-interglacial Cyclesupporting

confidence: 71%

“…However, we cannot entirely exclude the possibility that a marked reduction in eo-COLIN ET AL. Jiménez-Espejo et al, 2015) and the EMS (Cornuault et al, 2018;Wu et al, 2019) have indicated that glacial periods are not systematically associated with εNd values more unradiogenic than those of interglacial times (Figures 5b and 6) (Duhamel et al, 2020).…”

Section: Significance Of Past εNd Variations Obtained On Foraminifera Of Sediments From the Central Mediterranean Seamentioning

confidence: 92%

“…the EMS (Duhamel et al, 2020;Wu et al, 2019), and notably in the Levantine Sea at greater depth, displays higher εNd during S1a and even beforehand (14 cal kyr BP in the Levantine Basin) (Figures 7d and 7e). These εNd records also display a significant decrease during the time interval of S1 deposition (Figures 7d and 7e), whereas in the Central Mediterranean Sea, εNd is similarly high during S1a and S1b (Corsica Trough and South of Sardinia).…”

Section: Comparison Of the Liw εNd Between The Levantine Basin And The Tyrrhenian Seamentioning

confidence: 97%

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Changes in the Intermediate Water Masses of the Mediterranean Sea During the Last Climatic Cycle—New Constraints From Neodymium Isotopes in Foraminifera

Colin

Duhamel

Siani

et al. 2021

Paleoceanog and Paleoclimatol

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The Mediterranean Sea is a semi-enclosed basin characterized by arid conditions and connected to the North Atlantic through the Strait of Gibraltar (sill depth of ∼300 m). This generates a Mediterranean thermohaline circulation where the inflow of relatively fresh and cold surface Atlantic water (AW) is transformed into intermediate and deep waters in the Gulf of Lions, the Adriatic Sea, the Levantine Basin and the Aegean Sea (Robinson et al., 2001;Schroeder et al., 2012). In particular, the Levantine Intermediate Water (LIW) is formed in the Cyprus-Rhodes area from where it spreads westwards into the entire Mediterranean Sea at water depths of between ∼150 and 700 m (Lascaratos et al., 1993;Malanotte-Rizzoli et al., 1999). This overturning circulation is associated with an outflow of saltier and warmer intermediate water into the North Atlantic corresponding to the Mediterranean Outflow Water (MOW) (Robinson et al., 2001;Schroeder et al., 2012). Because the MOW contains up to ∼80% of LIW, the water mass formation in the Levantine Sea plays an important role for the salty outflow to the North Atlantic through the Strait of Gibraltar. A link between the intensification of the MOW and the intensity of the Atlantic Meridional Overturning Circulation (AMOC) has been proposed (

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Section: Comparison Of the Liw εNd Between The Levantine Basin And The Tyrrhenian Seasupporting

confidence: 73%

Section: Long-term Hydrological Variability During the Last Glacial-interglacial Cyclesupporting

confidence: 71%

Section: Significance Of Past εNd Variations Obtained On Foraminifera Of Sediments From the Central Mediterranean Seamentioning

confidence: 92%

Section: Comparison Of the Liw εNd Between The Levantine Basin And The Tyrrhenian Seamentioning

confidence: 97%

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Changes in the Intermediate Water Masses of the Mediterranean Sea During the Last Climatic Cycle—New Constraints From Neodymium Isotopes in Foraminifera

Colin

Duhamel

Siani

et al. 2021

Paleoceanog and Paleoclimatol

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“…At a water depth of 552 m, our studied core is, today, mainly located at the transition between LIW and the Eastern Mediterranean Deep Water (Mojtahid et al, 2019). However, it may have been bathed by different water masses during the LGM that is characterized by a lower sea level or during the S1 period characterized by a reduced LIW formation (Cornuault et al, 2018;Freydier et al, 2001;Scrivner et al, 2004;Tachikawa et al, 2015;Wu et al, 2019).…”

Section: Oceanographic Settingmentioning

confidence: 99%

Suborbital Hydrological Variability Inferred From Coupled Benthic and Planktic Foraminiferal‐Based Proxies in the Southeastern Mediterranean During the Last 19 ka

Houedec

Mojtahid

Bicchi

et al. 2020

Paleoceanog and Paleoclimatol

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We present a high‐resolution study covering the past 19 ka from the southeastern Mediterranean Sea, based on benthic foraminiferal faunas and their stable oxygen and carbon isotopes. These data are integrated with previously published and newly acquired planktic foraminiferal data from the same sediment core in order to investigate the benthic‐planktic coupling and its response to past suborbital climate variability. On a millennial timescale, foraminiferal communities and their isotopic signatures vary following three main time periods (late glacial, sapropel S1 [~10.1–6.5 ka], and mid‐Holocene to Late Holocene). Within these intervals, we identified short‐timescale changes related to the carbon export and hydrological conditions. During the deglaciation, and except for the Younger Dryas, the coupled benthic‐planktic data indicate an overall poorly mixed water column with a low productivity. During S1 event, our data confirm the presence of a highly stratified water column, with enhanced primary productivity export to the deep sea, being associated to high Nile River activity. While the foraminiferal ecosystem is strongly driven by the combined influence of overturning circulation and the Nile River activity until the end of the African humid period, we suggest a more regional eastern Mediterranean climatic‐driven response of the foraminiferal community over the mid‐Holocene to Late Holocene. A strong multicentennial variability, probably associated to solar forcing, was found for both benthic and planktic records, and a supplementary 1,600‐year mode was found for the benthic data, suggesting a potential overturning circulation‐driven forcing for the latter.

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Tracing water column euxinia in Eastern Mediterranean Sapropels S5 and S7

et al. 2020

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Sapropels S5 and S7 formed in the semi-enclosed Eastern Mediterranean Sea (EMS) during peak interglacial periods MIS5e and MIS7a, respectively, are considered among the most strongly developed Quaternary sapropels. This study investigates the redox dynamics of the water column during their formation, via Fe isotope and Fe speciation studies of cores taken at 2550 m depth at site ODP-967. Both sapropels show an inverse correlation between d 56 Fe and Fe T /Al, with slopes mostly matching that found for the Black Sea, pointing to a benthic shelf to basin shuttle of Fe and subsequent precipitation of Fe sulphides in euxinic bottom waters. An exception to these Black Sea-type trends occurs during the later, peak, stages of S7, where the negative d 56 Fe -Fe T /Al slope shallows. Fe speciation studies reveal that the dominant highly reactive Fe phase (Fe HR ) in the sapropels is pyrite, with Fe (oxyhydr)oxides forming the second major mineral component. Correspondingly, Fe HR /Fe T plots show increased strengthening of anoxic water conditions during the passage from presapropel sediment into the sapropel. Nevertheless, despite the evidence for euxinic conditions from both Fe isotopes and high Mo concentrations in the sapropel, Fe py /Fe HR ratios remain below values commonly used to identify water column euxinia. This apparent contradiction is ascribed to the sedimentary preservation of a high flux of crystalline Fe (oxyhydr)oxide minerals to the basin, which resulted in a relatively low degree of sulphidation, despite the presence of euxinic bottom waters.Thus, the operationally defined ferruginous/euxinic boundary for EMS sapropels is better placed at Fe py /Fe HR = 0.6, which is somewhat below the usually ascribed lower limit of 0.7. Consistent with the significant presence of crystalline Fe (oxyhydr)oxides, the change in the d 56 Fe -Fe T /Al slope during peak S7 is ascribed to an enhanced monsoon-driven flux of detrital Fe(III) oxides from the River Nile into the EMS basin and comcomitant diagenetic sulphidation. Euxinic water column conditions in sapropel S5 and S7 are interpreted here to reflect the positive balance between dissolved sulphide formation and rates of reductive dissolution of Fe (oxyhydr)oxide minerals. Both of these parameters in turn depend on the extent to which water overturn times are reduced and export productivity increased during sapropel formation.

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Divergent Mediterranean seawater circulation during Holocene sapropel formation – Reconstructed using Nd isotopes in fish debris and foraminifera

Cited by 24 publications

References 64 publications

Changes in the Intermediate Water Masses of the Mediterranean Sea During the Last Climatic Cycle—New Constraints From Neodymium Isotopes in Foraminifera

Changes in the Intermediate Water Masses of the Mediterranean Sea During the Last Climatic Cycle—New Constraints From Neodymium Isotopes in Foraminifera

Suborbital Hydrological Variability Inferred From Coupled Benthic and Planktic Foraminiferal‐Based Proxies in the Southeastern Mediterranean During the Last 19 ka

Tracing water column euxinia in Eastern Mediterranean Sapropels S5 and S7

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