High-resolution stratigraphic framework for Mediterranean sapropel S5: defining temporal relationships between records of Eemian climate variability

Cane, Tim; Rohling, Eelco J.; Kemp, Alan E. S.; Cooke, Steven J.; Pearce, Richard

doi:10.1016/s0031-0182(01)00461-8

Cited by 41 publications

(47 citation statements)

References 18 publications

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“…All S5 intervals were aligned on a common depth scale, based on Cane et al's () stratigraphic correlation framework for the same cores. Cane et al () placed KS205 on an ODP 971A‐equivalent depth using distinct events in planktic foraminiferal abundance and isotope observations as correlation markers and then fitting both linear and polynomial fits through the markers. The polynomial fit was then used to map the core onto the ODP 971A depth scale.…”

Section: Methodsmentioning

confidence: 99%

“…However, an age model has been developed for core LC21 using correlation of LC21 G. ruber δ 18 O to the U‐Th dated Soreq Cave speleothem δ 18 O record (Bar‐Matthews et al, ; Grant et al, ). Using the stratigraphic correlation between cores ODP 971A and LC21 (Cane et al, ; Marino et al, ), the ODP 971A depth scale can be transferred to the LC21 age model.…”

Section: Methodsmentioning

confidence: 99%

“…The LC21 data set includes previously published G. ruber (w) and N. pachyderma (d) data (Grant et al, ; Marino et al, , ). In addition, previously published data for core ODP 971 for G. ruber (w), N. pachyderma (d), and G. scitula over S5 (Cane et al, ; Rohling et al, ) have been included here to extend the comparison to a fourth site in the basin (Figure ).…”

Section: Approachmentioning

confidence: 99%

“…Visible extent of the S5 sapropel layer (gray shaded bands). Previously published data are used for KS205 and ODP 971 (Cane et al, ; Rohling et al, ) and LC21 G. ruber (w) and N. pachyderma (d; Marino et al, , ; Grant et al, ).…”

Section: Approachmentioning

confidence: 99%

“…The study interval for all diagnostics includes times before and after sapropel S5, when there is no evidence of excess freshwater input from an enhanced African monsoon. In addition, there is an interruption interval within S5, where excess freshwater influx is thought to have diminished, if not completely ceased (Cane et al, ; Rohling et al, , ; Scrivner et al, ). To model both sapropel‐forming conditions and normal conditions, different stages were defined within the study interval (Table ).…”

Section: Box Model Diagnostic Experimentsmentioning

confidence: 99%

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Quantification of African Monsoon Runoff During Last Interglacial Sapropel S5

Amies

Rohling

Grant

et al. 2019

Paleoceanog and Paleoclimatol

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Organic‐rich sapropel layers punctuate the eastern Mediterranean sedimentary sequence, recording deep‐sea anoxic events. The timing of sapropel deposition coincides with precession minima, which are associated with the northward migration of the monsoon rain belt over North Africa. The resultant increase in monsoon precipitation over the Sahara caused an increase in low‐δ18O freshwater runoff into eastern Mediterranean surface waters, which is reflected by negative δ18O anomalies in the records of planktic foraminiferal calcite. However, despite extensive research on sapropels, the magnitude of monsoon intensification and freshwater runoff, along with its influence on δ18O, remains elusive. Here, we present a quantification of African monsoon freshwater runoff into the eastern Mediterranean for the period of deposition of last interglacial sapropel S5 (~128.3–121.5 ka). Our method uses a box model of the Mediterranean Sea, which represents different water masses, and has been calibrated using δ18O from planktic foraminiferal species of different depth and seasonal habitats. The model was constrained with existing records of sea level and sea surface temperature then inverted to deconvolve the δ18O signal of the surface‐dwelling foraminiferal species Globigerinoides ruber (w) and calculate the freshwater runoff volume. Our calculated African monsoon runoff suggests large increases in freshwater discharge to the eastern Mediterranean (up to ~8.8 times the modern pre‐Aswan Nile discharge). Rapid onset of S5 deposition following the estimated increase in runoff strongly suggests a preconditioning of the eastern Mediterranean for sapropel deposition. Our study also provides insight into the stratification and warming of eastern Mediterranean surface waters during the S5 interval.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Approachmentioning

confidence: 99%

Section: Approachmentioning

confidence: 99%

Section: Box Model Diagnostic Experimentsmentioning

confidence: 99%

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Quantification of African Monsoon Runoff During Last Interglacial Sapropel S5

Amies

Rohling

Grant

et al. 2019

Paleoceanog and Paleoclimatol

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Calcareous nannofossil and planktonic foraminiferal distributional patterns during deposition of sapropels S6, S5 and S1 in the Libyan Sea (Eastern Mediterranean)

et al. 2009

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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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High-resolution stratigraphic framework for Mediterranean sapropel S5: defining temporal relationships between records of Eemian climate variability

Cited by 41 publications

References 18 publications

Quantification of African Monsoon Runoff During Last Interglacial Sapropel S5

Quantification of African Monsoon Runoff During Last Interglacial Sapropel S5

Calcareous nannofossil and planktonic foraminiferal distributional patterns during deposition of sapropels S6, S5 and S1 in the Libyan Sea (Eastern Mediterranean)

Tracing water column euxinia in Eastern Mediterranean Sapropels S5 and S7

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