The timing of Mediterranean sapropel deposition relative to insolation, sea-level and African monsoon changes

The Mediterranean basin is sensitive to global sea-level changes and African monsoon variability on orbital timescales. Both of these processes are thought to be important to the deposition of organic-rich sediment layers or ‘sapropels’ throughout the eastern Mediterranean, yet their relative influe...

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Published in:Quaternary Science Reviews
Main Authors: Grant, K.M., Grimm, R., Mikolajewicz, U., Marino, G., Ziegler, M., Rohling, E.J.
Format: Article in Journal/Newspaper
Language:English
Published: 2016
Subjects:
Online Access:https://eprints.soton.ac.uk/394375/
https://eprints.soton.ac.uk/394375/1/Grant%2520et%2520al%25202016_JQSR-D-15-00402R1.pdf
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spelling ftsouthampton:oai:eprints.soton.ac.uk:394375 2023-07-30T04:05:36+02:00 The timing of Mediterranean sapropel deposition relative to insolation, sea-level and African monsoon changes Grant, K.M. Grimm, R. Mikolajewicz, U. Marino, G. Ziegler, M. Rohling, E.J. 2016-05-15 text https://eprints.soton.ac.uk/394375/ https://eprints.soton.ac.uk/394375/1/Grant%2520et%2520al%25202016_JQSR-D-15-00402R1.pdf en English eng https://eprints.soton.ac.uk/394375/1/Grant%2520et%2520al%25202016_JQSR-D-15-00402R1.pdf Grant, K.M., Grimm, R., Mikolajewicz, U., Marino, G., Ziegler, M. and Rohling, E.J. (2016) The timing of Mediterranean sapropel deposition relative to insolation, sea-level and African monsoon changes. Quaternary Science Reviews, 140, 125-141. (doi:10.1016/j.quascirev.2016.03.026 <http://dx.doi.org/10.1016/j.quascirev.2016.03.026>). Article PeerReviewed 2016 ftsouthampton https://doi.org/10.1016/j.quascirev.2016.03.026 2023-07-09T22:07:38Z The Mediterranean basin is sensitive to global sea-level changes and African monsoon variability on orbital timescales. Both of these processes are thought to be important to the deposition of organic-rich sediment layers or ‘sapropels’ throughout the eastern Mediterranean, yet their relative influences remain ambiguous. A related issue is that an assumed 3-kyr lag between boreal insolation maxima and sapropel mid-points remains to be tested. Here we present new geochemical and ice-volume-corrected planktonic foraminiferal stable isotope records for sapropels S1 (Holocene), S3, S4, and S5 (Marine Isotope Stage 5) in core LC21 from the southern Aegean Sea. The records have a radiometrically constrained chronology that has already been synchronised with the Red Sea relative sea-level record, and this allows detailed examination of the timing of sapropel deposition relative to insolation, sea-level, and African monsoon changes. We find that sapropel onset was near-synchronous with monsoon run-off into the eastern Mediterranean, but that insolation–sapropel/monsoon phasings were not systematic through the last glacial cycle. These latter phasings instead appear to relate to sea-level changes. We propose that persistent meltwater discharges into the North Atlantic (e.g., at glacial terminations) modified the timing of sapropel deposition by delaying the timing of peak African monsoon run-off. These observations may reconcile apparent model–data offsets with respect to the orbital pacing of the African monsoon. Our observations also imply that the previous assumption of a systematic 3-kyr lag between insolation maxima and sapropel midpoints may lead to overestimated insolation–sapropel phasings. Finally, we surmise that both sea-level rise and monsoon run-off contributed to surface-water buoyancy changes at times of sapropel deposition, and their relative influences differed per sapropel case, depending on their magnitudes. Sea-level rise was clearly important for sapropel S1, whereas monsoon forcing was more ... Article in Journal/Newspaper North Atlantic University of Southampton: e-Prints Soton Quaternary Science Reviews 140 125 141
institution Open Polar
collection University of Southampton: e-Prints Soton
op_collection_id ftsouthampton
language English
description The Mediterranean basin is sensitive to global sea-level changes and African monsoon variability on orbital timescales. Both of these processes are thought to be important to the deposition of organic-rich sediment layers or ‘sapropels’ throughout the eastern Mediterranean, yet their relative influences remain ambiguous. A related issue is that an assumed 3-kyr lag between boreal insolation maxima and sapropel mid-points remains to be tested. Here we present new geochemical and ice-volume-corrected planktonic foraminiferal stable isotope records for sapropels S1 (Holocene), S3, S4, and S5 (Marine Isotope Stage 5) in core LC21 from the southern Aegean Sea. The records have a radiometrically constrained chronology that has already been synchronised with the Red Sea relative sea-level record, and this allows detailed examination of the timing of sapropel deposition relative to insolation, sea-level, and African monsoon changes. We find that sapropel onset was near-synchronous with monsoon run-off into the eastern Mediterranean, but that insolation–sapropel/monsoon phasings were not systematic through the last glacial cycle. These latter phasings instead appear to relate to sea-level changes. We propose that persistent meltwater discharges into the North Atlantic (e.g., at glacial terminations) modified the timing of sapropel deposition by delaying the timing of peak African monsoon run-off. These observations may reconcile apparent model–data offsets with respect to the orbital pacing of the African monsoon. Our observations also imply that the previous assumption of a systematic 3-kyr lag between insolation maxima and sapropel midpoints may lead to overestimated insolation–sapropel phasings. Finally, we surmise that both sea-level rise and monsoon run-off contributed to surface-water buoyancy changes at times of sapropel deposition, and their relative influences differed per sapropel case, depending on their magnitudes. Sea-level rise was clearly important for sapropel S1, whereas monsoon forcing was more ...
format Article in Journal/Newspaper
author Grant, K.M.
Grimm, R.
Mikolajewicz, U.
Marino, G.
Ziegler, M.
Rohling, E.J.
spellingShingle Grant, K.M.
Grimm, R.
Mikolajewicz, U.
Marino, G.
Ziegler, M.
Rohling, E.J.
The timing of Mediterranean sapropel deposition relative to insolation, sea-level and African monsoon changes
author_facet Grant, K.M.
Grimm, R.
Mikolajewicz, U.
Marino, G.
Ziegler, M.
Rohling, E.J.
author_sort Grant, K.M.
title The timing of Mediterranean sapropel deposition relative to insolation, sea-level and African monsoon changes
title_short The timing of Mediterranean sapropel deposition relative to insolation, sea-level and African monsoon changes
title_full The timing of Mediterranean sapropel deposition relative to insolation, sea-level and African monsoon changes
title_fullStr The timing of Mediterranean sapropel deposition relative to insolation, sea-level and African monsoon changes
title_full_unstemmed The timing of Mediterranean sapropel deposition relative to insolation, sea-level and African monsoon changes
title_sort timing of mediterranean sapropel deposition relative to insolation, sea-level and african monsoon changes
publishDate 2016
url https://eprints.soton.ac.uk/394375/
https://eprints.soton.ac.uk/394375/1/Grant%2520et%2520al%25202016_JQSR-D-15-00402R1.pdf
genre North Atlantic
genre_facet North Atlantic
op_relation https://eprints.soton.ac.uk/394375/1/Grant%2520et%2520al%25202016_JQSR-D-15-00402R1.pdf
Grant, K.M., Grimm, R., Mikolajewicz, U., Marino, G., Ziegler, M. and Rohling, E.J. (2016) The timing of Mediterranean sapropel deposition relative to insolation, sea-level and African monsoon changes. Quaternary Science Reviews, 140, 125-141. (doi:10.1016/j.quascirev.2016.03.026 <http://dx.doi.org/10.1016/j.quascirev.2016.03.026>).
op_doi https://doi.org/10.1016/j.quascirev.2016.03.026
container_title Quaternary Science Reviews
container_volume 140
container_start_page 125
op_container_end_page 141
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