PALEO SEA LEVELS RECONSIDERED FROM DIRECT OBSERVATION OF PALEOSHORELINE POSITION DURING GLACIAL MAXIMA (FOR THE LAST 500,000 YR)

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dc.contributor.author Rabineau M.
dc.contributor.author Berné S.
dc.contributor.author Olivet J.-L.
dc.contributor.author Aslanian D.
dc.contributor.author Guillocheau F.
dc.contributor.author Joseph P.
dc.date.accessioned 2024-09-04T09:55:32Z
dc.date.available 2024-09-04T09:55:32Z
dc.date.issued 2006
dc.identifier https://www.elibrary.ru/item.asp?id=31382704
dc.identifier.citation Earth and Planetary Science Letters, 2006, 252, 1-2, 119-137
dc.identifier.issn 0012-821X
dc.identifier.uri https://repository.geologyscience.ru/handle/123456789/44899
dc.description.abstract The drastic climatic changes which characterise the cooling trend of the last few million years of Earth history led to variations in eustatic sea level that had tremendous impact on the geology and ecology of continental margins. Reconstructing a sea-level curve back in time is not an easy task. Observations of shoreline positions are always a local measurement of Relative Sea Level that needs to be corrected from the effect of tectonic and thermal subsidence, sediment loading, compaction and glacio-hydro isostasy. Extensive studies have been done for the last deglaciation and for the last 100,000 yr cycle. But very few studies deal with position of sea level during earlier cycles, simply because conditions are very rarely favourable for the preservation of such witnesses. The shelf of the Golfe du Lion (Western Mediterranean) reveals a unique record of shoreline paleopositions during glacial maxima of at least the last five circa 100 kyr glacial/interglacial cycles. In fact it is the entire glacial deltaic lobe of up to 50 m thick (from delta front or shoreface to prodelta) that has been preserved in place and which provides direct and independent constraints for relative sea-level minima. We measure a relative sea level of: - 112m, - 128, - 134, - 246 and - 262 m for MIS 2, 6, 8, 10 and 12 respectively. After corrections taking into account postdepositional movement of strata (subsidence), we find, that sea level dropped to a depth of - 102 ± 6 m during the last three glaciations (MIS2, MIS6, MIS8) but reached exceptionally low values of more than - 150 ± 10 m during the preceding glaciations MIS10 and MIS 12 at about 340 and 434 kyr BP. This general time framework and sedimentological interpretation has been confirmed by preliminary results from two deep drillings during the PROMESS cruise (july 2004), which validate our methodology. However, no detailed and absolute datings of such witnesses are available so far, so that we cannot prove that these levels are the lowest ever reached during each glacials, but they correspond undoubtedly to the last preserved shoreface before rapid sea-level rise. We also suggest that the abrupt change in sea-level maxima might be the overprint of 400 kyr orbital periodicity cycles. Last but not least, these results prove that the Golfe du Lion is indeed a unique laboratory to study paleoclimates and sea-level variations on a larger time scale. Further work is needed for a complete glacio-hydro-sedimento isostatic modelling of each sequence and each glacial to further constraint local sea level versus global sea level and quantify, in particular the relative effect of glacio-hydro isostatic effect (which differ according to ice sheet extend) but also of erosion-sedimentation isostatic effect (erosion on land and deposition on the outer shelf and slope). © 2006 Elsevier B.V. All rights reserved.
dc.subject CLIMATIC CYCLES
dc.subject GLACIAL MAXIMA
dc.subject GLACIO-EUSTATISM
dc.subject GOLFE DU LION
dc.subject GULF OF LIONS
dc.subject MEDITERRANEAN SEA
dc.subject SEA-LEVEL AMPLITUDES
dc.subject SEA-LEVEL CHANGES
dc.subject SHORELINE POSITION
dc.subject SUBSIDENCE
dc.title PALEO SEA LEVELS RECONSIDERED FROM DIRECT OBSERVATION OF PALEOSHORELINE POSITION DURING GLACIAL MAXIMA (FOR THE LAST 500,000 YR)
dc.type Статья
dc.identifier.doi 10.1016/j.epsl.2006.09.033


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