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| Incarbona, Alessandro; Martrat, Belen; Di Stefano, Enrico; Grimalt, Joan O.; Pelosi, Nicola; Patti, Bernardo; Tranchida, Giorgio. |
| This study analyzes coccolithophore abundance fluctuations (e. g., Emiliania huxleyi, Gephyrocapsa specimens, and Florisphaera profunda) in core MD01-2444 sediment strata retrieved at the Iberian Margin, northeastern Atlantic Ocean. Coccolithophores are calcareous nannofossils, a major component of the oceanic phytoplankton, which provide information about past ecological and climatological variability. Results are supported by data on fossil organic compounds (sea surface temperatures, alkenones, and n-hexacosan-1-ol index) and geochemical analyses (benthic delta C-13(cc) and planktonic delta O-18(cc) isotopes). Three scenarios are taken into account for this location at centennial-scale resolution over the last 70,000 years: the Holocene and the stadial... |
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| Ano: 2010 |
URL: https://archimer.ifremer.fr/doc/00231/34205/32756.pdf |
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| Urrego, Dunia H.; Hooghiemstra, Henry; Rama-corredor, Oscar; Martrat, Belen; Grimalt, Joan O.; Thompson, Lonnie; Bush, Mark B.; Gonzalez-carranza, Zaire; Hanselman, Jennifer; Valencia, Bryan; Velasquez-ruiz, Cesar. |
| We compare eight pollen records reflecting climatic and environmental change from northern and southern sites in the tropical Andes. Our analysis focuses on the last 30 000 years, with particular emphasis on the Pleistocene to Holocene transition. We explore ecological grouping and downcore ordination results as two approaches for extracting environmental variability from pollen records. We also use the records of aquatic and shoreline vegetation as markers for lake level fluctuations and moisture availability. Our analysis focuses on the signature of millennial-scale climate variability in the tropical Andes, in particular Heinrich stadials (HS) and Greenland interstadials (GI). The pollen records show an overall warming trend during the... |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00421/53285/54277.pdf |
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| Margari, Vasiliki; Skinner, Luke C.; Hodell, David A.; Martrat, Belen; Toucanne, Samuel; Grimalt, Joan O.; Gibbard, Philip L.; Lunkka, J. P.; Tzedakis, P. C.. |
| Past glacials can be thought of as natural experiments in which variations in boundary conditions influenced the character of climate change. However, beyond the last glacial, an integrated view of orbital-and millennial-scale changes and their relation to the record of glaciation has been lacking. Here, we present a detailed record of variations in the land-ocean system from the Portuguese margin during the penultimate glacial and place it within the framework of ice-volume changes, with particular reference to European ice-sheet dynamics. The interaction of orbital-and millennial-scale variability divides the glacial into an early part with warmer and wetter overall conditions and prominent climate oscillations, a transitional mid-part, and a late part... |
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| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00187/29819/28295.pdf |
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| Cisneros, Merce; Cacho, Isabel; Frigola, Jaime; Canals, Miquel; Masque, Pere; Martrat, Belen; Casado, Marta; Grimalt, Joan O.; Pena, Leopoldo D.; Margaritelli, Giulia; Lirer, Fabrizio. |
| This study presents the reconstructed evolution of sea surface conditions in the central-western Mediterranean Sea during the late Holocene (2700 years) from a set of multi-proxy records as measured on five short sediment cores from two sites north of Minorca (cores MINMC06 and HER-MC-MR3). Sea surface temperatures (SSTs) from alkenones and Globigerina bulloides Mg / Ca ratios are combined with δ18O measurements in order to reconstruct changes in the regional evaporation–precipitation (E–P) balance. We also revisit the G. bulloides Mg / Ca–SST calibration and re-adjusted it based on a set of core-top measurements from the western Mediterranean Sea. Modern regional oceanographic data indicate that Globigerina bulloides Mg / Ca is mainly controlled by... |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00333/44460/44137.pdf |
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| Margari, Vasiliki; Skinner, Luke C.; Menviel, Laurie; Capron, Emilie; Rhodes, Rachael H.; Mleneck-vautravers, Maryline J.; Ezat, Mohamed M.; Martrat, Belen; Grimalt, Joan O.; Hodell, David A.; Tzedakis, Polychronis C.. |
| The abrupt nature of warming events recorded in Greenland ice-cores during the last glacial has generated much debate over their underlying mechanisms. Here, we present joint marine and terrestrial analyses from the Portuguese Margin, showing a succession of cold stadials and warm interstadials over the interval 35–57 ka. Heinrich stadials 4 and 5 contain considerable structure, with a short transitional phase leading to an interval of maximum cooling and aridity, followed by slowly increasing sea-surface temperatures and moisture availability. A climate model experiment reproduces the changes in western Iberia during the final part of Heinrich stadial 4 as a result of the gradual recovery of the Atlantic meridional overturning circulation. What emerges is... |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00643/75476/76313.pdf |
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