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| Ronge, T. A.; Tiedemann, R.; Lamy, F.; Koehler, P.; Alloway, B. V.; De Pol-holz, R.; Pahnke, K.; Southon, J.; Wacker, L.. |
| During the last deglaciation, the opposing patterns of atmospheric CO2 and radiocarbon activities (Delta C-14) suggest the release of C-14-depleted CO2 from old carbon reservoirs. Although evidences point to the deep Pacific as a major reservoir of this C-14-depleted carbon, its extent and evolution still need to be constrained. Here we use sediment cores retrieved along a South Pacific transect to reconstruct the spatio-temporal evolution of Delta C-14 over the last 30,000 years. In similar to 2,500-3,600 m water depth, we find C-14-depleted deep waters with a maximum glacial offset to atmospheric (14)(C) (Delta Delta C-14 = -1,000%). Using a box model, we test the hypothesis that these low values might have been caused by an interaction of aging and... |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00421/53251/54716.pdf |
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| Skonieczny, C.; Mcgee, D.; Winckler, G.; Bory, A.; Bradtmiller, L. I.; Kinsley, C. W.; Polissar, P. J.; De Pol-holz, R.; Rossignol, L.; Malaizé, B.. |
| Reconstructions of past Saharan dust deposition in marine sediments provide foundational records of North African climate over time scales of 103 to 106 years. Previous dust records show primarily glacial-interglacial variability in the Pleistocene, in contrast to other monsoon records showing strong precessional variability. Here, we present the first Saharan dust record spanning multiple glacial cycles obtained using 230Th normalization, an improved method of calculating fluxes. Contrary to previous data, our record from the West African margin demonstrates high correlation with summer insolation and limited glacial-interglacial changes, indicating coherent variability in the African monsoon belt throughout the late Pleistocene. Our results demonstrate... |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00474/58554/61106.pdf |
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| Martinez-mendez, G.; Hebbeln, D.; Mohtadi, M.; Lamy, F.; De Pol-holz, R.; Reyes-macaya, D.; Freudenthal, Tim. |
| The Antarctic Intermediate Water (AAIW) is a key player in global-scale oceanic overturning processes and an important conduit for heat, fresh water, and carbon transport. The AAIW past variability is poorly understood mainly due to the lack of sedimentary archives at intermediate water depths. We present records of benthic stable isotopes from sediments retrieved with the seafloor drill rig MARUM-MeBo at 956m water depth off northern Chile (GeoB15016, 27 degrees 29.48S, 71 degrees 07.58W) that extend back to 970ka. The sediments at this site are presently deposited at the boundary between AAIW and Pacific Deep Water (PDW). For previous peak interglacials, our results reveal similar benthic C-13 values at site GeoB15016 and of a newly generated stack of... |
| Tipo: Text |
Palavras-chave: Paleoceanography; AAIW; Advection changes. |
| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00263/37459/35821.pdf |
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