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| Khider, D.; Stott, L. D.; Emile-geay, J.; Thunell, R.; Hammond, D. E.. |
| We present a reconstruction of El Nino Southern Oscillation (ENSO) variability spanning the Medieval Climate Anomaly (MCA, A. D. 800-1300) and the Little Ice Age (LIA, A. D. 1500-1850). Changes in ENSO are estimated by comparing the spread and symmetry of delta O-18 values of individual specimens of the thermocline-dwelling planktonic foraminifer Pulleniatina obliquiloculata extracted from discrete time horizons of a sediment core collected in the Sulawesi Sea, at the edge of the western tropical Pacific warm pool. The spread of individual delta O-18 values is interpreted to be a measure of the strength of both phases of ENSO while the symmetry of the delta O-18 distributions is used to evaluate the relative strength/ frequency of El Ni o and La Ni a... |
| Tipo: Text |
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| Ano: 2011 |
URL: https://archimer.ifremer.fr/doc/00227/33814/32488.pdf |
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| Cronin, T. M.; Vogt, P. R.; Willard, D. A.; Thunell, R.; Halka, J.; Berke, M.; Pohlman, J.. |
| The largest abrupt climatic reversal of the Holocene interglacial, the cooling event 8.6 - 8.2 thousand years ago (ka), was probably caused by catastrophic release of glacial Lake Agassiz-Ojibway, which slowed Atlantic meridional overturning circulation (AMOC) and cooled global climate. Geophysical surveys and sediment cores from Chesapeake Bay reveal the pattern of sea level rise during this event. Sea level rose similar to 14 m between 9.5 to 7.5 ka, a pattern consistent with coral records and the ICE- 5G glacio-isostatic adjustment model. There were two distinct periods at similar to 8.9 - 8.8 and similar to 8.2 - 7.6 ka when Chesapeake marshes were drown as sea level rose rapidly at least similar to 12 mm yr(-1). The latter event occurred after the 8.6... |
| Tipo: Text |
Palavras-chave: Sea level rise; Holocene; 8.2 ka event. |
| Ano: 2007 |
URL: https://archimer.ifremer.fr/doc/00235/34644/33009.pdf |
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| Pichevin, L. E.; Ganeshram, R. S.; Geibert, W.; Thunell, R.; Hinton, R.. |
| In large swaths of the ocean, primary production by diatoms may be limited by the availability of silica, which in turn limits the biological uptake of carbon dioxide. The burial of biogenic silica in the form of opal is the main sink of marine silicon. Opal burial occurs in equal parts in iron-limited open-ocean provinces and upwelling margins, especially the eastern Pacific upwelling zone. However, it is unclear why opal burial is so effcient in this margin. Here we measure fluxes of biogenic material, concentrations of diatom-bound iron and silicon isotope ratios using sediment traps and a sediment core from the Gulf of California upwelling margin. In the sediment trap material, we find that periods of intense upwelling are associated with transient... |
| Tipo: Text |
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| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00290/40119/39246.pdf |
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