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| Marr, Julene P.; Carter, Lionel; Bostock, Helen C.; Bolton, Annette; Smith, Euan. |
| In situ measurements of Mg/Ca, Zn/Ca, Mn/Ca, and Ba/Ca in Globigerinoides bulloides and Globigerina ruber from southwest Pacific core top sites and plankton tow are reported and their potential as paleoproxies is explored. The modern samples cover 20 degrees of latitude from 34 degrees S to 54 degrees S, 7-19 degrees C water temperature, and variable influence of subantarctic (SAW) and subtropical (STW) surface waters. Trace element signatures recorded in core top and plankton tow planktic foraminifera are examined in the context of the chemistry and nutrient profiles of their modern water masses. Our observations suggest that Zn/Ca and Mn/Ca may have the potential to trace SAW and STW. Intraspecies and interspecies offsets identified by in situ... |
| Tipo: Text |
Palavras-chave: Mg; Ca; Mn; Ca; Ba; Ca; Zn; Ca; Southwest Pacific Ocean; Globigerina bulloides; Globigerinoides ruber; Surface ocean; Stratification; Temperature; Nutrient. |
| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00264/37528/35765.pdf |
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| Schmittner, Andreas; Bostock, Helen C.; Cartapanis, Olivier; Curry, William B.; Filipsson, Helena L.; Galbraith, Eric D.; Gottschalk, Julia; Carlos Herguera, Juan; Hoogakker, Babette; Jaccard, Samuel L.; Lisiecki, Lorraine E.; Lund, David C.; Martinez-mendez, Gema; Lynch-stieglitz, Jean; Mackensen, Andreas; Michel, Elisabeth; Mix, Alan C.; Oppo, Delia W.; Peterson, Carlye D.; Repschlaeger, Janne; Sikes, Elisabeth L.; Spero, Howard J.; Waelbroeck, Claire. |
| The carbon isotope composition (C-13) of seawater provides valuable insight on ocean circulation, air-sea exchange, the biological pump, and the global carbon cycle and is reflected by the C-13 of foraminifera tests. Here more than 1700 C-13 observations of the benthic foraminifera genus Cibicides from late Holocene sediments (C-13(Cibnat)) are compiled and compared with newly updated estimates of the natural (preindustrial) water column C-13 of dissolved inorganic carbon (C-13(DICnat)) as part of the international Ocean Circulation and Carbon Cycling (OC3) project. Using selection criteria based on the spatial distance between samples, we find high correlation between C-13(Cibnat) and C-13(DICnat), confirming earlier work. Regression analyses indicate... |
| Tipo: Text |
Palavras-chave: Carbon; Isotopes; Benthic; Foraminifera; Calibration. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00661/77326/78788.pdf |
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| Reeves, Jessica M.; Bostock, Helen C.; Ayliffe, Linda K.; Barrows, Timothy T.; De Deckker, Patrick; Devriendt, Laurent S.; Dunbar, Gavin B.; Drysdale, Russell N.; Fitzsimmons, Kathryn E.; Gagan, Michael K.; Griffiths, Michael L.; Haberle, Simon G.; Jansen, John D.; Krause, Claire; Lewis, Stephen; Mcgregor, Helen V.; Mooney, Scott D.; Moss, Patrick; Nanson, Gerald C.; Purcell, Anthony; Van Der Kaars, Sander. |
| The tropics are the major source of heat and moisture for the Australasian region. Determining the tropics' response over time to changes in climate forcing mechanisms, such as summer insolation, and the effects of relative sea level on exposed continental shelves during the Last Glacial period, is an ongoing process of re-evaluation. We present a synthesis of climate proxy data from tropical Australasia spanning the last 30,000 years that incorporates deep sea core, coral, speleothem, pollen, charcoal and terrestrial sedimentary records. Today, seasonal variability is governed largely by the annual migration of the inter-tropical convergence zone (ITCZ), influencing this region most strongly during the austral summer. However, the position of the ITCZ has... |
| Tipo: Text |
Palavras-chave: ITCZ; LGM; INTIMATE; Australasia; Indo-Pacific Warm Pool; Tropics; Australian monsoon. |
| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00264/37502/36909.pdf |
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| Bostock, Helen C.; Hayward, Bruce W.; Neil, Helen L.; Sabaa, Ashwaq T.; Scott, George H.. |
| This study fills an important gap in our understanding of past changes in the Southern Subtropical Front (S-STF) in the southwest Pacific Ocean. Paleo-sea surface temperatures (SST) were estimated from planktic foraminiferal census counts from cores straddling the modern S-STF in the Solander Trough, south of New Zealand. The estimated SST were compared for 6 time slices; glacial period (25-21 ka), Last Glacial Maximum (LGM; 21-18 ka), early deglaciation (18-16 ka), late deglacial/early Holocene period (14-8 ka), mid-Holocene period (8-4 ka), and late Holocene period (4-0 ka). The position of the S-STF was determined by two methods: (1) the location of the 10 degrees C isotherm and (2) the location of the highest SST gradients. These new results suggest... |
| Tipo: Text |
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| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00351/46252/46096.pdf |
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