Seasonal to interannual climate variability in the tropical southwest Pacific during the last deglaciation - Monthly resolved reconstructions from Great Barrier Reef corals
Zusammenfassung der Projektergebnisse
This pilot project investigated the potential of fossil corals drilled during IODP Expedition 325 to the Great Barrier Reef for the reconstruction of seasonality, interannual climate variability, and mean climate change in the tropical southwest Pacific Ocean since the Last Glacial Maximum (LGM). Screening for diagenesis revealed no significant alteration of coral skeletons. Analyses of Sr/Ca and oxygen isotope ratios were performed on massive Isopora, corymbose Acropora, Faviidae, and Porites corals at approximately monthly resolution. U-series dating by collaborating Expedition 325 science party members revealed that the investigated corals represent important time intervals of the last deglaciation and the LGM. For the first time, very clear annual cycles of sea surface temperature could be reconstructed from an Acropora coral of LGM age. However, reconstructed annual cycles from Isopora corals, which represent the majority of the available coral material, were less clear, probably reflecting a more complex calcification pattern of their skeleton compared to other massive corals (e.g., Porites). All investigated specimens were relatively small, providing paleoclimatic snapshots of a few years only, which is definitely too short to reconstruct the variability of climate phenomena such as the El Niño-Southern Oscillation. However, the mean Sr/Ca and oxygen isotope ratios of the individual coral colonies clearly indicate the expected overall trend of deglacial warming since the LGM. Such results will complement reconstructions of tropical Pacific temperature change during the last deglaciation from marine sediments, which are primarily located in the equatorial western and eastern regions of the basin. Clearly, the LGM coral material that has been drilled by IODP Expedition 325 in the Great Barrier Reef is unique with respect to the entire Pacific region. Collaborative work among the Expedition 325 Science Party members in order to robustly interpret the preliminary results generated by the large number of individual labs is underway. Cotteril, C., Felis, T. (2011) Unlocking climate and sea level secrets since the Last Glacial Maximum – Results from the IODP Great Barrier Reef Environmental Changes Expedition. Press Conference at European Geosciences Union General Assembly 2011, Vienna/Austria. http://www.cntv.at/EGU2011/index.php?modid=18&a=show&pid=137
Projektbezogene Publikationen (Auswahl)
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(2011) IODP Expedition 325 to the Great Barrier Reef: climate and sea level changes since the Last Glacial Maximum, IODP/ICDP Colloquium Münster 2011 – Cruise Reports, p. 20
Felis, T., Gischler, E., and the Expedition 325 Scientists
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(2011), IODP Expedition 325: Great Barrier Reef reveals past sea-level, climate and environmental changes since the last ice age, Scientific Drilling, 12, 32-45
Yokoyama, Y., Webster, J.M., Cotterill, C., Braga, J.C., Jovane, L., Mills, H., Morgan, S., Suzuki, A., and the IODP Expedition 325 Scientists including Felis, T.
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(2011), Proc. IODP, 325: Tokyo (Integrated Ocean Drilling Program Management International, Inc.)
Webster, J.M., Y. Yokoyama, C. Cotterill, and the Expedition 325 Scientists including Felis, T.
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(2012), Coral records of climate change since the Last Glacial Maximum – IODP Expedition 325 to the Great Barrier Reef, IODP/ICDP Colloquium Kiel 2012 – Abstracts, 44-46
Felis, T., Thomas, A.L., Yokoyama, Y., Webster, J.M., and Expedition 325 Paleoclimate and Dating Groups
