Paläozeanographische Rekonstruktion des Antarktischen Zwischenwassers im Südost-Pazifik während der letzten 1 Million Jahre
Paläontologie
Zusammenfassung der Projektergebnisse
This project has provided new insights in the role of intermediate waters in the outgassing of old-CO2 loaded waters after the last glacial period and inferences about the water mass geometry in the Southeast Pacific for the last 110 ka BP. While the main core to be worked at during the project (GeoB15020, 79 mcd) resulted in an unexpected young age (110 ka BP compared to the anticipated age of > 1 Ma) and foraminifera abundance was low, the alternative plan carried out focusing in the last 22 ka BP resulted in the interesting observations that during the last termination two pulses of low d13C waters at intermediate depths were coeval with breakdown of the stratification and increase upwelling around the Southern Ocean during approximately the Heinrich Stadial 1 and the Younger Dryas intervals. This correlation supports the existing notion that increased upwelling during the glacial terminations would bring glacially stored water back to the surface, releasing part of its CO2 to the atmosphere and transferring the rest to intermediate waters, which would transport it further north. Intermediate waters are thus an important player in this mechanism. The water mass geometry off Chile during the past 110 ka BP differ from the present one in two periods: 41-33 ka BP and 73-57 ka BP. During 41-33 ka BP, the benthic d13C record at 1947 m equals that at 3625 m, indicating older waters at mid-depths. During the period 73-57 ka BP, the benthic d13C record at 1947 m is even lower than at 3625 m indicating during this period the presence of older waters at mid-depths than in the bottom of the Chilean Basin and suggesting the existence of a floating carbon pool, as it has been postulated for the Last Glacial Maximum, during that interval.
Projektbezogene Publikationen (Auswahl)
- Did Antarctic Intermediate Water in the Southeast Pacific expanded vertically or only deepened? AGU Fall Meeting, New Orleans, USA. 11-15 Dec. 2017
Martínez-Méndez, G., Lamy, F., Mohtadi, M., Hebbeln, D.
- Last deglacial planktic and benthic foraminifera d13C records from the Southeast and Western Equatorial Pacific. Workshop Ocean Circulation and Carbon Cycling during the Last Deglaciation: regional Syntheses of Carbon Isotope Data, Corvallis, USA, 27-29 Jun. 2017
Martínez-Méndez, G., Reyes-Macaya, D., Awaluddin, M.Y., Hollstein, M., Martínez-Fontaire, C., Mohtadi, M., De Pol-Holz, R., Southon, J., Steinke, S., Hebbeln, D.
- Water mass geometry off Chile: the last deglaciation. Workshop Ocean Circulation and Carbon Cycling during the Last Last Deglaciation: regional Syntheses of Carbon Isotope Data, Cambridge, UK, 6-8 Sep. 2018
Martínez-Méndez, G., Hebbeln, D., Mohtadi, M., Lamy, F.
