Holocene and Last Glacial Maximum thermocline reconstructions in the Indo-Pacific Warm Pool
Final Report Abstract
We reconstructed Holocene and Last Glacial Maximum (LGM) thermocline profiles of the Indo-Pacific Warm Pool (IPWP) region and investigated their relations with the El Niño- Southern Oscillation (ENSO) and Australian-Asian monsoon systems. Planktonic foraminiferal stable isotope and Mg/Ca analyses of surface and thermocline dwelling planktonic foraminifers as well as assemblage counts in 24 cores from ODP, R/V „Sonne“ and R/V „Marion Dufresne“ cruises provide a comprehensive regional coverage of the IPWP that allowed three-dimensional thermocline reconstructions for three critical timeslices (Recent, early Holocene precession maximum, and LGM). We estimated LGM and early Holocene temperatures and salinities of sea surface and thermocline waters in the IPWP region and computed regional maps of temperature differences between the LGM, the early Holocene and the late Holocene. This dataset significantly improves spatial coverage of SST reconstructions and allows a first estimate of thermocline depths in the IPWP region for the early Holocene and LGM. Vertical profiles of the upper water column within the IPWP are related to to circulation changes (intensity and structure of the Indonesian Throughflow), state of ENSO and Australian-Asian monsoonal wind and precipitation patterns. Main results are: 1) First evidence for abrupt thermocline cooling in the Indonesian Throuflow (ITF) outflow area around 9.5 ka, when a marine connection between the Soutch China Sea and the Java Sea was established. We hypothesize, that this thermocline cooling is related to the establishement of a freshwater plug at the southern end of the Makassar Strait, which changed the vertical structure of the ITF towards a cool thermocline flow as it is today. 2) Significant glacial differences in sea surface salinity between Western Pacific marginal seas north and south of the equator, which were related to a shift in monsoonal precipitation patterns and position of the intertropical convergence zone.
Publications
- 2008. Indonesian Throughflow variability over the last 140 kyr: Temperature and precipitation proxy records from the Timor Sea. Oral Presentation, AGU Fall Meeting San Francisco
Kuhnt, W., Holbourn, A., Xu, J., Bolliet, T., Duerkop, A., Nuernberg, D., Zuraida, R., Andersen, N.
- Changes in the thermocline structure of the Indonesian outflow during Terminations I and II. Earth and Planetary Science Letters 273 (2008) 152-162
Xu, J., Holbourn, A., Kuhnt, W., Jian, Z., & Kawamura, H.
- 2009. Indonesian Throughflow variability over the last 140 kyr. Oral Presentation, Conference on Southeast Asian Gateway Evolution (SAGE), 15.-17.9. 2009. Royal Holloway, University of London, UK
Holbourn, A., Kuhnt, W., Xu, J.
- 2009. Monsoon variability over the Timor Sea and NW Australia during the last two glacial cycles. Oral Presentation, Conference on Southeast Asian Gateway Evolution (SAGE), 15.-17.9. 2009. Royal Holloway, University of London, UK
Kuhnt, W., Holbourn, A., Xu, J.
- 2009. Upper Ocean Spatial Variability in the Indo-Pacific Warm Pool during the Late Holocene, Early Holocene and Last Glacial Maximum. Poster Presentation, AGU Fall Meeting San Francisco
Xu, J., Kuhnt, W. Holbourn, W., Andersen, N.
