Late Pleistocene onset of monsoonal rain and abrupt strengthening of ENSO 3,900 cal yrs BP recorded by diatomaceous sediments from dry tropical Australia

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dc.contributor.authorWust, RAJen_AU
dc.contributor.authorShemesh, Aen_AU
dc.contributor.authorRidd, Pen_AU
dc.contributor.authorStephenson, Jen_AU
dc.contributor.authorJacobsen, GEen_AU
dc.contributor.authorSmith, AMen_AU
dc.date.accessioned2020-10-26T00:08:01Zen_AU
dc.date.available2020-10-26T00:08:01Zen_AU
dc.date.issued2009-05-15en_AU
dc.date.statistics2020-10-26en_AU
dc.description.abstractA continuous diatomaceous sediment record from dry tropical Queensland, Australia, provides new evidence for rapid precipitation variations over the last 14,000 cal years. Lava flows from Toomba Volcano formed a unique runoff-isolated lake system ~13,600 cal yrs BP that contains 5.5 m thick purely diatomaceous debris. High precipitation during shortly after the development of the lake system supports other studies that the monsoonal system developed around 13,000 cal yrs BP. Geochemical data and isotope analysis of the diatoms reveal that primary productivity was high during the onset of the deposit with little changes until the mid Holocene, when abrupt moisture regime changes occurred ~6,000 years ago. Prior to that, precipitation across this present-day dry tropical site must have been plenty to sustain a perennial lake system. Furthermore, oxygen isotope data of the diatoms indicates that changes in moisture source took place progressively shortly after 9,000 years ago and lasted until about 6,500 years when abrupt shifts in source occurred until 6,000 years ago. Since then, isotopic values remained similar with to periods of rapid changes between 3,000-1,800 and ~400-200 cal yrs BP (Little Ice Age). Trace elemental composition of the record provides further evidence for marked changes of the atmospheric composition ~3,900 yrs BP and may represent the timing of the drying of the Australian continent (enhanced erosion of top soils), which most likely signifies the intensification of the El NiƱo Southern Oscillation (ENSO) in this region. The interpretation is supported by previous studies from corals from tropical Pacific and marine sediments from, for example, the Cariaco Basin off the Venezuelan coast. At Cariaco, the changes were interpreted to be due to the onset and intensification of ENSO. These studies suggested that over the last 4000 years, strong ENSO with increasing variability dominated the monsoonal regions. In summary, our record shows that the dry tropics received more precipitation during the late Pleistocene and early Holocene than during the late Holocene. These findings are similar to findings from the wet tropical NE-Australia. However, our record shows a marked collapse of the ocean/atmospheric system in the low latitudes and an intensification of ENSO during the latter part of the Holocene round 3,900 cal yrs Bp with several marked climatic shifts since then, with the last one occurring during the Little Ice Age.en_AU
dc.identifier.citationWust, R. A. J., Shemesh, A., Ridd, P., Stephenson, J., Jacobsen, G., & Smith, A. (2009). Late Pleistocene onset of monsoonal rain and abrupt strengthening of ENSO 3,900 cal yrs BP recorded by diatomaceous sediments from dry tropical Australia. Paper presented at the Past Climates meeting, Wellington New Zealand, May 15-17, 2009.en_AU
dc.identifier.conferenceenddate17 May 2009en_AU
dc.identifier.conferencenamePast Climates meetingen_AU
dc.identifier.conferenceplaceWellington, New Zealanden_AU
dc.identifier.conferencestartdate15 May 2009en_AU
dc.identifier.urihttps://apo.ansto.gov.au/dspace/handle/10238/9943en_AU
dc.language.isoenen_AU
dc.publisherGNS Scienceen_AU
dc.subjectQueenslanden_AU
dc.subjectAustraliaen_AU
dc.subjectTropical regionsen_AU
dc.subjectVolcanoesen_AU
dc.subjectGeochemistryen_AU
dc.subjectIsotopesen_AU
dc.subjectOxygen isotopesen_AU
dc.subjectLavaen_AU
dc.subjectLakesen_AU
dc.subjectErosionen_AU
dc.subjectSoilsen_AU
dc.subjectSouthern Oscillationen_AU
dc.subjectQuaternary perioden_AU
dc.subjectClimatic changeen_AU
dc.titleLate Pleistocene onset of monsoonal rain and abrupt strengthening of ENSO 3,900 cal yrs BP recorded by diatomaceous sediments from dry tropical Australiaen_AU
dc.typeConference Presentationen_AU
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