Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.13/923684

OpenURL Link
Title
Evidence for Holocene changes in Australian-Indonesian monsoon rainfall from stalagmite trace element and stable isotope ratios
Author/Creator
Griffiths, Michael L.;  Drysdale, Russell N.;  Suwargadi, Bambang W.;  Gagan, Michael K.;  Frisia, Silvia;  Zhao, Jian-Xin;  Ayliffe, Linda K.;  Hantoro, Wahyoe S.;  Hellstrom, John C.;  Fischer, Matthew J.;  Feng, Yue-Xing
Institution
The University of Newcastle. Faculty of Science & Information Technology, School of Environmental and Life Sciences
Description
Trace element and stable isotope ratios from an active stalagmite (LR06-B1) recovered from Liang Luar Cave on the island of Flores (eastern Indonesia) are used to reconstruct the position of the austral summer inter-tropical convergence zone and Australian-Indonesian summer monsoon variability during the Holocene. Uranium-series dating of the stalagmite shows that it commenced growth 12,640 years ago , with hiatuses spanning 8,560 to 6,420 and 3,670 to 2,780 years ago. Stalagmite Mg/Ca and Sr/Ca ratios correlate significantly with one another, and with δ¹⁸O and δ¹³C, throughout the record. This suggests that the Mg/Ca and Sr/Ca ratios are dominated by prior calcite precipitation, a process whereby degassing in the vadose zone during periods of low recharge causes deposition of calcite and disproportionate loss of Ca²⁺ ions (relative to Mg²⁺ and Sr²⁺) ‘upstream’ of the stalagmite. The degree of initial ²³⁴U/²³⁸U disequilibrium also appears to have been controlled by recharge to the overlying aquifer. Together with the Mg/Ca, Sr/Ca, and δ¹⁸O values, the initial uranium isotope activity ratios ([²³⁴U/²³⁸U]I) imply a generally drier early Holocene, coincident with a lower sea level and lower Southern Hemisphere summer insolation. Comparison of speleothem δ18O time-series from Flores and Borneo shows that they vary in unison for much of the Holocene. However, there is a significant decrease in the Borneo δ¹⁸O record ~6,000 to 4,000 years ago that does not occur in the Flores record. This anomaly may be related to a change in the Australian-Indonesian summer monsoon circulation in response to a protracted positive phase of the Indian Ocean Dipole. Under this scenario, stronger upwelling off of western Indonesia would, based on present-day effects, result in reduced summer convective activity over Flores and a subsequent northward shift of the intertropical convergence zone.
Relation
Earth and Planetary Science Letters Vol. 292, Issue 1-2, p. 27-38
Publisher Link
http://dx.doi.org/10.1016/j.epsl.2010.01.002
Date
2010
Publisher
Elsevier
Keyword(s)
trace elements;  speleothem;  stable isotopes;  Australian–Indonesian summer monsoon;  inter-tropical convergence zone (ITCZ);  Indian Ocean Dipole (IOD)
Resource Type
journal article
Identifier
http://hdl.handle.net/1959.13/923684
Identifier
ISSN:0012-821X
Reviewed
Reviewed
16 Visitors 18 Hits 0 Downloads
Save/E-mail Citation
Citation Format
E-mail Address
Subject
"Earth and Planetary Science Letters"
 
OR