A STALAGMITE RECORD OF CLIMATE VARIABILITY FROM THE LAST GLACIAL MAXIMUM THROUGH MIDDLE HOLOCENE FROM CAPE RANGE, WESTERN AUSTRALIA
Stalagmite oxygen isotopic (δ18O) values during the LGM average -6.5‰, decreased to -8.0‰ at 16 ka and increased afterwards into the Holocene, also becoming 1.5‰ lighter coincident with Heinrich Stadial 1 (HS1). One possibility for this shift during HS1 is a southward shift of the Intertropical Convergence Zone introduced significant amounts of isotopically light Australian summer monsoon rain, an interpretation supported by stalagmite time series from Ball Gown Cave, tropical Western Australia (Denniston et al., 2013, QSR, 72, 159.). Alternatively, tropical cyclone activity may have changed during this time, or a southern source also could have accounted for the depleted δ18O values during HS1. South-central Australian megalake high stands occurred during deglaciation, including HS1, and have been tied to increased winter rainfall from the southern westerlies (Cohen et al., 2012, Palaeo3, 356, 89), which could as well explain the depleted δ18O values in our data . Changes in rainfall brought by NWCB could also have accounted for the decreased δ18O values in Cape Range stalagmites during HS1 although the behavior of this system in the last glacial period is not well constrained.