EXAMINATION OF SURFACE FEATURES AND MINERALOGY OF QUARTZ GRAINS FROM WOLFE CREEK CRATER, WESTERN AUSTRALIA TO DETERMINE PROVENANCE AS AN INDICATOR OF PALEOCLIMATE

Evidence from the Australian interior suggests that the intensity of the Australian summer monsoon has changed significantly through the late Pleistocene (Magee et al., 1998, Johnson et al., 1999). We seek to develop continuous records of the Australian monsoon from northern Australia in order to quantify the variability in the monsoon prior to and post human arrival onto the continent nearly 60,000 years ago (Roberts et al., 1990). We are examining the mineralogy (using SEM-EDS and standard petrographic techniques) and aeolian textures (using SEM) of a 10 m sediment core taken from a sand-dune at the Wolfe Creek Crater National Park, Western Australia. We hypothesize that the mineralogy and textural analysis of the sand grains will provide indicators of provenance and length of sediment transport and will vary down-core in response to fluctuations in the intensity of the Australian summer monsoon. Periods of intense summer monsoon should be represented by local provenance and short-transport distances due to the stabilizing effect of vegetation on the land surface, for example. Preliminary SEM and petrographic analysis indicates that the grain size and shape vary down core, in accord with prediction. The type and amount of silica coating and the types of aeolian features (i.e., pitting, chemical dissolution) vary, as well. Preliminary luminescence dates at the core bottom (i.e., approx. 10 m depth) indicate the sediments are nearly 300,000 years old.