2011 GSA Annual Meeting in Minneapolis (912 October 2011)
Paper No. 243-17
Presentation Time: 9:00 AM-6:00 PM

A NOVEL METHOD FOR TRACE ELEMENTAL ANALYSES OF SPELEOTHEMS USING -XRF

BUCKLES, Jessica1, ROWE, Harry2, GAO, Yongli3, CHENG, Hai4, EDWARDS, R. Lawrence4, SPRINGER, Gregory5, and HARDT, Benjamin6, (1) Earth and Environmental Sciences, University of Texas at Arlington, Box 19049, 500 Yates St, Arlington, TX 76019, buckles@uta.edu, (2) Earth and Environmental Sciences, University of Texas at Arlington, Box 19049, 500 Yates Street, Arlington, TX 76019, (3) Geosciences, East Tennessee State University, Johnson City, TN 37614, (4) Department of Geology and Geophysics, University of Minnesota, 310 Pillsbury Dr. SE, Minneapolis, MN 55455, (5) Department of Geological Sciences, Ohio Univ, 316 Clippinger, Athens, OH 45701, (6) Geology and Geophysics, University of Minnesota, 310 Pilsbury Drive SE, Minneapolis, MN 55455

Trace element ratios in speleothems (Sr/Ca, Mg/Ca, Ba/Ca) have been used to interpret the hydrogeochemical processes in the epikarst zone as well as the partitioning that occurs at the calcite-water interface. During periods of low rainfall, trace element ratios generally increase as a result of the longer residence time of water in the soil and epikarst zones. High-resolution time series analyses of these elements in speleothems provide evidence for changing paleohydrological and geochemical conditions over time.

The conventional methods of trace metal analysis of speleothems- Laser Ablation Inductively-Coupled Plasma Mass Spectrometry (LA-ICPMS) and Inductively-Coupled Plasma Optical Emission Spectroscopy (ICP-OES) have yielded many high-quality data sets. However, these methods can be expensive, time-consuming and require the destruction – either by ablation, micro-milling, or powdering – of speleothem samples. The many caveats of these conventional methods have led to the search for a viable alternative – one that will provide the same high-resolution results, but that is affordable, rapid, and non-destructive.

Presented here are preliminary results using µ-X-ray Fluorescence Spectrometry. The Brüker-AXS ARTAX µ-XRF spectrometer permits a multi-element analysis from Na to U with a spatial resolution of 70 µm. The method is non-contact and non-destructive, therefore preserving the sample for additional analyses (e.g. stable isotopes). A simple calibration method for Sr/Ca using pressed mixed powders will be described.

It will be demonstrated that µ-XRF is an important tool in trace element analysis of speleothems and a viable alternative to conventional methods. Sr/Ca ratios were obtained for multiple speleothems and serve as a preliminary test of µ-XRF suitability. Analyses of variable count times, temporal and spatial reproducibility along transects, and a comparison between µ-XRF spectra and ICP-OES spectra for the same transect of a speleothem growth axis will be presented. In addition, ARTAX multi-transect area-mapping will demonstrate trace element abundances along both calcite bands and the growth axis.

2011 GSA Annual Meeting in Minneapolis (912 October 2011)
General Information for this Meeting
Session No. 243--Booth# 83
Geochemistry (Posters)
Minneapolis Convention Center: Hall C
9:00 AM-6:00 PM, Wednesday, 12 October 2011

Geological Society of America Abstracts with Programs, Vol. 43, No. 5, p. 588

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