ADVANCING STANDARDIZATION OF CARBONATE LA-ICP-MS ANALYSES USING A SPELEOTHEM SAMPLE FROM THE TROPICS

Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) is a micro-analytical method to discern sub-mm variability in trace element concentrations in a plethora of geologic samples. Multiple studies using LA-ICP-MS techniques in speleothems, which are cave carbonate samples, investigate this variability in trace elements (normalized to ⁴³Ca) and are oftentimes paired with traditional stable isotope data (ẟ¹³C and ẟ¹⁸O). This multi-proxy approach of pairing trace elements and stable isotopes aides our understanding in the processes dictating trends and variability in hydroclimate that drive changes in the proxy measurements. However, a protocol for precise and accurate LA-ICP-MS analyses is required to constrain analytical problems such as matrix effects, molecular interferences, and elemental fractionation.

In this contribution, we conduct trace element (chalcophile, siderophile, lithophile elements) analyses of a speleothem sample, SR-02, collected from the Puerto Princesa Subterranean River National Park in Palawan, Philippines (10.2°N, 118.9°E). We calibrate the raw data using a glass standard reference material (NIST-612), a material commonly used in many speleothem time series studies, and a carbonate standard reference material (MACS-3). Our correlation coefficients and principal component analyses suggest that the trace element trends are not sensitive to either of the two standard reference material used for calibration. However, the distribution and ⁴³Ca normalized concentrations of the trace elements are sensitive to the choice of standard reference material. We also conduct LA-ICP-MS and solution based ICP-OES on two internal carbonate pressed pellet samples to further assess the use of a glass standard on carbonate matrix samples.