Trace element analyses (Na, Mg, Al, P, Sr, Y, Ba, Pb, U) carried out by Laser Ablation Inductively Coupled Plasma Mass Spectroscopy on subglacial calcite from the Elephant Moraine

Brief description

This dataset relates to trace element (TE) analyses of

Sample PRR-13055
Sample PRR-13081
Sample PRR-16794
Sample PRR-39222

The dataset relates to:

Images of the samples are archived in: https://data.aad.gov.au/metadata/AAS_4558_Subglacial_Carbonates_Samples

Trace element analyses (Na, Mg, Al, P, Sr, Y, Ba, Pb, U) were carried out carried out at the School of Earth Sciences (now School of Geography, Earth and Atmospheric Sciences) of the University of Melbourne by using a 193 nm ArF excimer laser-ablation system coupled to an Agilent 7700 quadrupole ICPMS. Details of the analytical procedure can be found in Woodhead et al. (2007).
Element concentrations were measured from the pre-ablated surface by using a rectangular (200 µm x 30 µm) laser spot shape scanned perpendicular to the inferred vertical accretion axis of the sample.
Measurements were carried out at a speed of 20 µm/s and a laser pulse rate of 10 Hz, generating data points every 8 micrometers and then averaged over 5 points for a final spatial resolution of 40 micrometers.
The samples and number of points (each point is the average of five measurements) are reported below (EM is the Laboratory label for Elephant Moraine):
Sample EM-13055. (PRR 13055): 1575 points;
Sample EM-13081 (PRR 13081): 2253 points;
Sample EM-16794 (PRR 16794): 641 points;
Sample EM-39222 (PRR 39222): 1439 points;

The Analyses were conducted on two parallel scans repeated at a lateral offset of 5 mm. The repeated tracks allowed the identification of outliers caused by photomechanic ablation artifacts, which were then removed from the data.
Quantification was carried out using NIST610 (Mg) and NIST612 (all other elements) glass as external standard. Raw spectrometry data were then reduced using Iolite software and internally normalized to 43Ca.

Sample PRR 39222, PRR 13081, PRR 13055 consist of black calcite, similar to that of sample PRR 23259, whose petrographic characteristics are archived in:

https://data.aad.gov.au/metadata/AAS_4558_optical_microscopy


Additional chemical data coupled with back-scattered electron (BSE) imaging of the specimens consisting of black calcite are stored in:

https://data.aad.gov.au/metadata/AAS_4558_Microprobes

Please, note that due to the limited quantity of samples, microscopy, microprobe isotope and laser ablation ion coupled plasma mass spectrometry (LA-ICP-MS) analyses had to be carried out on different specimens, to allow a minimum of preservation for future research. Of all the black calcites samples, PRR 23259 and PR 39222, which are very similar in their morphological and petrographic aspects, remains as the exemplar for all black calcites of the Elephant Moraine.
All these black calcite samples consisting of columnar crystals have radiometric (U-series) ages spanning from ca. 250,000 to (possibly) greater than 500,000 years.

Sample PRR 16794 is a white calcite, dated ca. 194,000 years. Its description can be found in Blackburn et al., 2020.