DOI: 10.17632/8d2bhg3hpt
title: Data related to: "Variable onset of magma segregation controls contrasting geochemical patterns of mineral assemblages in fractionating alkaline volcanic systems"

description: For the description of the research hypothesis, all relevant results and the interpretation of the data, the user is referred to the linked research article.

Mineral compositions were analysed using a JEOL JXA 8230 electron probe microanalyzer in wave-length dispersive mode (Department of Geosciences, University of Tübingen). Peak count times were fixed at 10 s for light and volatile elements (e.g., Na, F), 16 s for the other major elements and 30 s for minor elements, with background count time being each half of peak count time. Calibration was carried out by synthetic and natural standards, and several peak overlap corrections (Cr V, V Ti, F Fe, F Ce, Ce Ba, Pr La, Ba Ti). An internal φ(ρz) raw data correction was performed for all analyses except the oxyspinel analyses, for which ZAF correction was applied. Specific parameters for the analytical protocols are given in Analytical_protocol_EPMA.xlsx, and all analytical results in EPMA_results.xlsx.

Trace element compositions in individual crystals of clinopyroxene, perovskite, titanite, apatite, and lileyite in the thin sections were analyzed using a Coherent GeolasHD 193 nm laser ablation system coupled with an Agilent 7900s quadrupole ICP-MS with high sensitivity s-lens configuration and operated with Pt skimmer and sampler cones (Chair of Applied Mineralogy and Economic Geology, RWTH Aachen). Instrumental accuracy was monitored by daily five-fold replicate measurements of NIST612 across the entire mass range using NIST610 as the external reference material and reference values from the GeoREM certified values database (Jochum et al., 2007; 2011). Instrument tuning was carried out daily for optimization of sensitivities, stable ablation, transport, and ionization conditions (U/Th = 1.00 ± 0.02) as well as minimalization of oxide formation (ThO/Th &lt;0.3%) and doubly charged interference production rates (Ca(II)/Ca &lt;0.3%). For mineral ablation, laser fluence was set to 4 J/cm³ and 5 or 10 Hz repetition rate at beam diameters of 24–60 µm, depending on mineral, crystal size, and constitution of the thin sections. The background signal was measured for 40 s, and the ablation time was &gt;40 s if possible.
All analytical results, lower limits of detection and uncertainties (1σ) are given in LA-ICP-MS_results.xlsx.

References:
Deer, W. A., Howie, R. A. & Zussman, J. (2009) An introduction to the rock-forming minerals, 2nd ed. Pearson/Prentice Hall, Harlow, 696 pp.
Jochum K. P., Stoll, B. & Willbold, M. (2007) Validation of LA-ICP-MS trace element analysis of geological glasses using a new solid-state 193 nm Nd:YAG laser and matrix-matched calibration. Journal of Analytical Atomic Spectrometry 22, 112–121.
Jochum, K. P., Weis, U., Stoll, B., Kuzmin, D., Yang, Q., Raczek, I., Jacob, D. E., Stracke, A., Birbaum, K., Frick, D. A., Günther, D. & Enzweiler, J. (2011) Determination of Reference Values for NIST SRM 610–617 Glasses Following ISO Guidelines. Geostandards and Geoanalytical Research 35, 397–429.