Backscattered electron image (BSE) images of ocean island basalt samples from four volcanic systems in Iceland (Holuhraun, Skuggafjoll, Laki and Eyjafjallajokull) and two eruption sites on Pico Island in the Azores (samples PI-011 and PI-041). These samples are described in the following manuscript: Neave, David A., Alexander G. Stewart, Margaret E. Hartley, and Olivier Namur. ‘Iron Valence Systematics in Clinopyroxene Crystals from Ocean Island Basalts’. Contributions to Mineralogy and Petrology 179 (2024): 67. https://doi.org/10.1007/s00410-024-02144-x.

Compositional data of clinopyroxene crystals standards analysed by electron probe microanalyses for major element oxides and by Mossbauer spectroscopy for iron valence and unknown clinopyroxene crystals from Iceland and the Azores . These data were collected in support of research described in the following preprints: https://doi.org/10.31223/X5CT03 and https://doi.org/10.31223/X5N959

Mineral chemistry of volcaniclasts from IODP Site 1438 drilled during exp.351 in the Amami Basin, W.Pacific Ocean. This data includes mineral chemistry of mafic minerals determined by electron microprobe at University of Leeds.

EPMA (Electron probe microanalysis) major element analyses of clinopyroxene, olivine, amphibole and glass from lava and tephra samples of the 2021 Tajogaite eruption. LAICPMS (Laser Ablation Inductively Coupled Plasma Mass Spectrometry) trace element analyses of selected clinopyroxene from the eruption sequence.

We collected major element, trace element and Nd isotopes of cumulate plagioclase and clinopyroxene in lower crustal gabbros from Hess Deep oceanic crust (~2°15'N, 101°30'W) to investigate the Nd isotopic heterogeneity of melts delivered to a complete section of Hess Deep oceanic crust, accreted at the fast-spreading (133 mm/yr) East Pacific Rise (EPR). These data are presented in Cooper et al. (2025) (https://doi.org/10.1130/G52872.1). Elemental maps of 58 samples were initially obtained prior to selecting a subset of 25 samples for in-situ microanalysis. We targeted the Nd isotope record of cumulate plagioclase and clinopyroxene from lower crustal gabbro samples, representing early crystallisation products of melts delivered to the crust. These samples were collected in several expeditions: Ocean Drilling Program (ODP) Leg 147; RSS James Cook cruise JC21; Integrated Ocean Drilling Program (IODP) Expedition 345 (Site U). Combined, these studies provide the most complete composite section of fast-spreading EPR crust to date (stratigraphic depth of 4350 m to 25 m). In our study, we selected 25 samples for in situ Nd isotope microanalysis, covering the range of mineralogy and textural diversity, and over the full stratigraphic depth. For a comparison to local MORB compositions, we selected a set of 13 upper-crustal sheeted dikes collected on the RSS James Cook cruise JC21. Our data reveal that the mantle is heterogeneous at the scale of melt extraction, and the crystal record from the lower crust shows greater 143Nd/144Nd heterogeneity than the overlying MORB. Hence, Pacific MORBs do not reflect the full heterogeneity of their mantle source, and some aggregation of melts occurs within the crust. Data was collected between 2020 and 2023 by George Cooper, Johan Lissenberg and Max Jansen at Cardiff University, UK, as part of NERC Grant NE/T000317/1:HiDe: A Highly Heterogeneous Depleted Upper Mantle? Mineral isotopic analyses were performed on a Thermo Scientific TRITON Plus at the Vrije Universiteit in Amsterdam. The long-term average and reproducibility (2019–2022) for the JNdi-1 standard is 0.512094 ± 0.000011 2 SD (standard deviation; n = 28) with 1011Ω resistors (used for clinopyroxene) and 0.512105 ± 0.000044 2 SD (n = 45) with four 1013Ω resistors (used for plagioclase). Full methodology can be found within the supplemental Material of Cooper et al. (2025) at https://doi.org/10.1130/GEOL.S.28485770 The DOI is a supplement to https://doi.org/10.1130/G52872.1 Methodology: https://gsapubs.figshare.com/articles/journal_contribution/Supplemental_Material_Crustal_versus_mantle-level_aggregation_of_heterogeneous_melts_at_mid-ocean_ridges/28485770?file=52665137

Petrological and geochemical analysis of samples from Aluto volcano, Ethiopia. Data are referenced in Gleeson et al., 2017: Constraining magma storage conditions at a restless volcano in the Main Ethiopian Rift using phase equilibria models; https://doi.org/10.1016/j.jvolgeores.2017.02.026.