Mineral geochemical analyses (core rim traverses of plagioclase and pyroxene) of samples recovered during IODP Expedition 398 (Site U1595). Site U1595 (proposed Site CSK-08B) is located in the southern basin of the Santorini caldera at 291 meters below sea level (mbsl). It was drilled in three holes (U1595A–U1595C) to a maximum recovery depth of 127.0 meters below seafloor. The data files also contain BSE images of plagioclase and pyroxene crystals that illustrate where the geochemical traverses were done. Mineral geochemical analyses and BSE images were generated by electron probe micro-analysis, using facilities at the Natural History Museum London. Data analysis was supported by NERC - UK IODP Phase 4 Moratorium Award, NERC Grant NE/X016374/1, Ralf Gertisser. For sample context, see: https://publications.iodp.org/proceedings/398/398title.html https://doi.org/10.14379/iodp.proc.398.109.2024

Chemical analysis of pyroxenes and BSE-SEM images from pumices and lava flows from Popocatepetl Volcano, Mexico. Whole rock isotope data from pumices and lava flows from Popocatepetl Volcano, Mexico.

Mineral and glass geochemical analyses (spot analyses) of samples recovered during IODP Expedition 398 (Site U1595). Site U1595 (proposed Site CSK-08B) is located in the southern basin of the Santorini caldera at 291 meters below sea level (mbsl). It was drilled in three holes (U1595A-U1595C) to a maximum recovery depth of 127.0 meters below seafloor. Some data files also contain SEM-BSE images of volcanic ash particles. Abbreviations used: n.d. = not determined; b.d. = below detection. Detection limits for volatiles in glass: Cl = 57 ppm, F = 140 ppm, S = 56 ppm Mineral and glass geochemical compositions were determined by electron probe micro-analysis, using facilities at the Natural History Museum London and at the University of Leeds. SEM-BSE images were generated at Keele University. Data analysis was supported by NERC - UK IODP Phase 4 Moratorium Award, NERC Grant NE/X016374/1, Ralf Gertisser. For sample context, see: https://publications.iodp.org/proceedings/398/398title.html https://doi.org/10.14379/iodp.proc.398.109.2024

Geochemical data has been collected on samples from new exposures of the 1883 deposits, revealed by the 2018 tsunamigenic flank collapse of Anak Krakatau, which provides improved stratigraphic context. Whole-rock data taken by X-ray Florescence shows no systematic stratigraphic correlation. Chemical data for transects across, and spot points on, plagioclase phenocrysts, including some trace element data, all obtained using Electron Probe Microanalysis (EPMA), with Backscatter electron (BSE) images of crystals, obtained using Scanning Electron Microscope, reveal complex zoning profiles. However, chemical data for transects across pyroxene phenocrysts, obtained using EPMA, show this phenocryst phase is largely unzoned. The dataset also includes chemical data for spots on Fe/Ti oxides, included on the rims of pyroxene, and obtained using EPMA. Matrix glass chemistry, obtained via EPMA, shows that the early eruptive ash is more evolved than the pyroclastic material that follows, and that there is a slight overall trend to a more homogenous, less evolved melt composition. The 1883 eruption of Krakatau was a large, cardera-forming eruption that caused approximately 36,000 fatalities. It is also the only eruption of its size to have accompanying written accounts.