Plagioclase
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lectron probe analyses of the composition of plagioclase macocrysts from the 2021 eruption of the Fagradalsfjall eruption in Iceland. These were collected in profiles from rimtocore and were designed for diffusion chronometry applications. This will be published in a article (in press in late 2022) in the journal Geology and with lead author Kahl. Analyses of a secondary standard across the many days of analytical sessions are also provided.

A single Excel spreadsheet giving augiteplagioclaseplagioclase dihedral angle populations in cumulates from the Rustenberg Layered Suite of the Bushveld Igneous Complex. A document providing the background information and location of the samples used in the study. The data have been published: Holness et al. (2017) Contributions to Mineralogy and Petrology, 172:102 doi.org/10.1007/s0041001714234

Measurements of the shape and size of plagioclase and olivine grains in a suite of dolerite dykes and sills. The olivine data refer to the family of sills forming the Little Minch Sill Complex where exposed on the Isle of Skye, while the plagioclase work also includes a range of sills and dykes from all over the world. Measurments of dihedral angles at junctions between two grains of plagioclase and one of pyroxene, again in dolerites from dykes and sills, and also from the Rustenburg Suite of the Bushveld Layered Intrusion in South Africa.

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.

Geochemical analyses of melt inclusions, host minerals, and glasses from the 201415 Holuhraun eruption, Iceland. Published in: Hartley ME, Bali E, Neave DA, Maclennan J, Halldorsson SA (2018) Melt inclusion constraints on petrogenesis of the 2014–2015 Holuhraun eruption, Iceland. Contrib Mineral Petrol 173:10. doi:10.1007/s0041001714350

Data on the average aspect ratio (length/width) and average length of plagioclase grains in dykes and sills, used to demonstrate that the solidification regime is a function of the orientation of tabular intrusions. The data are written up, with publication expected in Journal of Petrology.

This is supporting data for the manuscript entitled 'DFENS: Diffusion chronometry using Finite Elements and Nested Sampling' by E. J. F. Mutch, J. Maclennan, O. Shorttle, J. F. Rudge and D. Neave. Preprint here: https://doi.org/10.1002/essoar.10503709.1 Data Set S1. ds01.csv Electron probe microanalysis (EPMA) profile data of olivine crystals used in this study. Standard deviations are averaged values of standard deviations from counting statistics and repeat measurements of secondary standards. Data Set S2. ds02.csv Plagioclase compositional profiles used in this study, including SIMS, EPMA and step scan data. Standard deviations for EPMA analyses are averaged values of standard deviations from counting statistics and repeat measurements of secondary standards. Standard deviations for SIMS and step scan analyses are based on analytical precision of secondary standards. Data Set S3. ds03.csv Angles between the EPMA profile and the main olivine crystallographic axes measured by electron backscatter diffraction (EBSD). 'angle100X' is the angle between the [100] crystallographic axis and the x direction of the EBSD map, 'angle100Y' is the angle between [100] crystallographic axis and the y direction of the EBSD map, and 'angle100Z' is the angle between the [100] crystallographic axis and the z direction in the EBSD map etc. 'angle100P' is the angle between the EPMA profile and the [100] crystallographic axis, 'angle010P' is the angle between the EPMA profile and the [010] crystallographic axis, and 'angle100P' is the angle between the EPMA profile and the [001] crystallographic axis. All angles are in degrees. Data Set S4. ds04.csv Median timescales and 1 sigma errors from the olivine crystals of this study. The +1 sigma (days) is the quantile value calculated at 0.841 (i.e. 0.5 + (0.6826 / 2)). The 1 sigma (days) is therefore the quantile calculated at approximately 0.158 (which is 1  0.841). The 2 sigma is basically the same but it is 0.5 + (0.95/2). The value quoted as the +1 sigma (error) is the difference between the upper 1 sigma quantile and the median. Likewise the 1 sigma (error) is the difference between the median and the lower 1 sigma quantile. Data Set S5. ds05.xlsx Median timescales and 1 sigma errors from the plagioclase crystals of this study. Results from each of the parameterisations of the Mginplagioclase diffusion data are included: Faak et al, (2013), Van Orman et al., (2014) and a combined expression. Data Set S6. ds06.xlsx Spreadsheet containing the regression parameters and covariance matrices used in this study and in Mutch et al. (2019). Additional versions of the olivine regressions where the ln fO2 is expressed in Pa have been made for completeness. We recommend using the versions where ln fO2 is expressed in its native form (bars).

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. Wholerock data taken by Xray 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, carderaforming eruption that caused approximately 36,000 fatalities. It is also the only eruption of its size to have accompanying written accounts.