Dissolution experiment using a mid-ocean ridge basalt exposed to CO2-enriched water.

Author - Lange, IsabelProject - AIMS3-Alternate scenarios, Innovative technologies, and Monitoring approaches for Sub-Seabed Storage of carbon dioxide, CDRmare, Research Mission of the German Marine Research Alliance (DAM) "Marine carbon sinks in decarbonisation pathways" General=======This data publication is supplementary to the publication by Lange I., Plümper O., King H. E., Hansen C. T., Lüttge A., Ostertag-Henning C., Toro M., Bach W., "Grain by grain: spatially resolved dissolution rates of intact mid-ocean ridge basalt exposed to CO2-enriched water." Materials and Methods=====================Experiment:This data set provides the results of a laboratory flow-through dissolution experiment using a mid-ocean ridge basalt exposed to ultra-pure water enriched in carbon dioxide (287 mmol/kgw) for 42 days. The experimental temperature was 70°C and the calculated (phreeqC, Parkhurst and Appelo, 2013) in-situ pH was 3.4. Bulk rock and mineral composition (XRF, EPMA):Bulk rock composition was determined by X-ray fluorescence (XRF) analysis using a Panalytical Axios Plus Instrument at the University of Oldenburg. A thin section was prepared (Dettmar dissection Technology GmBH & Co. KG) for mineral analysis by electron probe microanalysis (EPMA). Surface topography (VSI):Surface reactivity was analyzed based on surface topography measurements before (polished surface) and after the experiment using a Bruker Contour GT-I vertical scanning interferometry (VSI), Department of Geosciences, University of Bremen. A part of the surface was covered during the experiment and remained unreacted. This area served as reference height to calculate absolute changes in surface height (surface retreat) by subtracting the topography maps (Subtraction Maps). Dissolution rate maps were obtained by dividing the height change by the experimental duration and the molar volume of the material/individual phase. Phase segmentation and statistics (Raman, VSI):A subarea of the maps was used to calculate the surface retreat and dissolution rates for four major and minor phases of the basalt: plagioclase, clinopyroxene, interstitial glass, and titanomagnetite, identified using Raman spectroscopy (Renishaw inVia Raman spectrometer, Department of Geosciences, University of Bremen). The VSI light reflection images (grayscale images) were used to segment the data for each phase and apply the segments to the height and dissolution rate maps. The segmented maps were used to calculate statistics. Intra-/intercrystalline analysis (SEM, EPMA-VSI cross-referencing): The two major phases, plagioclase and pyroxene, were analyzed for inter- and intracrystalline variabilities in reactivity and chemical composition. Backscatter electron (BSE) and secondary electron (SE) images were obtained using a field emission scanning electron microscopy (FE-SEM, SUPRA 40, Zeiss, Department of Geosciences, University of Bremen). Correlation of surface reactivity and chemical composition was done by performing simple point and line profile measurements using a Cameca SX100 electron probe microanalysis (EPMA), Department of Geosciences, University of Bremen, and extract VSI data at the same measurement spots from the maps. Since the lateral Resolution of the VSI Maps (140 nm) is higher than the measurement spot of a EPMA measurement, the VSI data were averaged over 2x2 micrometer. Software used=============WiRE® (Renishaw plc) version 5.6Digital Surf, MountainsLab® version 11SPIP (Image Metrology A/S) version 6.7.4MATLAB R2023aPython version 3.1.3 Folder Structure================The data is organized based on the different analyses and is seperated into 8 folders with subfolders. Folder Contents===============List and content of folders with subfolders (latter ones are indicated by "-"). Images used for Figures are in the respective "Visualizations" folders, the respective data are in the "Data" folders. EPMA:- Data: EPMA measurements performed on the basalt sample and thin sections for plagioclase, pyroxene, magnetite, interstitial glass, glassy rim, and reference standard materials - Visulaizations: images of the measurement spots on the basalt sample (from the stiched image and the zoned plagioclase crystals) Experiment: - Visualizations: images of the sample, the reactor, and the flow-through system (used for Figure 1, Figure S1) Literature: - Visualizations: images comparing the results with literature data (used for Figure 8, Figure S11) Raman: - RAW: representative spectra for plagioclase, pyroxene, and intersitial glass - PROCESSED: - Data: processed spectra for plagioclase, pyroxene, and intersitial glass (truncated, baseline subtracted, noise filtered, normalized) - Visualizations: image of the processed spectra for plagioclase, pyroxene, and intersitial glass (used for Figure S4) SEM: - Visualizations: image files (BSE and SE) of reacted areas of the sample surface (used for Figure 3) XRF-EPMA: - Data: XRF and EPMA values to calculate mineral abundances and bulk dissolution rate VSI-EPMA:- Plagioclase: - Data: 2x2 micrometer maps (for point measurements), line profiles extracted from the VSI plagioclase rate map, and all data collected in one file to correlate with EPMA measurements. - Visualizations: images of selected grains used for VSI-EPMA correlation with color scales, representative plots of three VSI-EPMA line profiles, and a plot showing the anorthite content versus the dissolution rates of the selected grains (used for Figure 5, Figure S5) - Pyroxene: - Data: 2x2 micrometer maps (for point measurements), line profiles extracted from the VSI pyroxene rate map, and all data collected in one file to correlate with EPMA measurements. - Visualizations: images of selected grains used for VSI-EPMA correlation with color scales, representative plots of three VSI-EPMA line profiles, and several plots showing pyroxene composition with respective measured dissolution rates (used for Figure 6, Figure 7, Figure S2, Figure S6, Figure S7, Figure S8, Figure S9, and Figure S10) VSI:-RAW: - stitched_ area: topography and grayscale images before (t0) and after (t1) the experiment - zoned_plagioclase_crystals - PROCESSED: - distance_rim: - Data: VSI maps and respective pixels (_cleaned_values) used to calculate statistics for surface retreat with increasing distance from the rim of the flow channel - Visualizations: Box-and-whisker plot of the surface retreat (sections 1-4) with increasing distance from the rim of the flow channel (used for Figure S3) - error_calculation: - Data: Subtraction map of the masked area (t0-t1) used to calculate the minimum measurement error - stitch: - Data: Topography maps (t0 and t1), extracted height profiles (t0 and t1), Subtraction Map, and Rate Maps for plagioclase and pyroxene. Note: the rate maps give only the right values for the respective phase in the maps, which can be identified with help of the grayscale images. - Visualizations: image files for the topography maps (t0 and t1), the extracted height profiles (t0 and t1), the Subtraction Map, and the respective color scales (used for Figure 2) - subarea_statistical_analysis: - Data: Subtraction and rate maps for the entire subarea and the four phases (plagioclase, pyroxene, magnetite, and glass), the extracted pixels for each map (_cleaned_values) to calculate statistics, and the results of the calculations - Visualizations: Images of the grayscale (t0 and t1), the subtraction map of the subarea, and histogram and box-and-whisker plots for the subtraction and rate maps (used for Figure3, Figure 4) - zoned_plagioclase_crystals: - Data: Subtraction and rate maps of the zoned plagioclase crystals - Visualizations: images of the rate maps and the color scale (used for Figure 5) Important notes on VSI files=============================The *.asc files of the processed VSI maps contain two matrices. One that gives a height value per pixel and one below that only contains binary values to indicate which pixel values are true (0) and false (1) after the respective processing (e.g., excluding data in pores, for phase segmentation, etc.). Therefore, for the statistical calculations, additional files with the extracted true values (_cleaned_values) are given. The x- and y- coordinates are given in nm for all VSI maps. Formats=======All image files are provided as *.tiff or *.png files.All data files are provided as *.txt, *.asc, or *.csv files. Abbreviations=============An = anorthite fractionAb = albite fractionBSE = backscattered electronEn = enstatite fractionEPMA = electron probe microanalysisFig = figureFs = ferrosilite fractionMag = magnetiteMg# = magnesium numberMM = molar massOr = orthoclase fractionPlag = plagioclasePyrox = pyroxene SE = secondary electronSEM = Scanning electron microscopeVSI = vertical scanning interferometryWo = wollastonite fractionXRF = X-rax fluorescence References=========Parkhurst, D.; Appelo, C. A. J. Description of input and examples for PHREEQC version 3: A computer program for speciation, batch-reaction, one-dimensional transport, and inverse geochemical calculations; Reston, VA, 2013. https://pubs.usgs.gov/publication/tm6A43DOI: 10.3133/tm6A43.