X-ray µ-CT data reconstruction, image stack of ICPD Core ICDP5059_1_C

This contribution comprises true-3D volume datasets ("Digital drill cores"), acquired by a X-ray Computed Microtomography (μ-CT) survey on reference drill core material recovered from Hole 5059-1-C (192 m) on Surtsey volcano (Vestmannaeyjar archipelago, Iceland), drilled by the SUSTAIN drilling project (Surtsey Underwater volcanic System for Thermophiles, Alteration processes and INnovative Concretes, see Jackson et al. 2019 for details). Seventeen reference samples (see Weisenberger et al. 2019 for preparational details) (ranging from 22.66 to 180.65 m vertical depth, sampling roughly every 10 m) were scanned as quarter cores. The X-ray μ-CT scans were performed using the ProCon CT-ALPHA system of the Petrology of the Ocean Crust research group at the University of Bremen, Germany. This μ-CT survey has been conducted as part of the DFG SPP 1006 grant "Rates and Processes of Tephra Alteration on Surtsey: Observations and Experiments". In order to avoid imaging of void space due to the quarter core shape, and to achieve a higher magnification, the scans were performed as "out-of-area"-scans (see, e. g. Kahl et al., 2016), restricting observations to the inner regions of the samples. The reconstructed image material is of cylindrical shape with a resolution of ca. 7.5 μm/voxel, and represents virtual drill cores of ca. 15 mm diameter and 15 mm height. The μ-CT-derived image volumes comprise the true 3-D spatial arrangement of fabric compounds in the rock. In the reconstructed 16-bit greyscale volume data, areas of highly attenuating phases (e.g. magnetite, olivine) are encoded in light grey values, whereas areas of low X-ray absorption are color-coded in dark grey (e.g. clays) or black (e.g. voids, cracks). In order to facilitate straightforward access to the digital drill core image material, the volume data is provided as a zipped stack of tif images. In addition, each digital drill core is characterized by three types of visualization: (i) shaded and classical texture-based volume rendering (volren), (ii) maximum intensity projection (volren-MIP): visualization of the highest intensity in a data volume along the current line of sight, and (iii) three perpendicular virtual cutting planes (3-slices). As an added value to the non-destructive visualization procedure, the reconstructed X-ray micro-CT scans of the studied reference drill core material provide volume reconstructions which can serve as digitypes that may be studied as digital facsimile without the necessity of consulting / modifying / destructive interactions of the actual type specimens (e. g. by physical permeability tests). These image data can be used for quantitative 3D image analysis, e. g. to derive empirical relations between porosity, the extent of replacement of primary phases, and the distribution of secondary phases (and many more).本数据集包含真实三维体数据集——“数字岩心（Digital drill cores）”，其由SUSTAIN钻探项目（全称：叙尔特塞水下火山系统嗜热微生物、蚀变过程与创新混凝土研究项目，详见Jackson等2019年研究）在冰岛韦斯特曼纳埃亚尔群岛叙尔特塞火山钻取的5059-1-C号钻孔（总深度192米）中获取的参考岩心样品，经X射线计算机显微断层扫描（X-ray Computed Microtomography，μ-CT）采集得到。 本次共扫描了17个参考样品（样品制备细节详见Weisenberger等2019年研究），样品垂向深度范围为22.66至180.65米，采样间距约10米，扫描形式为四分岩心。本次X射线μ-CT扫描由德国不来梅大学洋壳岩石学研究组采用ProCon CT-ALPHA系统完成。本次μ-CT扫描是德国研究基金会（DFG）SPP 1006项目“叙尔特塞火山火山灰蚀变速率与过程：观测与实验”的研究内容之一。为避免因四分岩心形状导致空隙成像，并获得更高的放大倍率，本次扫描采用“区域外扫描”模式（详见Kahl等2016年研究），仅对样品内部区域进行观测。重构后的图像数据呈圆柱形，分辨率约为7.5微米/体素（voxel），对应直径约15毫米、高度约15毫米的虚拟岩心。 由μ-CT得到的图像体数据完整呈现了岩石中组构组分的真实三维空间分布。在重构的16位灰度体数据中，高衰减相（如磁铁矿、橄榄石）以浅灰值编码，而X射线吸收较弱的区域则以深灰（如黏土）或黑色（如空隙、裂缝）进行颜色编码。为便于直接获取数字岩心图像数据，体数据以压缩的标签图像文件格式（Tagged Image File Format，TIFF）图像栈形式提供。此外，每个数字岩心均提供三类可视化结果：(i) 带阴影的经典纹理体绘制（volren）；(ii) 最大密度投影（volren-MIP）：沿当前视线方向对数据体中最高强度值进行可视化；(iii) 三个正交虚拟切割平面（3-slices）。 作为无损可视化流程的附加价值，本次针对参考岩心样品开展的X射线显微CT扫描重构数据可作为“数字标本（digitypes）”，可作为实体标本的数字复制品开展研究，无需对实体模式标本进行查阅、修改或破坏性操作（例如物理渗透性测试）。该图像数据可用于定量三维图像分析，例如推导孔隙度、原生矿物被置换程度与次生矿物分布之间的经验关系（以及更多研究方向）。