This study utilized X-ray micro-computed tomography (micro-CT) to investigate weathered gypsum rocks which can or do serve as a rock substrate for endolithic organisms, focusing on their internal pore-fracture microstructure, estimating porosity, and quantitative comparison between various samples. Examining sections and reconstructed 3D models provides a more detailed insight into the overall structural conditions within rock fragments and the interconnectivity in pore networks, surpassing the limitations of analyzing individual 2D images. Results revealed diverse gypsum forms, cavities, fractures, and secondary features influenced by weathering. Using deep learning segmentation based on the U-Net models within the Dragonfly software enabled to identify and visualize the porous systems and determinate void space which was used to calculate porosity. This approach allowed to describe what type of microstructures and cavities is responsible for the porous spaces in different gypsum samples. A set of quantitative analysis of the detected void and modeled networks provided a needed information about the development of the pore system, connectivity, and pore size distribution. Comparison with mercury intrusion porosimetry showed that both methods consider different populations of pores. In our case, micro-CT typically detects larger pores (> 10 μm) which is related to the effective resolution of the scanned images. Still, micro-CT demonstrated to be an efficient tool in examining the internal microstructures of weathered gypsum rocks, with promising implications particularly in geobiology and microbiology for the characterization of lithic habitats.

中文翻译：

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利用显微 CT 评价石膏岩石碎片的孔隙-裂隙微观结构

本研究利用 X 射线微计算机断层扫描 (micro-CT) 来研究风化石膏岩石，这些岩石可以或确实作为内石生物的岩石基质，重点研究其内部孔隙-裂缝微观结构，估计孔隙度，并对不同岩石之间的定量比较样品。检查剖面和重建的 3D 模型可以更详细地了解岩石碎片内的整体结构状况和孔隙网络的互连性，超越了分析单个 2D 图像的局限性。结果揭示了受风化影响的不同石膏形态、空腔、裂缝和次要特征。使用 Dragonfly 软件中基于 U-Net 模型的深度学习分割，能够识别和可视化多孔系统，并确定用于计算孔隙率的空隙空间。这种方法可以描述不同石膏样品中多孔空间的微观结构和空腔类型。对检测到的空隙和建模网络进行的一组定量分析提供了有关孔隙系统发展、连通性和孔径分布的所需信息。与压汞孔隙率测定法的比较表明，两种方法都考虑了不同的孔隙群。在我们的例子中，微型 CT 通常检测较大的孔隙（> 10 μm），这与扫描图像的有效分辨率有关。尽管如此，微型 CT 仍被证明是检查风化石膏岩石内部微观结构的有效工具，特别是在地球生物学和微生物学中，对于表征石器生境具有广阔的前景。