X-ray computed tomography (CT) is a non-destructive imaging technique that provides three-dimensional (3D) visualisation and high-resolution quantitative data in the form of CT numbers. CT numbers are derived from the X-ray energy, effective atomic number and density of the analysed material. The sensitivity of the CT number to changes in material density means that it can be used to identify facies changes within sediment cores by detecting downcore shifts in sediment properties, and to quantify skeletal linear extension rates and internal biological erosion from coral cores. Here we present two algorithms to analyse CT scan images for geoscience research and package them within an open-source MATLAB application (Core-CT) that is freely available at GitHub (https://github.com/yuting-yan/Core-CT). The first algorithm computes CT numbers from a user-defined region of interest to identify boundaries of density change (e.g., sedimentary facies, laminations, coral growth bands). The second algorithm segments regions with major density contrast (e.g., internal void space or biogenic material) and provides 3D geometrical measurements of these irregularities. The versatility of Core-CT for geoscience is demonstrated for a range of environmental settings using both lake and marine sediment cores (Chile and Singapore) and coral cores (Red Sea). Core-CT analysis of sediment cores shows the application is able to: (1) distinguish episodic tsunami deposits from lacustrine sediments, (2) generate rapid and detailed measurement of varved sediments, and (3) identify sedimentary facies from an unsplit marine sediment core. When applied to coral cores, Core-CT can measure skeletal linear extension of annual growth bands and provide 3D visualisation and volumetric quantification of internal bioerosion cavities. Other potential applications of Core-CT include the identification of cryptotephra in sediment cores, or laminations in speleothem samples.

X 射线计算机断层扫描 (CT) 是一种无损成像技术，它以 CT 数字的形式提供三维 (3D) 可视化和高分辨率定量数据。CT 值源自所分析材料的 X 射线能量、有效原子序数和密度。CT 数对材料密度变化的敏感性意味着它可用于通过检测沉积物性质的下芯变化来识别沉积物核心内的相变化，并量化珊瑚核心的骨骼线性延伸率和内部生物侵蚀。在这里，我们提出了两种算法来分析用于地球科学研究的 CT 扫描图像，并将它们打包在开源 MATLAB 应用程序 (Core-CT) 中，该应用程序可在 GitHub (https://github.com/yuting-yan/Core-CT) 上免费获得）。第一种算法从用户定义的感兴趣区域计算 CT 数，以确定密度变化的边界（例如，沉积相、层理、珊瑚生长带）。第二个算法分割具有主要密度对比度的区域（例如，内部空隙空间或生物材料）并提供这些不规则性的 3D 几何测量。Core-CT 用于地球科学的多功能性在使用湖泊和海洋沉积物核心（智利和新加坡）以及珊瑚核心（红海）的一系列环境设置中得到了证明。沉积物岩心的岩心 CT 分析表明，该应用程序能够：(1) 区分偶发性海啸沉积物和湖相沉积物，(2) 生成对变质沉积物的快速和详细测量，以及 (3) 从未分裂的海洋沉积物岩心中识别沉积相. 当应用于珊瑚核时，Core-CT 可以测量年生长带的骨骼线性扩展，并提供内部生物侵蚀腔的 3D 可视化和体积量化。Core-CT 的其他潜在应用包括识别沉积物核心中的隐藻，或洞穴样品中的叠层。