Ferruginous deposits are iron-rich sediments or sedimentary rocks found in various sizes, shapes, and compositions within sedimentary strata in different depositional settings. This study investigates the characteristics, distribution, and origin of ferruginous deposits found in the Late Ordovician glaciogenic Sarah Formation and surrounding deposits in central Saudi Arabia. Several types of ferruginous deposits have been identified through field observations and laboratory investigations, including thin-section petrography, geochemical, surface, and bulk mineralogical analyses, and computed tomography scans. The identified ferruginous deposits include solid and rinded concretions, pipes, layers, ferricretes, liesegang bands, and fracture infills. They were associated with the periglacial and proglacial facies of the Sarah Formation. For instance, ferruginous deformed layers were mainly observed in subglacial facies, while rinded concretions occurred in bleached glaciofluvial facies. Ferruginous deposits were also found in the uppermost parts of non-glacial facies, such as the shallow marine Quwarah Member of the Qasim Formation and the braided deltaic Sajir Member of the Saq Formation. Compositionally, goethite was the dominant iron oxide mineral in all ferruginous deposits, and it is mostly distributed as cement, filling pore spaces. In comparison to ferruginous deposits reported in different depositional settings on Earth and Mars, the studied ferruginous deposits in an ancient glaciogenic setting exhibit different mineralogical characteristics. Specifically, the studied solid concretions are less abundant and primarily amalgamated, while the rinded concretions appear to be more mature than those reported in other depositional environments. This study suggests that the weathered basement rocks of the Arabian Shield were the primary source of iron. The iron-bearing rocks were eroded and transported by Hirnantian glaciation and deglaciation processes.

含铁矿床是在不同沉积环境的沉积地层中发现的各种尺寸、形状和成分的富铁沉积物或沉积岩。本研究调查了沙特阿拉伯中部晚奥陶世冰川形成萨拉组及其周围矿床中发现的含铁矿床的特征、分布和来源。通过现场观察和实验室调查，包括薄片岩相学、地球化学、表面和整体矿物学分析以及计算机断层扫描，已经确定了几种类型的铁质矿床。已发现的含铁矿床包括固体和带皮结核、管道、地层、铁混凝土、列塞刚带和裂缝填充物。它们与萨拉组的冰缘相和冰前相有关。例如，铁质变形层主要出现在冰下相中，而剥皮结核则出现在白化的冰河相中。非冰川相最上部也发现了铁质矿床，如浅海相的卡西姆组 Quwarah 段和辫状三角洲 Saq 组的 Sajir 段。从成分上看，针铁矿是所有含铁矿床中主要的氧化铁矿物，并且大部分以胶结物形式分布，填充孔隙空间。与地球和火星上不同沉积环境中报告的铁质矿床相比，所研究的古代冰川形成环境中的铁质矿床表现出不同的矿物学特征。具体来说，所研究的固体结核数量较少，并且主要是合并的，而剥皮结核似乎比其他沉积环境中报道的更为成熟。这项研究表明，阿拉伯地盾的风化基底岩石是铁的主要来源。含铁岩石受到赫南蒂安冰川作用和冰消蚀过程的侵蚀和搬运。