Fe-oxide deposits of the Lahn-Dill-type in the eastern Rhenish Massif comprise haematite and quartz with minor siderite, magnetite, and calcite. The deposits are located in the hanging wall of thick volcaniclastic rock sequences and mark the Middle to Late Devonian boundary. Varying ore types with accompanying footwall rocks were sampled from two formerly important ore deposits, the Fortuna mine (Lahn syncline) and the Briloner Eisenberg mine (East Sauerland anticline), in order to elucidate the interplay of processes leading to ore formation. Deposit geology, petrography, and whole-rock geochemistry suggest that the ores formed by iron mobilisation from deeply altered footwall volcaniclastic rocks, subsequent venting of a modified H₂O-CO₂-Fe-rich and H₂S-poor fluid, and precipitation on the seafloor (sedimentary-type), or locally by metasomatic replacement of wall rocks (replacement-type). Petrographic analysis to the sub-micron scale revealed that the sedimentary-type ores most likely formed from a Fe-Si-rich gel and accompanying maturation. Early gel textures include the presence of spherules, aggregates, tubes, and filamentous stalks consisting of nanocrystalline haematite dispersed in a matrix of microcrystalline quartz. Local diagenetic Fe³⁺ reduction within the gel is indicated by siderite replacement of haematite. Replacement-type ores formed due to a two-step process including coprecipitation of (precursor) haematite and carbonates and subsequent metasomatic replacement by haematite. These ore-forming processes took place during a time when several restricted shallow marine basins in the north-eastern Rheic Ocean were influenced by extensive volcanism and associated hydrothermal fluid flux. Examples of similar volcanic-associated Fe-oxide occurrences of Silurian to Carboniferous age can be categorised as being of Lahn-Dill-type ores as well.

莱茵地块东部的拉恩-迪尔型铁氧化物矿床由赤铁矿和石英组成，并含有少量菱铁矿、磁铁矿和方解石。这些沉积物位于厚火山碎屑岩序列的上盘中，标志着中泥盆世到晚泥盆世的边界。从福尔图纳矿（拉恩向斜）和 Briloner Eisenberg 矿（东绍尔兰背斜）这两个以前重要的矿床中对不同矿石类型及其下盘岩石进行了采样，以阐明导致矿石形成的过程的相互作用。_{矿床地质学、岩相学和全岩地球化学表明，矿石是由深度蚀变的下盘火山碎屑岩中的铁动员、随后富含 H 2} O-CO ₂ -Fe 和 H ₂ S的改性流体的喷发以及沉淀形成的。在海底（沉积型），或在局部通过围岩的交代置换（置换型）。亚微米尺度的岩相分析表明，沉积型矿石很可能是由富含 Fe-Si 的凝胶和伴随的成熟过程形成的。早期的凝胶结构包括由分散在微晶石英基质中的纳米晶赤铁矿组成的球粒、聚集体、管和丝状茎的存在。赤铁矿的菱铁矿替代表明凝胶内局部成岩作用 Fe ^3+还原。置换型矿石是通过两步过程形成的，包括（前体）赤铁矿和碳酸盐的共沉淀以及随后被赤铁矿的交代置换。这些成矿过程发生在瑞克洋东北部几个有限的浅海盆地受到广泛的火山活动和相关热液流体通量影响的时期。志留纪至石炭纪时期与火山相关的铁氧化物矿点的类似实例也可归类为 Lahn-Dill 型矿石。