The North and South Flank deposits are located on the flanks of the Weeli Wolli anticline at Mining Area C in the central Hamersley Province. Supergene martite-goethite mineralization is hosted within the Marra Mamba Iron Formation and is developed over a strike length of more than 60 km. This multibillion metric ton resource has been drilled out on a 150- × 50- to 50- × 50-m grid, thus providing us with an unprecedented data set for analysis. This study synthesizes the drill hole data and presents a physical process model that can account for the observed distribution of mineralization.A fluid and mass flux model is proposed which envisages a three-stage process: (1) leaching of Fe from banded iron formation (BIF) in the vadose zone by reduced, acidic, meteoric-derived fluids; (2) penetration of an Fe-rich supergene-fluid plume, driven by gravity and focused by bedding-parallel permeability into the body of ambient alkaline groundwater, effecting nonredox, mimetic replacement of magnetite by hematite and of the gangue minerals (carbonate, silicate, and chert) by goethite coupled with the release of silica into the fluid phase; and (3) a change from silica leaching to silica deposition on the downdip margins of the system before the ore-fluid plume is eventually diluted and becomes indistinguishable from the surrounding body of groundwater.Despite the undoubted secondary role played by structurally enhanced permeability, the primary control on ore-fluid hydrology is gravity-driven flow along bedding planes. This central observation explains every observed feature of the three-dimensional distribution of martite-goethite mineralization, and the inherited structural architecture simply provides the context for this process to play out. This type of control is by no means obvious–the ingress of meteoric fluids during later lateritic weathering of the mineralization does not show this control and produces broadly subhorizontal, bedding-discordant zones of overprinting.The fundamental control exerted on the distribution of martite-goethite mineralization by bedding-plane permeability within BIF horizons suggests that the supergene ore-fluid plume created its own porosity via the relevant ore-forming reactions, and that these were in turn controlled by bedding. A corollary of the pseudomorphic replacement process, both the generation of hematite after magnetite and goethite after gangue phases, is that it typically introduces porosity. The mineralizing process thus creates porosity (and potentially permeability) and is likely to be self-propagating as long as there is continuous supply of ore fluid. This putative active porosity-generation process may be an important clue as to the unique conditions of martite-goethite ore formation. Indeed, it may be that the distribution of magnetite is the critical controlling feature of these ore systems, as the nonredox transformation to hematite not only releases Fe²⁺ to the fluid phase but concurrently introduces porosity. Further research is required to formulate a comprehensive chemical (as opposed to physical) process model for supergene martite-goethite ore formation.Based on the physical process model presented here, the development of a large-scale martite-goethite mineralizing system requires continued delivery of unleached BIF (and, perhaps ultimately, previously mineralized martite-goethite ore) into the vadose zone. The Hamersley Province has been undergoing significant uplift since at least 60 Ma. Preliminary dating of martite-goethite ores from Mining Area C indicates that they formed at about 45 Ma, at a time when the local climate was temperate and wetter than today. The combination of ongoing uplift and a wet, temperate climate is likely to be the key to the widespread formation of martite-goethite deposits in the Hamersley Province.

中文翻译：

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带状铁层-马氏体-针铁矿矿化成因的新流体流模型，特别参考西澳大利亚州哈默斯利省的南北侧翼矿床

北部和南部侧翼矿床位于哈默斯利省中部C矿区Weeli Wolli背斜的侧翼。表生马氏体-针铁矿成矿作用存在于马拉曼巴铁矿层中，其走向长度超过60公里。数十亿吨的资源已在150-×50-至50-×50-m的网格上钻出，从而为我们提供了前所未有的数据集进行分析。这项研究综合了钻孔数据，并提出了可以解释矿化分布的物理过程模型。提出了一种流体和质量通量模型，该模型设想了一个三阶段过程：（1）从带状铁形成中浸出铁（ BIF）在渗流带中通过还原的，酸性的，流星来源的液体产生；（2）渗透富铁的超流体流，受重力作用驱动，并通过与地层平行的渗透性集中进入环境碱性地下水体内，从而实现非氧化还原，赤铁矿和磁铁矿的模拟替代（如针铁矿的磁铁矿矿物（碳酸盐，硅酸盐和石），以及硅石的释放）。液相 （3）在矿液羽流最终被稀释并与地下水周围体变得不可分辨之前，从系统的下倾边缘的二氧化硅浸出转变为二氧化硅沉积。尽管结构增强的渗透性无疑发挥了辅助作用，但矿石-流体水文学的主要控制是沿地层的重力驱动流。这个中心的观察解释了马氏体-针铁矿矿化的三维分布的每个观察到的特征，继承的结构体系结构只是为该过程提供了背景。这种控制方式绝不是显而易见的-在成矿作用的后期红土风化过程中，陨石的进入并没有显示出这种控制方式，而是产生了广泛的亚水平，层理不协调的叠印区域。基本控制作用在于马氏体-针铁矿的分布BIF视野内层理面渗透率的矿化作用表明，超基矿流体羽流通过相关的成矿反应产生了自己的孔隙度，而这些反过来又受层理控制。假晶置换过程的一个必然结果是，磁铁矿后生成赤铁矿和脉石阶段后生成针铁矿均会引入孔隙。因此，矿化过程会产生孔隙（并可能导致渗透性），并且只要不断供应矿液，它就有可能自我繁殖。对于马氏体-针铁矿矿石形成的独特条件，这种假定的活跃的孔隙生成过程可能是一个重要的线索。确实，磁铁矿的分布可能是这些矿石系统的关键控制特征，因为向赤铁矿的非氧化还原转变不仅会释放铁²⁺进入液相，但同时引入孔隙。尚需要进一步研究以建立一个综合的化学（相对于物理）过程模型以形成超长马氏体-针铁矿矿石。在此提出的物理过程模型的基础上，大规模马氏体-针铁矿成矿系统的开发需要持续交付将BIF（可能最终是以前矿化的马氏体-针铁矿）浸出到渗流带中。自至少60 Ma以来，哈默斯利省一直经历着明显的隆升。来自矿区C的马氏体-针铁矿矿石的初步定年表明，它们形成于大约45 Ma，此时当地气候比今天温和潮湿。持续的隆起和潮湿的结合，