“铁岩(ironstone)”在这里是指含铁超过15％的化学沉积岩;“铁建造(iron formation)”是指主要由铁岩组成的可填图的岩石单元,而且其最上层和最下层都是铁岩。化学沉积岩的定义是,占体积百分之五十以上的是从表层水体中析出的无机和(或)有机化学沉淀物及(或)其成岩交代 “Ironstone” here refers to more than 15% of chemical sedimentary rocks containing iron; “iron formation” refers to graphitally-filled rock units composed mainly of iron rocks, and the uppermost and lowermost layers Are iron rock. Chemical sedimentary rock is defined as more than fifty percent of the volume of inorganic and / or organic chemical precipitates and / or diagenetic metasogens that have precipitated from surface waters