Types and general characteristics of the BIF-related iron deposits in China

Abstract

BIFs (banded iron formations) in China, which account for approximately 64% of the total identified resources in the country, belong to two categories: a predominant Neoarchean Algoma-type and a few Paleoproterozoic Superior-type. A minor group of BIFs developed in the Neoproterozoic is also representing, having possible correlation with the “Snowball Earth” scenario. Spatially, the BIFs in China are mainly distributed in the North China Craton. They experienced intense metamorphism and deformation, which led to the majority of iron oxides changing into coarse-grained magnetites. Though their ores generally contain only 30% TFe, the BIFs are potential targets of industrial exploitation by magnetic beneficiation. On the basis of ore-forming age, host formations, mineral assemblages, and grade of the ores, the BIF-related iron deposits in China are classified into seven types. (1) Anshan-type: Neoarchean volcanic sedimentary formations with magnetite as the main ore mineral (20%≤TFe<50%); this group belongs to the Algoma-type, and is represented by the Waitoushan iron deposit in Liaoning province. (2) Yuanjiacun-type: Paleoproterozoic clastic sedimentary formation with magnetite, martite and some siderite (20%≤TFe<50%) as the major ore minerals; this group belongs to the Superior-type, and is represented by the Yuanjiacun iron deposit in Shanxi province. (3) Dalizi-type: Paleoproterozoic clasolite–carbonate formation, with magnetite, hematite and siderite as the useful minerals (20%≤TFe<50%); this group belongs to the Superior-type, and is represented by the Dalizi iron deposit in Jilin province. (4) Jingtieshan-type: Mesoproterozoic BIFs with hematite and specularite as the ore minerals (20%≤TFe<50%); this group belongs to Superior-type, and is represented by the Jingtieshan iron deposit in Gansu province. (5) Xinyu-type: Neoproterozoic banded iron formations (BIFs) with magnetite as the dominant ore mineral (20%≤TFe<50%); this group belongs to the Rapitan-type, and is represented by the Yangjiaqiao iron deposit in Jiangxi province. (6) Gongchangling-type: high-grade iron deposits developed from the Anshan-type iron deposits by late hydrothermal superimposition and reformation. The ores are mainly composed of magnetite, with TFe grade higher than 50%, and represented by mining area II of Gongchangling iron deposit in Liaoning province. (7) Shilu-type: Neoproterozoic high-grade iron deposit, mainly hematite, with TFe grade greater than 50%, represented by the Shilu iron deposit in Hainan province.