Petrological and geochemical features of the Jingtieshan banded iron formation (BIF): A unique type of BIF from the Northern Qilian Orogenic Belt, NW China

Origin of the Mesoproterozoic Jingtieshan bedded barite deposit, North Qilian Mountains, NW China: Geochemical and isotope (O, S, Sr) evidence

“…Barite is the most common mineral in the orebodies (>80%), followed by carbonate minerals (siderite and dolomite; Figure c,e), and specularite (Figure f). Hence, the mineral assemblage is similar to that of the BIF (X. Q. Yang et al, ).…”

“…The contacts between the barite orebodies and BIF are gradational, and both are concordant with the other sedimentary units in the group. The Jingtieshan BIF comprises oxide, carbonate, and mixed carbonate–oxide facies rocks, which are composed of specularite (hematite), quartz, carbonate minerals (siderite, ankerite, dolomite), magnetite, barite, chlorite, albite, tourmaline, sericite, and pyrite (X. Q. Yang et al, ). The BIF displays banded and lamellar structures (Figure a), with secondary massive, phyllitic, and brecciated structures.…”

“…The Jingtieshan deposit contains 557 million tons of proven iron ore resources with an average total Fe grade of 40%. It also contains >0.2 million tons of copper reserves with an average grade of 1.82% Cu, and 20 million tons of barite with an average grade of 8.0% BaSO 4 (H. M. Li et al, ; Mao et al, ; H. Z. Yang et al, ; X. Q. Yang, Zhang, Duan, & Zhao, ). However, the bedded barite deposit, which overlies and was interlayered with the BIF, remains unexploited.…”

“…However, the bedded barite deposit, which overlies and was interlayered with the BIF, remains unexploited. Previous studies have shown that the Jingtieshan BIF consists of alternating Fe‐rich (specularite/hematite and siderite), silica‐rich, and barite‐rich layers, containing high Fe 2 O 3 t , SiO 2 , and BaO contents (H. M. Li et al, ; Mao et al, ; Xue et al, ; H. Z. Yang et al, ; X. Q. Yang et al, ; Zhou & Yue, ). Although it is understood that the BIF precipitated from submarine hydrothermal solutions showing a weak seawater signature (X. Q. Yang et al, ).…”

“…Previous studies have shown that the Jingtieshan BIF consists of alternating Fe‐rich (specularite/hematite and siderite), silica‐rich, and barite‐rich layers, containing high Fe 2 O 3 t , SiO 2 , and BaO contents (H. M. Li et al, ; Mao et al, ; Xue et al, ; H. Z. Yang et al, ; X. Q. Yang et al, ; Zhou & Yue, ). Although it is understood that the BIF precipitated from submarine hydrothermal solutions showing a weak seawater signature (X. Q. Yang et al, ). Most researchers have argued that Cu mineralization at Huashugou mine of the Jingtieshan deposit has an epigenetic hydrothermal origin (e.g., Mao et al, ; X. Q. Yang et al, ; L. Y. Zhang, Qu, & Xin, ).…”