Stanniferous magnetite composition from the Haobugao skarn Fe–Zn deposit, southern Great Xing'an Range: Implication for mineral depositional mechanism

Abstract

The Great Xing'an Range in north‐eastern China hosts numerous super‐large Ag–Pb–Zn deposits and some Fe–Sn deposits. The Mesozoic Haobugao Fe–Zn polymetallic skarn deposit in the southern Great Xing'an Range is contemporaneous with the regional Ag–Pb–Zn mineralization. Numerous ore bodies are hosted in the Lower Permian carbonate strata or along the contact with the Early Cretaceous granite. According to the field and systematic petrography and mineralography research, the Haobugao mineralization phases are divided into 3 paragenetic stages: prograde stage, retrograde stage, and sulphide stage. Magnetite mainly occurred in the retrograde stage and replaced the anhydrous skarn minerals (e.g., garnet and diopside). Two types of magnetite (Mag1 and Mag2), including 6 subtypes, can be distinguished based on the scanning electron microscopy and back scattered electron images. Electron probe microanalysis and laser ablation inductively coupled plasma mass spectrometer analysis were used to determine major and trace elements in different types of magnetite. Mag1 has higher Ti and V concentrations than Mag2, indicating a relatively higher depositional temperature. Mag1 also contains relatively higher Mg and Mn concentrations, coupled with much lower Si and Al concentrations, which reflects a low fluid/rock ratio at the site of Mag1 deposition. Element variation features of Mag1 and Mag2 reveal that the Haobugao mineralization fluids gradually evolved from high‐temperature and low fluid/rock ratio fluids to relatively low‐temperature and high fluid/rock ratio fluids. However, electron probe microanalysis data of Mag2 display significantly higher Sn concentrations (up to 2.82 wt.%) than that in Mag1, which indicates that Sn can be incorporated into magnetite crystal lattice. We propose a possible substitution mechanism of Sn4+ + Mn2+ = 2Fe3+, supported by the strongly positive correlation between Sn4+ and Mn2+, whereby a substitution of Sn4+ for Fe3+ in octahedral sites of magnetite requires a compensatory substitution of Mn2+ for Fe3+ to maintain the charge balance.

Textural, chemical, isotopic and microthermometric features of sphalerite from the Wunuer deposit, Inner Mongolia: Implications for two stages of mineralization from hydrothermal to epithermal

“…The Wunuer Pb–Zn–Ag–Mo deposit is located in the middle segment of the Great Xing'an Range, Inner Mongolia, NE China (Figure 1a). The Great Xing'an Range zone belongs to the eastern segment of the Central Asian Orogenic Belt, where contains a major Late Jurassic‐ to Early Cretaceous‐aged (150–120 Ma) magmatic and volcanic rocks (Wu, Li, Yang, & Zheng, 2007) as well as plenty of associated skarn‐, porphyry‐, magmatic hydrothermal‐ and epithermal‐type ore deposits (Wang, Wei, Lv, Fan, & Wang, 2017; Zeng, Liu, Yu, Ye, & Liu, 2011). Particularly, in the middle segment of the Great Xing'an Range zone distributed many Late Jurassic‐ to Early Cretaceous‐aged granite‐related porphyry–hydrothermal–epithermal composite Ag–Mo–Cu–Pb–Zn polymetallic ore deposits (Jing et al, 2014; Li et al, 2014; Liu et al, 2013; Zhai et al, 2009).…”

“…(a) Tectonic setting of NE China (modified from Wang et al, 2017). (b) Regional geological map of the Wunuer deposit [Colour figure can be viewed at wileyonlinelibrary.com]…”

Geological, Geochemical, and Mineralogical Constraints on the Genesis of the Polymetallic Pb-Zn-Rich Nuocang Skarn Deposit, Western Gangdese, Tibet

“…In comparison to the proximal Fe-Cu skarn, the Pb-Zn skarn are formed at relatively long distances from the causative magmatic rocks, thus forming in a lower temperature environment [1][2][3][4]. The infiltrative skarn deposits show affinity with magmatic hydrothermal activity, and their compositions positively correlate with that of the generating magmatic rocks [1,5]. They are characterized by the overall zonation that is based on the mineral assemblages in space, from the causative plutons through the proximal skarn zone towards the distal skarn zone, then the wall-rocks.…”

Genesis of the Huangshaping W–Mo–Cu–Pb–Zn deposit, South China: Role of magmatic water, metasomatized fluids, and basinal brines during intra‐continental extension

“…Lithospheric extension and subcrustal lithospheric thinning may be key drivers of hot, metal‐rich basinal brine migration, responsible for the formation of large‐scale Pb–Zn polymetallic ore deposits (Betts & Lister, ), Mississippi Valley‐type deposits (MVT; Hanilçi & Öztürk, ), and Pb, Zn, Ag, Au, and/or barite sedimentary exhalative (Sedex) deposits (Diehl et al, ; Li & Xi, , ). However, the origin of fluids and the degree of interaction between basinal brines, magmatic‐metasomatized fluid, and meteoric water in a magmatic‐hydrothermal polymetallic mineralization system, generated during intra‐continental extension, are still unclear (Essarraj et al, ; Hofstra et al, ; Li, Watanabe, Xi, & Yonezu, ; Li, Xi, Wu, & Watanabe, ; Rddad & Bouhlel, ; Sun, Li, Danišík, et al, ; Sun, Li, Evans, et al, ; Wang, Yang, et al, ; Wang, Wei, et al, ).…”

“…However, the origin of fluids and the degree of interaction between basinal brines, magmatic-metasomatized fluid, and meteoric water in a magmatic-hydrothermal polymetallic mineralization system, generated during intra-continental extension, are still unclear (Essarraj et al, 2016;Hofstra et al, 2016;Li, Watanabe, Xi, & Yonezu, 2013;Li, Xi, Wu, & Watanabe, 2013;Rddad & Bouhlel, 2016;Sun, Li, Danišík, et al, 2017;Sun, Li, Evans, et al, 2017;Wang, Yang, et al, 2017;Wang, Wei, et al, 2017).…”