3D Multi-Parameter Geological Modeling and Knowledge Findings for Mo Oxide Orebodies in the Shangfanggou Porphyry–Skarn Mo (–Fe) Deposit, Henan Province, China

Abstract

The Shangfanggou Mo–Fe deposit is a typical and giant porphyry–skarn deposit located in the East Qinling–Dabie molybdenum (Mo) polymetallic metallogenic belt in the southern margin of the North China Block. In this paper, three-dimensional (3D) multi-parameter geological modeling and microanalysis are used to discuss the mineralization and oxidation transformation process of molybdenite during the supergene stage. Meanwhile, from macro to micro, the temporal–spatial–genetic correlation and exploration constraints are also established by 3D geological modeling of industrial Mo orebodies and Mo oxide orebodies. SEM-EDS and EPMA-aided analyses indicate the oxidation products of molybdenite are dominated by tungsten–powellite at the supergene stage. Thus, a series of oxidation processes from molybdenite to tungsten–powellite are obtained after the precipitation of molybdenite; eventually, a special genetic model of the Shangfanggou high oxidation rate Mo deposit is formed. Oxygen fugacity reduction and an acid environment play an important part in the precipitation of molybdenite: (1) During the oxidation process, molybdenite is first oxidized to a MoO2·SO4 complex ion and then reacts with a carbonate solution to precipitate powethite, in which W and Mo elements can be substituted by complete isomorphism, forming a unique secondary oxide orebody dominated by tungsten–powellite. (2) Under hydrothermal action, Mo4+ can be oxidized to jordisite in the strong acid reduction environment at low temperature and room temperature during the hydrothermal mineralization stage. Ilsemannite is the oxidation product, which can be further oxidized to molybdite.

Three‐dimensional Modeling of Ore‐forming Elements and Mineralization Prognosis for the Yechangping Mo Deposit, Henan Province, China

“…1a); these faults are located on the southern margin of the North China Craton (Fig. 1b; Chen, 2000Chen, , 2009Yan et al, 2012;Ding et al, 2015;Wang G W et al, 2015;Liu et al, 2022). The Yechangping Mo deposit is situated within the EQMB and lies south of the western extension of the Machaoying fault and north of the Luanchuan fault.…”

“…The Yechangping ore district features a distinct doublecrust structure comprising a Neoarchean Taihua Group deep metamorphic rock series as the basement and the primarily the Middle Proterozoic Xiong"er Group "tridentrift" volcanic formation as the caprock (Yan et al, 2012;Liu et al, 2022).…”

“…The skarn stage is further divided into early skarn, late skarn, and oxide stages, whereas the quartzsulfide phase is separated into the early (pyroxene-sulfide) and late quartz-sulfide stages (Fig. 4; Wang Z M et al, 2013;Liu et al, 2022).…”

“…The East Qinling Mo belt (EQMB; Fig. 1b) is among the world"s most significant Mo provinces and contains approximately 6 Mt of Mo reserves (Chen et al, 2000(Chen et al, , 2009Liu et al, 2022). The Yechangping Mo deposit, a typical and substantial porphyry-skarn deposit in the EQMB, offers a large prospecting space and resource potential below a burial depth of 1000 m. However, challenges in deep exploration include high borehole costs, long lead times, limited depth and accuracy of conventional geophysical surveys, and insufficient indepth excavation of previous geological data.…”

“…(a) Tectonic map of China, showing the location of the Qinling Orogenic Belt(Liu et al, 2022); (b) tectonic subdivision of the Qinling Orogenic Belt, showing the location of the Yechangping Mo deposit (modified afterLiu et al, 2022); (c) geological sketch map of the mining area of the Yechangping Mo deposits (modified afterDing et al, 2015).…”