Geochemical Indicators of the Peraluminous W-Cu-Mo-(±Sn-Li-Ta-Nb) Granites in Dahutang Orefield in Northern Jiangxi and Their Significance for Exploration

The origin of Mesozoic granites associated with the Dahutang W-Cu-Mo orefield in north Jiangxi, which host the world’s second largest tungsten deposit, remains a compelling subject despite extensive geochemical and geochronological studies. In this contribution we present new wolframite mineral and bulk-rock geochemistry and monazite U-Pb ages for the Mesozoic granites in aiming to enhance our understanding the petrogenesis of these granites and its coupling relationship with the mineralization. Two magmatic phases and four types of rocks in study area are identified, i.e., the early stage (152-147 Ma) biotite (G1) granite and the late stage (144-130 Ma) two-mica (G2)＋muscovite (G3)＋albite (G4) granite series. These two magmatic phases are temporally coincident with two mineralization stages (~150 Ma and 139-144 Ma). All the Mesozoic granites share the characteristics of high silica content, peraluminosity (A/CNK > 1.1), and low Zr+Nb+Ce+Y values (< 200 ppm), and they are derived from the partial melting of a Proterozoic crustal source. Specifically, the G1 granite, characterized by relatively high MgO (~0.5%), CaO (~1%), and low P2O5(0.13%-0.20%), is classified as an I-type granite. It formed via a relatively higher degree of partial melting at ~766°C (Zr saturation temperatures) driven by biotite breakdown reactions, with minor contributions from mantle-derived materials. In contrast, the G2–G4 granites series exhibits typical peraluminous S-type granite features, such as high Al2O3, Na2O, and P2O5 (mostly >0.2%) contents, and low Sr and Ba contents. They are products of low-degree partial melting that occurred under conditions close to muscovite breakdown at ~735°C. Additionally, both granites show clear geochemical evidence of fluid interaction, as reflected by their elevated trace element and volatile contents: Sn>30 ppm, Cs >35 ppm, F >0.4%, Li >250 ppm, W 10–1000 ppm, Rb >500 ppm, K/Rb values