Abstract
Chuankou tungsten (W) ore field, with an estimated WO3 reserve exceeding 300,000 tonnes, is so far the largest Indosinian (Triassic) granite-related W ore field in South China. However, the precise emplacement ages, sources of granitoids, and their relationship with W mineralization are still not well understood. In this research, four main magmatic stages (G-1 to G-4) have been identified in the Chuankou ore field, including G-1 (phase I, biotite monzogranite), G-2 (phase II, two-mica monzogranite), G-3 (phase III, fine-grained granite), and G-4 (phase IV, granite porphyry). LA-ICP-MS U-Pb dating of zircon grains from granitoids of the Chuankou W ore field yields emplacement ages of 230.8 ± 1.6 Ma, 222.1 ± 0.56 Ma, 203.1 ± 1.6 Ma, and 135.5 ± 2.4 Ma, respectively. Granitoids from the Chuankou ore field contain a large amount of peraluminous minerals such as biotite, musvite, garnet and tourmaline. Geochemically, the granitoids have high Si and Al (A/CNK > 1.1) content but low alkali, Fe, Mg, Mn, and Ca content. Moreover, there is enrichment of Rb, Zr, Hf, Th, and U, but depletions of Ba, Sr, P, and Ti. The granitoids have especially low Zr + Nb + Ce + Y and high Rb/Ba ratios, further indicating a highly fractionated S-type granite affinity with a significant crystal fractionation process in regard to K-feldspar, plagioclase, biotite, Ti-bearing minerals (except rutile), zircon, apatite, allanite, and monazite. Whole-rock εNd(t) and TDM2 values are −10.77 and 2090 Ma for G-1, −9.09 to −7.47 and 1764–1684 Ma for G-2, −10.07 to −6.53 and 1669–1471 Ma for G-3, respectively, indicating that the Chuankou granitoids were derived from two episodes of partial melting of the Paleoproterozoic to Mesoproterozoic metamorphic basement. Trace elements within the zircons and whole-rock geochemistry yielded evidence of the close relationship between W mineralization and G-1 and G-2 granitoids of the Chuankou ore field. The batholith of the Chuankou ore field was formed 20–10 Ma later than the peak age of the collisions orogeny and formed in a post-collisional setting.
Highlights
South China (SC) is renowned for its extensive magmatism and the giant ore deposit clusters of W, Sn, Mo, Bi, Pb, Zn, Sb, U, Be, Nb, Ta, and REEs in the Yanshanian period [1,2,3,4,5].These ore deposits host more than 90% of China’s W resources; over 56% of global W resources [1,2,3]
170 Ma and emphasized that the mineralization of W occurred in the early Middle Jurassic
Conflicting data by Peng et al and Qin et al indicate that the ore-forming age varies from 224 to 230 Ma based on Re-Os isotopic chronology data of molybdenite [31,56]
Summary
South China (SC) is renowned for its extensive magmatism and the giant ore deposit clusters of W, Sn, Mo, Bi, Pb, Zn, Sb, U, Be, Nb, Ta, and REEs in the Yanshanian period [1,2,3,4,5]. These ore deposits host more than 90% of China’s W resources; over 56% of global W resources [1,2,3]. We present new zircon U-Pb ages, major and trace element characteristics, Sr-Nd isotopic compositions of granitoids from the Chuankou W ore field to constrain the source, magmatic genesis, and their relationships with W deposits
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