Origin of the Gumao tungsten deposit in the east Dayaoshan of South China: Constraints from geochemistry, wolframite and zircon U-Pb dating, and Hf isotope signatures

Summary schematic of the Gumao W deposit and Early Yanshanian model: F-rich, highly fractionated granitic magmas from ancient lower crust rose along deep faults, precipitating quartz–wolframite veins in Ca-poor wall rocks. • First wolframite-dominated quartz-vein W deposit recognized in the Dayaoshan region, SE Guangxi. • Zircon and wolframite U–Pb ages (162.7 ± 1.3 Ma; 162.6 ± 3.4 Ma) confirm coeval granite emplacement and W mineralization. • A highly fractionated, reduced A-type granite sourced from ancient lower crust (εHf(t) −10.5 to −23.6) extends Late Jurassic Nanling W metallogeny westward and highlights ∼ 170–150 Ma fractionated granites as exploration targets. The Dayaoshan region, situated on the southwestern margin of the Nanling tungsten metallogenic belt, has long been regarded as a Caledonian, scheelite-dominated province. The recognition of the Late Jurassic (∼162 Ma) Gumao quartz vein–type wolframite deposit challenges this paradigm and provides new constraints on tungsten metallogeny in southeastern Guangxi at the junction of the Nanling tectonic domain and the Qin–Hang belt. Here we constrain the timing and petrogenesis of the Gumao mineralized granite using in-situ zircon and wolframite U–Pb geochronology, zircon trace-element geochemistry, and zircon Hf isotopes. Zircon U–Pb dating yields an emplacement age of 162.7 ± 1.3 Ma, whereas wolframite gives a mean U–Pb age of 162.6 ± 3.4 Ma, indicating that granite intrusion and tungsten mineralization were essentially coeval. The mineralized granite is high-SiO 2 and high-K, strongly peraluminous, enriched in HFSE, and characterized by elevated 10,000 × Ga/Al and a pronounced negative Eu anomaly, consistent with a highly evolved, reduced, F-rich A-type affinity. Negative εHf(t) values (−10.5 to −23.6) suggest derivation mainly from partial melting of an ancient, enriched lower crust followed by strong magmatic differentiation. Together with field relationships showing wolframite-bearing quartz veins developed within and adjacent to the granite along NW–SE-trending shear zones, these data define a volatile-rich magmatic–hydrothermal system favorable for wolframite precipitation. The Gumao deposit documents a westward continuation of the Late Jurassic tungsten metallogenic peak into Guangxi and supports the concept of “east-tungsten, westward extension”. We therefore propose that highly fractionated Yanshanian (∼170–150 Ma) granites in eastern Guangxi, particularly faulted granite–wall-rock contacts and greisenized carapaces in low-Ca wall rocks, should be prioritized for quartz vein–type wolframite exploration, guided by Bi–Sn–Be anomalies and F-rich alteration.