Geochronology and Geochemical Characteristics of Mineralized and Barren Intrusions in the Fengyan Porphyry-Skarn Zn-Pb-Mo Deposit, Central Fujian Region, and their Metallotectonic Implications
Bo XING , Yu SHANG , Wei ZHENG , Xiaoniu XIAO , Hongyu LI , Huan LIU , Yong WU , Wuyan HUANG
Acta Geologica Sinica (English Edition) ›› 2025, Vol. 99 ›› Issue (6) : 1756 -1775.
Porphyry-skarn deposits are genetically associated with multistage intrusive complexes. However, their ore fertility varies markedly, as exemplified by the coexistence of mineralized and barren intrusions within a single pluton. The factors controlling this disparity, particularly whether high oxygen fugacity (fO2) and volatile-rich magmas are essential, remain poorly constrained. This study investigates the Fengyan Zn-Pb-Mo deposit in the central Fujian region by comparing geochronological and geochemical features of ore-associated granite porphyry and barren monzogranite. SIMS zircon U-Pb dating reveals the mineralized intrusion crystallized at 142.5 ± 1.6 Ma, significantly later than the barren monzogranite (150.3 ± 1.3 Ma). The ore-associated porphyry exhibits higher magma temperatures and sulfur contents, yet lower fO2 and water content relative to the barren monzogranite. Hf-O isotopes reveal greater mantle input in the ore-related granite porphyry (εHf(t) = –11.5 to –7.5; δ18O = 6.50‰ to 7.11‰) than in the ore-barren monzogranite (εHf(t) = –16.0 to –9.5; δ18O = 6.81‰ to 8.00‰). Furthermore, elevated fO2 and volatile-rich conditions are not prerequisites for Zn-Pb-Mo mineralization, implying other factors are key. The barren rock formed during low-angle subduction of the Paleo-Pacific plate, whereas the mineralized porphyry originated during slab rollback and lithospheric extension. This study highlights that medium–low fO2 (mean ΔFMQ +0.39 in granite porphyry vs. +1.80 in monzogranite), volatile-poor magmatic systems in extensional settings can form significant mineralization, offering new insights for exploration in central Fujian and analogous regions.
geochronology / zircon Hf-O isotopes / fertile and barren magmatic rocks / SIMS U-Pb dating / Fengyan Zn-Pb-Mo deposit / central Fujian region
2025 Geological Society of China
/
| 〈 |
|
〉 |
PDF
