Work

Whole-rock geochemistry, zircon U-Pb dating, trace element compositions, and Hf isotopes of granitoids from the No. 96–97 target in the Beishan Orogenic Collage: Implications for porphyry fertility

Year: 2025

Type: article

Abstract: • Three magmatic events at 395 Ma, 327–319 Ma, and 310 Ma were identified in the No. 96–97 target in the eastern Gongpoquan magmatic arc. • The related magma derived from partial melting of juvenile mantle-derived crust. • The magmatic rocks from the No. 96–97 target were generated by the southward subduction of the Hongshishan-Baiheshan oceanic plate. • The No. 96–97 target has great potential to form porphyry Cu mineralization. The Gongpoquan magmatic arc is geologically located in the central part of the Beishan Orogenic Collage (BOC) and represents a prospective target for Cu mineralization. However, its geochronological framework, magmatic source, and tectonic setting remain ambiguous. To address these knowledge gaps, the No. 96–97 exploration target in the eastern part of the Gongpoquan magmatic arc was investigated through drilling, which revealed felsic intrusions exhibiting significant mineralization and alteration styles indicative of porphyry-style systems. This study presents integrated whole-rock geochemistry, zircon U-Pb dating, trace element compositions, and Hf isotope from two drill cores (ZK96-1 and ZK97-1). The dating results yielded at least three magmatic events, occurring mainly at 395 Ma, 327–319 Ma, and 310 Ma. These intrusions comprise granite and granodiorite (porphyry), which are calc-alkaline I-type granitoids and enriched in LREEs and LILEs, depleted in HREEs and HFSEs (La N /Yb N = 7.64–18.0; Nb/Ta = 8.02–11.6), demonstrating an island-arc affinity. Zircon ε Hf (t) values of these granitoids range from + 7.32 to + 13.4, suggesting that they predominantly originated from the partial melting of juvenile basaltic material in the lower crust. These findings suggest that the related magmas were formed during the southward subduction of the Hongshishan-Baiheshan oceanic plate. Critically, the diagnostic signatures and geochemical characteristics of the magma suite from the No. 96–97 target exhibit key indicators of high Cu-fertility, such as oxidized conditions. Zircon oxybarometer quantitatively yields f O 2 values of ΔFMQ + 0.46 ± 1.18 and ΔFMQ + 0.61 ± 0.67 for porphyries from ZK96-1 and ZK97-1, respectively. The findings confirm the significant potential for porphyry Cu mineralization in the Gongpoquan arc and provide guidance for future exploration targeting in this region

Source: Ore Geology Reviews

DOI: 10.1016/j.oregeorev.2025.106953