ORIGINAL RESEARCH article
Front. Earth Sci.
Sec. Petrology
Volume 13 - 2025 | doi: 10.3389/feart.2025.1616423
This article is part of the Research TopicStructural Processes, Petrogenesis, Mineralization, and Geochronology in the Earth’s CrustView all 8 articles
Petrogenesis and Tectonic implications of Intrusive Rocks in the Jiangjunmu porphyry Deposit, East Kunlun Orogeny, NW China
Provisionally accepted
- 1State Key Laboratory of Ni & Co Associated Minerals Resources Development and Comprehensive Utilization, Jinchang 737100, Gansu, China., Gansu, China
- 2Jinchuan Nickel & Cobalt Research and Engineering Institute, Jinchang 737100, Gansu, China., Gansu, China
- 3School of Earth Sciences and Resources, China University of Geosciences Wuhan, Wuhan, Hubei Province, China
- 4State Key Laboratory of Geological Processes and Mineral Resources, School of Earth Sciences and Resources, China University of Geosciences Wuhan, Wuhan, Hubei Province, China
- 5Geological Survey Institute, China University of Geosciences, Wuhan 430074, China., Wuhan, China
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The newly discovered Jiangjunmu Cu–Au deposits are hosted within granodiorite porphyry and K-feldspar granite of the East Kunlun metallogenic belt. Previous understanding of these deposits has been limited due to a lack of comprehensive isotopic data. To address this gap, we present new zircon U–Pb geochronology, whole-rock geochemistry, and Sr–Nd–Pb–Hf isotopic analyses of the Jiangjunmu intrusive rocks. Both intrusive rock samples exhibit nearly identical REE patterns, suggesting they originated from the same source area. The K-feldspar granite (²⁰⁶Pb/²³⁸U age: 228 Ma) and the Jiangjunmu granodiorite porphyry intruded into the Jiangjunmu K-feldspar granite porphyry (²⁰⁶Pb/²³⁸U age: 234 Ma). They exhibit initial (⁸⁷Sr/⁸⁶Sr)ᵢ ratios of 0.70884–0.70944 and 0.70555–0.70913, εNd(t) values of –4.32 to –5.24 and –8.27 to –8.93, ²⁰⁷Pb/²⁰⁴Pb ratios of 15.615–15.677 and 15.664–15.682, and ²⁰⁸Pb/²⁰⁴Pb ratios of 38.443–38.544 and 38.526–38.650, respectively. The Jiangjunmu K-feldspar granite also has high Rb/Sr ratios (0.82), low MgO (0.66–1.19 wt.%), Cr (6.6–13.6 ppm), Ni (4.4–6.4 ppm), and Co (55.9–97.2 ppm) contents, indicating an origin from a thickened lower continental crust (TLCC) magma source by partial melting (Sr/Y: 9.4–15.8; La/Yb: 25.6–35.5). Its lower Mg# values (36– 39), relatively higher (⁸⁷Sr/⁸⁶Sr)ᵢ ratios, lower Sr concentrations (179.8–266.1 ppm), and εHf(t) values (–8.18 to –3.83) suggest that a more evolved upper continental crustal component (heterotypic sandstone) contributed to the formation of the K-feldspar granite during magmatic evolution. The presence of numerous mafic magmatic enclaves (MMEs) in the granodiorite porphyry suggests that the Cu (Au) contents of the Jiangjunmu deposit may have been derived from a mantle source. In association with the tectonic background and regional research, the Jiangjunmu granodiorite porphyry and K-feldspar granite (Th/Sm: 4.2–5.1; Th/Yb:11.5–14.8) formed in a post-collisional orogenic extensional setting after the closure of the Paleo-Tethys Ocean.
Keywords: Jiangjunmu granodiorite porphyry, Jiangjunmu K-feldspar granite, East Kunlun metallogenic belt, Mafic magmatic enclaves, Thickened lower continental crust
Received: 22 Apr 2025; Accepted: 08 Sep 2025.
Copyright: © 2025 Zhen, Xian, Lin, Bo, ye, Khan and Tahir. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Junaid Khan, School of Earth Sciences and Resources, China University of Geosciences Wuhan, Wuhan, 430074, Hubei Province, China
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