PlumX Metrics
Embed PlumX Metrics

Two discrete late Paleozoic skarnizations recorded by garnet from the Kekesala Fe-Cu deposit, NW China: Implications for regional magmatic-hydrothermal episodes in the northern Yili Block

Ore Geology Reviews, ISSN: 0169-1368, Vol: 176, Page: 106408
2025
  • 0
    Citations
  • 0
    Usage
  • 0
    Captures
  • 0
    Mentions
  • 0
    Social Media
Metric Options:   Counts1 Year3 Year

Article Description

Accurately determining the episodic mineralizing of ore deposits critically relies on robust geochronology, which is crucial for understanding regional metallogenesis, linking them with geodynamic processes, and guiding mineral exploration. The Kekesala deposit, hosted in the contact between the granodiorite intrusions and metasomatized limestones, is a typical Fe-Cu skarn deposit in the northern Yili Block. However, the reported ages of Mo mineralization postdated magmatism by ∼70 m.y., so the temporal and genetic relationship between intrusions and skarnizations remains controversial. To address aforesaid issues, we combine new zircon U-Pb, garnet Sm-Nd, and in situ garnet U-Pb ages at Kekesala while comparing them to previously reported regional geochronological data. Three types of garnet were identified by color and textural differences at Kekesala: (1) yellowish-green garnet with fine-scale oscillatory zoning (type 1); (2) dark garnet with coarse-scale oscillatory zoning (type 2); and (3) reddish-brown garnet without composition zoning (type 3). U-Pb ages for type 1 and type 2 garnets were comparable, ranging from 366.8 ± 4.3 Ma to 365.4 ± 3.6 Ma, which is consistent with garnet Sm-Nd isochron age (367 ± 12 Ma) and zircon U-Pb ages of granitic intrusions (367.2 ± 2.2 Ma to 365.9 ± 2.1 Ma), suggesting a genetic relationship between the Late Devonian skarnization and the exposed granitic intrusions in the Kekesala ore district. Exposed granitoids could be primarily responsible for Fe-Cu mineralization during the Late Devonian based on their high oxygen fugacity and water content, coupled with field observations. In comparison, type 3 garnet provided much younger U-Pb ages of 292.6 ± 4.3 Ma and 294.7 ± 5.3 Ma, which coincide with the previously published molybdenite Re-Os ages (ca. 295–290 Ma), suggesting that superimposed skarn Mo mineralization occurred during the Early Permian. Given that the Early Permian intrusion is absent in the ore district but widespread occurrence in the adjacent Kendenggaoer area with associated economic Cu-Mo deposits, we speculate that a hidden intermediate-felsic intrusion may be responsible for this skarn Mo mineralization in the Kekesala deposit. Therefore, our new geochronological results of the three types of garnet reveal two discrete Late Paleozoic skarn mineralizations in the Kekesala Fe-Cu skarn deposit. Compilation of available geochronological data of magmatism and magmatic-hydrothermal mineralization in the northern Yili Block indicates that the two-stage skarnizations coincide with the regional episodic magmatic-hydrothermal events, which are controlled by the geodynamic regime from oceanic subduction to post-collisional extension that accompany the extinction of the Junggar Ocean during the Late Paleozoic. The model for regional skarn metallogeny during Late Devonian–Early Carboniferous in the northern Yili Block should also consider the possible overlap and remobilization of metal by the magmatic-hydrothermal event during Late Carboniferous–Early Permian. Our study demonstrates the reliability of skarn garnet U-Pb dating in identifying discrete metallogenic events in complex skarn systems.

Bibliographic Details

Provide Feedback

Have ideas for a new metric? Would you like to see something else here?Let us know