Work

District-scale variations in sphalerite texture and chemistry from the Laojunshan Zn-polymetallic ore district, Southwest China

Year: 2026

Type: article

Abstract: Critical metals such as indium are increasingly recognized in magmatic-hydrothermal ore systems, but whether their distribution can serve as a reliable guide for mineral exploration remains uncertain. The Laojunshan Zn-polymetallic district in southeastern Yunnan Province, China, hosts significant indium resources (>7000 tons In), genetically related to the Cretaceous Laojunshan granite. The district also contains numerous deposits distributed along a proximal-to-distal gradient relative to the magmatic center, providing an ideal locality for evaluating how indium in sphalerite varies with distance from the magmatic center. This study systematically determined the in-situ trace element compositions and sulfur-lead isotopic characteristics of sphalerite from four deposits distributed along a proximal to distal transect relative to the intrusion. The results reveal a regional-scale decrease in sphalerite indium contents from proximal to distal deposits, accompanied by systematic variations in ore-forming temperatures and sulfur fugacity. Proximal sphalerite contain high indium contents (IQR = 53.9–1345 ppm), elevated GGIMFis temperatures (IQR = 319–436 °C), and relatively oxidized sulfur fugacity conditions (log 10 ( f S 2 ): IQR = -6.80 to −2.79), whereas distal deposits show lower values (In < 50 ppm, IQR = 238–385 °C; log 10 ( f S 2 ): IQR = -9.91 to −3.97). Sulfur-lead isotopic signatures indicate that the ore-forming materials were primarily derived from the Cretaceous granitic magma. Comparisons across the Laojunshan district reveal that within each deposit, only early-stage sphalerite preserves primary magmatic signatures, whereas late-stage sphalerite reflects local buffering that masks spatial trends. These results demonstrate that indium content in sphalerite can serve as robust indicators for tracing magmatic centers and the spatial location of potentially hidden intrusions. This study highlights the value of district-scale integration of trace element data in sphalerite, while emphasizing the need to combine such analyses with detailed textural characterization of sphalerite.

Source: Ore Geology Reviews

DOI: 10.1016/j.oregeorev.2026.107516

Authors: Shi-Hui Pan, Kai Luo, Alexandre Cugerone, Tao Wu, Jin Hu, Jia-Xi Zhou

Institutions: Yunnan University, University of Geneva, Guizhou University of Engineering Science, Yuxi Normal University

Language: English

Topic: Geochemistry and Geochronology of Asian Mineral Deposits

Subfield: Geochemistry and Petrology

Field: Earth and Planetary Sciences

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $3,310

Funders: National Natural Science Foundation of China, Yunnan Provincial Science and Technology Department