Physicochemical conditions of hydrothermal fluids during indium endowment in the Dulong giant tin polymetallic deposit, SW China

Structural characteristics and evolution processes of intracratonic strike-slip fault systems: A case from central Sichuan Basin, SW China

Tracing scale-dependent sediment provenance and dual-pathway dynamics across the surface-subsurface interface of a karst agroforestry catchment, SW China

Live fuel moisture content estimated using spectral indices to assess fire activity in the mountainous forests of Southwest China

The ore-forming process of the Maoping MVT Pb-Zn deposit in northeastern Yunnan, SW China: Constraints from trace element compositions of pyrite

Source of ore-forming fluid and metallogenic mechanism of the Lailishan tin deposit in western Yunnan, SW China: Constraints from fluid inclusions and H–O–S isotopes

Deciphering ore-forming processes in the Daping orogenic gold deposit, SW China: constraints from in situ sulfur isotope and pyrite trace elements

Timing, ore genesis, and hydrothermal evolution of the Mahuaping W-Be-F deposit, SW China

A brief case study of unshielded georadar applied to karst peak-cluster depression in SW China

ABSTRACT Numerous Palaeozoic ophiolites occur in the Changning – Menglian suture zone in southwestern Yunnan Province, China, which are important for reconstructing the evolution of the Proto- and Paleo-Tethys oceans. In this study, zircon U-Pb age and whole-rock geochemical data were acquired for amphibolites in the Nantinghe ophiolites within this suture zone, to constrain the timing of closure of the Proto-Tethys Ocean. The amphibolites can be classified into epidote amphibolites and migmatitic garnet-bearing amphibolites, with the latter containing leucocratic and melanocratic domains. Zircon U-Pb dating yielded 206Pb/238U ages for zircon cores of 466–456 and 480.8 ± 5.1 Ma (weighted-mean), which represent the protolith age. Zircon rims have ages of 445–436 Ma, which date metamorphism or anatexis. The epidote amphibolites have relatively low SiO2 and high Al2O3, MgO, and TFe2O3 contents, are light rare earth element (REE) enriched and heavy REE depleted, and have negative Rb, Th, Nb, Ta, Zr, and Hf anomalies in trace element diagrams. These geochemical affinities suggest a protolith origin from arc-related magmatism. Synthesizing documented records of Early Palaeozoic calc‑alkaline igneous rocks, these rock suites demonstrate that subduction of the Paleo‑Tethys Oceanic lithosphere had initiated in the Early Ordovician with its peak activity occurring in the Middle Ordovician (466–456 Ma).The metamorphic ages (445–436 Ma) of the garnet-bearing amphibolites are comparable to those of garnet amphibolites in Taoxinghu and high-pressure mafic granulites in Xiangtaohu in the Longmucuo – Shuanghu area. They record the timing of continental collision accompanying closure of the Proto-Tethys Ocean. The Longmucuo – Shuanghu – Changning – Menglian suture zone had a similar Early Palaeozoic tectonic evolution to that of the Proto-Tethys Ocean in areas such as North Qilian, East Kunlun, and northern Qaidam.

Yi-ethnic enclosure walls as indigenous innovation for mitigating phosphorus loss in sloping croplands of the Anning River Basin, SW China

Petrogenetic difference of Eocene granitic bedrocks controls light and heavy REE enrichment in regolith-hosted deposits, Tengchong terrane, SW China

Pliocene humid subtropical climate in Central Yunnan (SW China) and the anthropogenic warming-driven extinction threat to Nyssa species

Processes of helium enrichment in the Ediacran Dengying natural gas pool of the Southwestern Sichuan Basin, SW China

A mixed-fluid genetic model for the baiceng fluorite deposit, SW China: Deciphering the magmatic thermal driver and basinal fluid sources

The mound-shoal complex (MSC) is an effective reservoir for the accumulation of solid minerals and hydrocarbons within carbonate strata. Previous studies have emphasised the alteration effect of diagenetic fluids (including seawater and atmospheric freshwater) on MSC, leaving a gap in understanding how strike-slip fault control MSC reservoir. To fill this gap, a multi-scale fracture identification technique, based on frequency separation, is used to extract information about fractures at various scales in this study. Based on the restoration of sedimentary geomorphology, waveform classification techniques are used to characterise the distribution of the MSC in Ediacaran Dengying 2nd Member. The results indicate that platform-margin strike-slip faults control the migration of the platform margin and, thus controlling the large-scale MSC distribution. Strike-slip faults within the platform can cause surface deformation, leading to topographic variations that create new high-energy zones favourable for the growth of MSC, thereby facilitating MSC-building. The platform-margin strike-slip fault during the end of Ediacaran not only provided topographic conditions for the formation of the MSC, but also promoted the alteration of the MSC by atmospheric fresh water. Later-activated strike-slip faults provided migration pathways for hydrothermal minerals, which hindered the preservation of the reservoir quality in the MSC. The findings of this study are valuable for future exploration of MSC reservoir, as they will enhance the understanding of the controlling factors for MSC reservoir.

Depositional environments of a mixed siliciclastic-carbonate system: A case study of the late Ediacaran sedimentary succession in the northern Sichuan Basin (SW China)

Distribution and enrichment of radioactive elements (Th, U) in Nb-Zr-REY-Ga polymetallic clay horizons of the Late Permian (Lopingian) coal-bearing strata, eastern Yunnan, SW China: natural gamma-ray anomalies response to critical metals

Interstitial microstructures in igneous rocks record key evidence of late-stage evolution processes. In order to constrain the late-stage evolution of a Baima gabbro pegmatite (Panxi region, SW (Southwestern Sichuan Province), China), we investigated its mineral compositions and late-stage microstructures. These microstructures include replacive symplectites and fish-hook clinopyroxene. Replacive symplectites include fine-grained lamellar intergrowths of anorthite (An)-rich plagioclase + clinopyroxene/amphibole/biotite that are rooted to Fe-Ti oxides and replacing nearby plagioclase primocrysts (Type I) and intergrowths of An-rich plagioclase + clinopyroxene/amphibole that are rooted to olivine and replacing nearby plagioclase primocrysts (Type II). Rare replacive symplectites composed of biotite + plagioclase are also present. Those replacive symplectites and fish-hook clinopyroxene grew at a late magmatic stage with temperatures of 867–1023 °C. An-rich plagioclase in the replacive symplectites and fish-hook textures have An contents up to 94 mol.%, much higher than those of plagioclase primocrysts. Interstitial microstructures are interpreted to reflect interaction between primocrysts and an Fe-rich residual interstitial liquid, consistent with separation and migration of conjugate immiscible melts in a crystal mush. We propose that the hydrous interstitial melt in the Baima gabbro pegmatite may have undergone silicate immiscibility during late-stage magma crystallization. As the crystal fraction increased, crystal-mush compaction and porous melt migration likely became the primary controls on the evolution of the late-stage interstitial melt, rather than convection or diffusion.

The Xiaotunxiang deposit, a newly discovered large-scale fluorite resource (1.28 Mt ore reserves) in southwestern Guizhou Province, China, provides a critical case study for understanding fluorite mineralization in the region. To constrain its genesis, this study integrates detailed ore deposit geology with mineralogy, trace element geochemistry, and strontium isotope analysis of fluorite. The ore mineral assemblage is dominated by fluorite, quartz, and calcite, with minor amounts of barite and pyrite. Trace element data reveal significant enrichment in Ti, Cr, Mo, and Sb relative to the upper continental crust. Fluorite exhibits moderate total REE contents (26.8–138 ppm), slight heavy REE enrichment (ΣLREE/ΣHREE = 0.17–1.88), pronounced negative Ce anomalies (δCe = 0.59–0.72), and negligible Eu anomalies (δEu = 0.95–1.14). These geochemical signatures are closely comparable to those of nearby fluorite deposits (Qinglong, Gaoling, and Getang), indicating a shared source of ore-forming materials. Strontium isotope ratios (87Sr/86Sr = 0.707468–0.707682) are consistent with local carbonate wall rocks, confirming their role as the primary source of calcium. We conclude that the Xiaotunxiang deposit formed from a low-temperature hydrothermal system where fluorine and associated metals were likely sourced from the Emeishan basalts, while calcium was derived from the interaction of acidic fluids with carbonate host rocks. Precipitation was ultimately triggered by fluid–rock (water/rock) interaction, classifying Xiaotunxiang as a carbonate-hosted hydrothermal deposit.