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The Pulang super-large porphyry Cu polymetallic deposit, located in the Sanjiang area of Yunnan Province, is one of the largest Cu deposits in China. This deposit hosts Cu resources of ~5 × 106 t and other ore-forming elements, such as Mo, Au, Ag, Pb, Zn, Pt and Pd. Recently, obvious hydrothermal vein-type Pb–Zn mineralization, with a Pb + Zn resource of ~0.4 × 106 t, has been detected in the North Ore Section of the deposit. However, the genesis of these Pb–Zn ore bodies, especially their relationship to the major Cu ore bodies in the South Ore Section, remains controversial. We conducted geologic description, fluid inclusion petrography and microthermometry, and C, H, O and S isotope studies to uncover the genesis of Pb–Zn vein-type mineralization in North Pulang. As a result, three types of Pb–Zn veins were identified: a quartz–pyrrhotite–chalcopyrite–sphalerite–galena vein, a quartz–pyrrhotite–sphalerite–galena vein, and a calcite–quartz–pyrrhotite–galena vein. All fluid inclusions in the quartz from different veins are liquid-rich inclusions, with homogenization temperatures in the range of 184 °C–235 °C and salinities between 10.4 wt.% and 17.8 wt.% NaCl eq., indicating that the Pb–Zn ore-forming fluid was a single-phase fluid with a low temperature and low-to-medium salinity. Hydrothermal quartz in different stages displays δDwater values ranging from −46.9‰ to −120.0‰ (V-SMOW), and the calculated δ18Owater values range from 2.4‰ to 4.3‰ (V-SMOW), implying that the mineralization fluids likely originated from magma, with a minor involvement of meteoric water. The δ13CCal values (−2.3‰ to −7.9‰ V-PDB) of calcite indicate that C likely originated from a deep-seated source. The δ34S values of chalcopyrite, pyrite, pyrrhotite and sphalerite reveal that S was possibly derived from magmatic rocks. Based on the above data, it is suggested that the Pb–Zn mineralization in North Pulang was the result of the northward migration of ore-forming fluids that originated from South Pulang along the NE-trending structural fractures. A strong water–rock interaction occurred during the migration process. However, the involvement of meteoric water and accompanied cooling of fluids were most likely responsible for the precipitation of galena and sphalerite. [ABSTRACT FROM AUTHOR]

[Display omitted] • Metallogenic materials and reduced sulfur primarily originated from ore-bearing carbonate rocks. • The precipitation of sulfides was jointly controlled by the W/R reaction and TSR process. • The metallogenic fluids exhibit an evolutionary trend from the metamorphic basement to ore-hosting carbonate rocks. • The Maoping deposit was formed within the late Triassic compressive tectonic setting, with the involvement of Emeishan magmatism. The Maoping Pb-Zn deposit is spatially associated with the late Permian Emeishan basalts and structurally controlled by the NE-trending reverse fault-anticline tectonic system. Nevertheless, there remains limited comprehension of its genetic association with the Emeishan magmatism, as well as the coupling relationship between the overall metallogenic processes and geodynamic evolution. In order to clarify these scientific issues, the syn -ore hydrothermal calcites, sulfides, and sulfates were systematically collected from the representative No. I ore body at different elevations in the Maoping deposit for bulk C-O-S and in situ S-Pb isotopic analyses. Bulk C-O isotopic compositions of syn -ore calcite (δ13C V-PDB = − 4.94 to −0.81‰, δ18O SMOW = +17.66 to +21.16‰) and associated fluids (δ13C V-PDB = −4.56 to −0.48‰, δ18O SMOW = +8.63 to +12.13‰) indicate that C in fluids was mainly derived from ore-bearing carbonate rocks, whereas O was generated by fluid/rock (W/R) interaction process between initial fluids and carbonate rocks. Such process also triggered carbonate dissolution and syn -ore calcite precipitation. In situ Pb isotopic ratios of galena (208Pb/204Pb = 39.116–39.425, 207Pb/204Pb = 15.742–15.767 and 206Pb/204Pb = 18.603–18.753) are more comparable with those of ore-bearing sedimentary rocks, while in situ and bulk S isotopic compositions (δ34S Py+Sp = +20.06 to +23.86‰; δ34S Gn = +17.26 to +18.44‰) of sulfides exhibit high consistency with those of sulfates (δ34S Brt = +17.01 to +19.07‰) within the ore-bearing strata. This suggests that the majority of metallogenic materials and reduced sulfur originated from this source. Meanwhile, the S-Pb isotopic data and relatively high ore-forming temperature (206 ℃) further reveal that the ore-bearing fluids underwent gradual migrated and evolved from the basement to the ore-hosting strata. The Emeishan magmatism not only provided the majority of the thermal power for the fluid circulation, but also contributed a portion of the ore-forming fluids and materials. During the late Triassic, ore-forming fluids migrated along compresso-shear reverse faults to coeval secondary extensional ore-hosting structures due to regional compressive tectonic stresses caused by the Indosinian orogeny and Xuefengshan intraplate orogeny. The mixing of metal-rich hydrothermal fluids with the marine evaporites (mainly gypsum) within sedimentary rocks first triggered thermos-chemical sulfate reduction (TSR) process. The subsequent continuous W/R interaction resulted in a decrease in fluid acidity and temperature, ultimately leading to the precipitation of metal sulfides. [ABSTRACT FROM AUTHOR]

The Jinchanghe Fe-Cu-Pb-Zn polymetallic deposit is located in the northern Baoshan block in the Sanjiang metallogenic belt, southwestern China, and is one of the major large-scale Pb-Zn polymetallic deposits. This region is characterized by numerous diabase intrusions; however, research work is limited. This study elucidated systematic geochemistry and chronology of the diabase closely associated with orebodies in Jinchanghe to provide constraints for magma evolution. The results indicated that the Jinchanghe diabase was enriched in CaO, MgO, and Al2O3 and depleted in TiO2 and P2O5. Large ion lithophile elements were depleted, while for high field strength elements, the ratio of LREEs but depleted in HREEs. The zircon U-Pb dating results suggested that the diabase age could be divided into two stages, indicating the occurrence of two-stage tectonic-magmatic events in the Late Triassic and Early Cretaceous. The results also suggested that the metallogenic age of the Jinchanghe deposit is the Early Cretaceous. Moreover, the age was closely related to the collision after the closure of the mid-Tethys Ocean in the Early Cretaceous. Therefore, the results of this study provide new evidence for the tectonic-magmatic evolution and mineralization of the Baoshan block. [ABSTRACT FROM AUTHOR]

The Pulang porphyry copper deposit recently discovered in northwestern Yunnan province, China, is located at the south end of the Triassic Yidun island arc. To date, 15 mineralized porphyry deposits have been defined in the Pulang area and the copper resource is estimated to exceed 10 Mt. The Pulang deposit, as currently defined, is made up of five ore-bearing porphyry deposits, covering an area of approximately 9 km². Intermediate acidic porphyritic intrusions composed of quartz-diorite, monzodiorite, quartz-monzonite, and granodiorite are widespread in the Pulang area. The alteration zones identified with the porphyry deposits include silicic, potassium silicate, quartz-sericite, and propylitie zones. The porphyry deposits have hornfels at the contact with slate, sandstone, and andesite. Re-Os ages of molybdenite, and Ar/Ar and K-Ar dating of biotite indicate that the Pulang porphyry copper deposit formed during the Indosinian tectonic episode, with the main ore formation taking place from 216 to 213 Ma (Late Triassic, Norian); however, the whole process of hydrothermal activity, including overprinting, may have extended from 235 to 182.5 Ma. [ABSTRACT FROM AUTHOR]

The article presents papers discussing the geological features of rich chemical elements deposits including zinc (Zn), lead (Pb), Germanium (Ge) and silver (Ag) in Northeastern Yunnan, China. It mentions that the special geological features of deposits in the district are different from known types of lead-zinc deposits worldwide. It also mentions that the deposits are close genetic relation with thrustfold structures.

Zircon U-Pb Ages of the Muchang Alkali Granites in Zhenkang Block, Western Yunnan: Implication for the Time Limit on Tectono-Magmatic Activities. [Extracted from the article]

The article discusses preservation and post-ore changes of the porphyry copper deposit in Geza Arc, Yunnan, China. Topics discussed include use of fission track methodology to study regional uplift and erosion in the study, mineralization temperature in copper-polymetallic deposits of the Geza arc, and apatite closure temperature affected by tectonic events after diagenesis and mineralization.

[Display omitted] • The Mengxing Pb–Zn mineralization encompasses sedimentary and hydrothermal stages. • The trace elements of sphalerite suggest the sedimentary stage ore formed at medium–low temperatures, while the metallogenic temperature during the hydrothermal stage was higher. • The δ34S VCDT of sphalerite during the hydrothermal stage averaged at 9.01‰, substantially lower than that of sedimentary stage (27.97‰). • The early stratified ores may be SEDEX type, and the later hydrothermal fluid superimposed the early ores, enriched the deposit. The Mengxing Pb–Zn deposit, which contains up to 1.02 Mt of Pb + Zn metal with an average Pb + Zn grade of ca. 12.13 %, is a representative of sedimentary–reworked deposit in western Yunnan. The orebodies, which are strata–bound and veined, occur in the Silurian Shangrenheqiao formation. The mineralization process has been divided into sedimentary stage and hydrothermal stage. Previous research has primarily focused on the economic ores enriched during the hydrothermal stage. However, the formation of syn –sedimentary ore, responsible for metal pre–enrichment, has been largely ignored. To solve the issue above, the in–situ trace elements and mapping, as well as in–situ S isotopes analyses, were conducted on lamellar sphalerite ore, which retains the characteristics of the syn –sedimentary ore. Analysis of the trace elements revealed that the sphalerite at Mengxing are rich in Ge, Cd, As, Sb and poor in Fe, Mn, In, Sn and Co overall, suggesting a metallogenic environment of medium–low temperature. The LA–ICP–MS trace elemental mapping graph indicated that colloidal sphalerite exhibits the obvious oscillation belts. The dark zonal band of sphalerite is more enriched in Fe, Mn, Cu, Ge, As, Ag, Sb, and Pb, and depleted in Ga, Cd, and Sn, compared to the light zonal band, suggesting the various formation temperature. Based on the equation of the first principal component (PC1*) relating trace elements to mineral formation temperature, it is estimated that ore in the sedimentary stage occurred at relatively lower temperatures (174.74℃ – 203.18℃), while that of the hydrothermal stage occurred at higher temperatures (209.78℃ – 240.18℃). The S isotopic composition of sphalerite indicated a significant distinction between the sedimentary stage (δ34S VCDT = 13.29 ‰ – 37.06 ‰, with an average value of 27.97 ‰) and the hydrothermal stage (δ34S VCDT = −6.45 ‰ – 31.57 ‰, with an average of 9.01 ‰). It is hypothesized that sulfur during the early stage originated primarily from thermochemical sulfate reduction (TSR) of seawater sulfate, while sulfur during the hydrothermal stage was likely influenced by hydrothermal fluid from the deep. In conclusion, the early lamellar ores formed during the Silurian period exhibit characteristics consistent with SEDEX type mineralization, leading to initial metal pre–enrichment, followed by further enrichment of ore grade by superimposed fluid during the hydrothermal stage. [ABSTRACT FROM AUTHOR]

• Yunnan Huangtian large-scale scheelite deposit is an important exploration discovery. • Oblique thrusting system and Tianchong granite branch controlled the deposit. • The tungsten mineralization is related to the Laojunshan granite. The large-scale Huangtian scheelite deposit represents one of the most important such deposits discovered recently in southeastern Yunnan, China. Results of the geological, metallotectonic, and geochemical investigations indicate that this deposit formed in a magmatic hydrothermal system during the Yanshanian period. Its deposition is controlled by the ore-hosted structure of a secondary fold and by interlayer faults (F 0-1 and F 0-2), which are linked to the ore-guided structure of a secondary oblique strike-slip fault (F 7) associated to the regional Maguan deep fault, and to an EW-trending tectonic zone that represents the main metallogenic tectonic system. The oblique strike-slip structure and the Tianchong granitic porphyries, located along the southern margin of the Laojunshan granite body, are primary ore-controlling structures, which directly controlled the movement of the ore-bearing fluid and its subsequent precipitation within the Huangtian scheelite deposit. The distribution of the orebodies is controlled by a group of metallogenic structural surfaces: the fold and fault systems, as well as a silicon-calcium surface. Silicification, fluoritization, and calcitization are the main hydrothermal alterations observed and exhibited a distinct alteration zonation. The hydrothermal mineralization process can be divided into three stages: the quartz-fluorite-(scheelite-tourmaline) stage, the scheelite-quartz-calcite- (fluorite) stage, and the calcite-pyrite-quartz-scheelite stage. The evolution of the mineralizing fluid proceeded as follows: medium-temperature and low-salinity fluid → medium- to low-temperature and low-salinity fluid → low-temperature and low-salinity fluid. The results concerning oxygen and hydrogen isotopic compositions demonstrate that the ore-forming fluids derived from a magmatic fluid mixed with a small amount of meteoric water. Overall, these features indicate that the Huangtian scheelite deposit represents a medium- to low-temperature magmatic hydrothermal deposit that is obviously controlled by the EW-trending tectonic zone. This study demonstrates the significance of such mineral exploration in similar geological regions. [ABSTRACT FROM AUTHOR]

Abstract: Principal component analysis (PCA) is frequently used in geosciences for information extraction. In many applications, masking PCA has been used to create subsets of samples or sub-areas to enhance the effect of the main objects of interest. In this paper we suggest how the representativeness of samples or pixels can be quantified using a fuzzy membership function based on fuzzy set theory. In this new method, the relative importance of pixels or samples can be taken into account using a multivariate statistical method such as PCA. A Fuzzy Masking PCA is proposed and implemented in GeoDAS GIS on the basis of a spatially weighted PCA (SWPCA). This paper introduces the mathematical treatment of the fuzzy masking PCA and follows a case study of identifying the locations of intrusive bodies from geochemical data in the Gejiu mineral district in Yunnan, China. Power-law functions based on the inverse distance from mapped felsic intrusions are applied as weighting functions in FMPCA. The results indicate that fuzzy mask PCA increases the signal-noise ratio of the component representing igneous intrusions and decreases the influence of sedimentary rocks. The areas delineated as potential areas for new intrusions (including buried intrusions) are valuable guides for Sn mineral prospecting. [Copyright &y& Elsevier]