Polymetallic Skarn Deposit Research Articles

Geochronology and geochemistry of the granitoids and ore – forming age in the Xiaoyao tungsten polymetallic skarn deposit in the Jiangnan Massif tungsten belt, China: Implications for their petrogenesis, geodynamic setting, and mineralization

The Xiaoyao tungsten polymetallic skarn deposit in the eastern Jiangnan Massif of Yangtze Block is located at the contact between a granodiorite pluton and Sinian–Cambrian limestone. The intrusions in the tungsten-rich district comprise the Xiaoyao and other granodiorite plutons and granite porphyry dikes. The age determinations by LA–ICP–MS U–Pb dating of zircons indicate that the granodiorite formed at 149.4±1.1Ma, whereas the granite porphyry was emplaced at 133.2±0.7Ma. Re–Os dating of molybdenite from the skarn orebodies yielded a weighted average age of 148.7±2.3Ma (n=5). These ages indicate that the tungsten mineralization is temporally related to the granodiorite. The granodiorites are metaluminous (A/CNK=0.86–0.98) and in the high-K calc-alkaline series. They contain hornblende and have a negative correlation between P2O5 and SiO2, indicating that they are typical I-type intrusions. The granite porphyries exhibit high alkali contents (Na2O+K2O=7.97–9.53%), elevated FeOT/(FeOT+MgO) ratios (0.83–0.94), high concentrations of Zr, Nb, Ce, and Y, and high Zr saturation temperatures (average of 812°C); thus, they are geochemically similar to A-type intrusions. The initial 87Sr/86Sr and εNd(t) values range respectively from 0.7074 to 0.7083 and from −7.9 to −1.3 for the granodiorite, and from 0.7008 to 0.7083 and from −6.3 to −4.7 for the granite porphyry. In addition, two-stage Nd model ages (T2DM) of 1.0–1.6Ga for the granodiorite and 1.3–1.4Ga for the granite porphyry indicate that the Proterozoic crustal rocks of the Shangxi Group could have contributed to the Xiaoyao magmas. The rhenium contents of the molybdenite grains vary from 32 to 136ppm, suggesting that the molybdenum was derived mainly from a mixture of mantle and crustal sources. Based on the new geochemical data and regional geological investigations, we propose that the Late Jurassic mineralization-related I-type granodiorite was derived from the Neoproterozoic Shangxi metamorphic rocks with some additional input of mantle material. The magmatism was triggered by asthenospheric upwelling induced by slab tearing during oblique subduction of the paleo-Pacific plate beneath the South China Block.

Multiphase formation of the Obří důl polymetallic skarn deposit, West Sudetes, Bohemian Massif: geochemistry and Re–Os dating of sulfide mineralization

The Obři důl Fe–Cu–As polymetallic sulfide skarn deposit is developed in a metamorphic series in the West Sudetes, Bohemian Massif. It consists of lenses of marble, calc–silicate rocks, and skarns. We studied the Gustav orebody, which is located few hundred meters away from the contact with a large, late-orogenic Variscan Krkonose–Jizera Plutonic Complex (KJPC) emplaced into shallow crust. Mineralogical and fluid inclusion study evidence indicates that the main sulfide stage, dominated by pyrrhotite, arsenopyrite, and chalcopyrite originated from aqueous hydrothermal fluids with salinity up to 8 wt% NaCl eq. with minimum homogenization temperatures ranging from 324 to 358 °C. These fluids mainly replaced carbonate-rich lithologies. Carbon, oxygen, and strontium isotope data in Ca-rich rocks imply total overprinting by channelized metasomatic fluid flow, which is most probably related to the intrusion of the KJPC, whereas δ34S values of sulfides argue for a magmatic source of sulfur. The Re–Os age of arsenopyrite overlaps published age data for the KJPC and suggests synchronous formation of the main sulfide mineralization and pluton emplacement.

Stanniferous magnetite composition from the Haobugao skarn Fe–Zn deposit, southern Great Xing'an Range: Implication for mineral depositional mechanism

The Great Xing'an Range in north‐eastern China hosts numerous super‐large Ag–Pb–Zn deposits and some Fe–Sn deposits. The Mesozoic Haobugao Fe–Zn polymetallic skarn deposit in the southern Great Xing'an Range is contemporaneous with the regional Ag–Pb–Zn mineralization. Numerous ore bodies are hosted in the Lower Permian carbonate strata or along the contact with the Early Cretaceous granite. According to the field and systematic petrography and mineralography research, the Haobugao mineralization phases are divided into 3 paragenetic stages: prograde stage, retrograde stage, and sulphide stage. Magnetite mainly occurred in the retrograde stage and replaced the anhydrous skarn minerals (e.g., garnet and diopside). Two types of magnetite (Mag1 and Mag2), including 6 subtypes, can be distinguished based on the scanning electron microscopy and back scattered electron images. Electron probe microanalysis and laser ablation inductively coupled plasma mass spectrometer analysis were used to determine major and trace elements in different types of magnetite. Mag1 has higher Ti and V concentrations than Mag2, indicating a relatively higher depositional temperature. Mag1 also contains relatively higher Mg and Mn concentrations, coupled with much lower Si and Al concentrations, which reflects a low fluid/rock ratio at the site of Mag1 deposition. Element variation features of Mag1 and Mag2 reveal that the Haobugao mineralization fluids gradually evolved from high‐temperature and low fluid/rock ratio fluids to relatively low‐temperature and high fluid/rock ratio fluids. However, electron probe microanalysis data of Mag2 display significantly higher Sn concentrations (up to 2.82 wt.%) than that in Mag1, which indicates that Sn can be incorporated into magnetite crystal lattice. We propose a possible substitution mechanism of Sn4+ + Mn2+ = 2Fe3+, supported by the strongly positive correlation between Sn4+ and Mn2+, whereby a substitution of Sn4+ for Fe3+ in octahedral sites of magnetite requires a compensatory substitution of Mn2+ for Fe3+ to maintain the charge balance.

Jurassic magmatism related Pb-Zn-W-Mo polymetallic mineralization in the central Nanling Range, South China: Geochronologic, geochemical, and isotopic evidence from the Huangshaping deposit

The Nanling Range in South China is characterized by extensive Mesozoic magmatism and coeval nonferrous and rare metal mineralization. Huangshaping is a world-class Pb-Zn-W-Mo polymetallic skarn deposit in the central Nanling Range. Magmatic rocks occurring in this ore district include quartz porphyry, granite porphyry, granophyre, dacite porphyry, and aplite, with only the first three granitoids genetically associated with polymetallic mineralization. Most of the orebodies are constrained within the contact zones as skarn and veins between these granitic stocks and the carbonate wall rocks.Since the age of the quartz porphyry is still controversial, and studies of the dacite porphyry and aplite are absent, we focus on these magmatic rocks first. LA-ICP-MS zircon U-Pb dating suggests that the crystallization ages of the quartz porphyry, dacite porphyry, and aplite are 154.3±1.9Ma, 158.1±0.8Ma, and 148.4±3.4Ma, respectively. Combined with previously published age data, we infer the evolutionary sequence of magmatic rocks should be dacite porphyry→quartz porphyry→granite porphyry (granophyre)→aplite. The quartz porphyry, dacite porphyry, and aplite yield high contents of high field strength elements (Zr+Nb+Ce+Y=255–440ppm), high ratios of 10,000×Ga/Al (2.6–3.2), and prominent depletions in Ba, Sr, Eu, P, and Ti, indicating their crustal affinities to A-type granites. They have negative εNd(t) values (−9.4 to −7.0) and high initial Pb isotopic ratios (206Pb/204Pbi=18.307–18.644, 207Pb/204Pbi=15.689–15.742, 208Pb/204Pbi=38.589–38.986), suggesting that they were probably derived by partial melting of ancient granulitic crustal materials.The sulfide minerals exhibit a wide range of δ34SV-CDT values from −22.6 to 24.2‰, with 206Pb/204Pb of 17.669–19.708, 207Pb/204Pb of 15.492–15.714, and 208Pb/204Pb of 37.880–39.789, indicating that sulfur, lead, and other associated metals were derived from a mixture of magmatic components and the Carboniferous wall rocks. Fluid inclusions in pyrrhotite, sphalerite, and marmatite samples have 3He/4He ratios of 0.12 to 1.53 Ra, with calculated mantle helium proportions of 1.3 to 18.9%, indicating a predominantly crustal origin for the ore fluids, with minor inputs from the mantle. The Huangshaping deposit is a typical example of the genetic relationship both spatially and temporally between Jurassic magmatism and polymetallic metallogeny in the Nanling Range.

Geochemistry of magnetite from theHuanggangskarn iron–tin polymetallic deposit in the southernGreat Xing'an Range, NE China

The Huanggang iron–tin polymetallic skarn deposit is located in the southern Great Xing'an Range. According to the ore types and mineral assemblages, the paragenetic sequence of the Huanggang deposit can be divided into three stages, and these magnetite grains were mainly formed at the retrograde and sulphide skarn stages. The magnetite (sample HG12‐13) from the early retrograde stage is represented by fine‐grained magnetite cutting across coarse‐grained magnetite surrounded by quartz and calcite. The magnetite (sample HG12‐73) from the late retrograde stage is locally replaced by haematite along the margin or interior and is surrounded by calcite. The magnetite (sample HG12‐88) from the early sulphide stage is characterized by obvious core–rim textural features. The magnetite (sample HG‐62) from the late sulphide stage is featured by zone‐like magnetite occurring along the margin and interior of the primary magnetite.Laser ablation inductively coupled plasma mass spectrometry was used to obtain trace element concentrations of magnetite from the different mineralization stages in order to better understand the geochemical variations in the ore‐forming process. Some magnetite grains have abnormally high Mg, Al, K, Cu, Zn, and Sn due to the presence of numerous inclusions (e.g., chlorite, sylvite, chalcopyrite, sphalerite, and cassiterite). In general, magnetite grains from the different mineralization stages demonstrate similar bulk continental crust normalized trace elements patterns, suggesting that they share a similar origin. The increasing Si + Al/Mg + Mn ratios and decreasing Mg + Mn contents for magnetite show an increasing fluid–rock ratio from the retrograde to sulphide stage. Co contents of magnetite decrease abruptly from the retrograde stage to the sulphide stage, whereas Mn contents show the reverse trend, which is affected by minerals coprecipitating with magnetite. A zoned magnetite from the sulphide stage shows decreasing Ti and V contents from core to outer rim; the variation of Ti and V may be related to the temperature or oxygen fugacity. Magnetite compositions from the Huanggang deposit are similar to those from Fe, Cu‐polymetallic, or other skarn deposits, but display more variable compositions than previously presented. Our study demonstrates that the evolution of magnetite in the skarn deposit and trace element of magnetite could be a powerful tool in determining the origin of skarn iron deposit.

Multistage Skarn-Related Tourmaline From the Galinge Deposit, Qiman Tagh, Western China: A Fluid Evolution Perspective

Abstract The Galinge skarn deposit, the largest iron polymetallic skarn deposit in the Qiman Tagh metallogenic belt (western China), was formed via multi-stage fluid-rock interactions. It is divided into six ore domains from east to the west. Skarn-related tourmaline is ubiquitous in the V ore domain of the Galinge deposit, occurring both in the altered basaltic andesite (Tour-I) and in the sandstone (Tour-II). The tourmaline composition in both rock types is within the dravite–uvite solid solution. Some Tour-I crystals show compositional growth zoning in which the early stage uvite cores (Gen-1) are overgrown by second-stage dravite rims (Gen-2). Some Tour-I crystals also show overgrowth rims and fracture-infilled textures (Gen-3). Some other Tour-1 tourmalines without clear growth zoning (Others) show an intermediate composition between Gen-2 and Gen-3. The varying composition of the zoned tourmalines records important information about the evolving hydrothermal fluids and host rocks. Gen-1 and Gen-2, displaying a narrow and high range of Fe 2+ /(Fe 2+ + Mg) ratios, are much more equilibrated with mafic host rocks. The alkaline (K + Na) content of tourmalines is associated with the salinities of the ore-forming fluids. The lowest Na + K content of Gen-3 indicates that it may have been equilibrated with a low-salinity fluid environment in which the concentration of metal-chlorite complexes decreased. The Gen-3 stage is considered to be the main ore-forming event. Tour-II have similar Ca/(K + Na + Ca) ratios with Gen-1 and Gen-2 ratios, which indicates that they are contemporarily formed by the same fluid as Tour-I. Through compositional comparison of the tourmalines with those from other hydrothermal deposit types, the Galinge skarn-related tourmalines are overwhelmingly controlled by the MgFe –1 substitution mechanism. This is different from the compositions of tourmalines in porphyry, VMS, and vein-greisen type deposits, which are, respectively, controlled by the Fe 3+ Al –1 , (CaMg)(NaAl) –1 and (NaMg)(□Al) –1 , and (Fe 2+ Fe 3+ )(MgAl) –1 substitution mechanisms. Different tourmaline compositions and substitution mechanisms could be used as guides for mineral exploration.

Skarn mineralogy and its geological significance for the Tayuan (Cu–Mo)–Pb–Zn deposit, northern Daxinganling metallogenic belt

The Tayuan (Cu–Mo)–Pb–Zn deposit is located in the northern part of Daxinganling, NE China. Lenticular ore body occurs in the skarn zone. The skarn minerals mainly include garnet, pyroxene, epidote and wollastonite. Electron microprobe analysis shows that the end member of garnet is mainly andradite (Ad62–97Gr11–45), the pyroxene is mainly diopside, and epidote is mainly clinozoisite. These characteristics indicate that the Tayuan polymetallic skarn deposit is mainly calcareous skarn. Sometimes the content zonation can be observed in garnets. With one garnet crystal, content is shifty from the core to the rim. In general, the iron content in the core is higher than in the edge. The content in the garnet shows that the garnet in the Tayuan deposit formed from weak oxidation in alkaline environment with the oxygen fugacity increasing, suggesting that the hydrothermal fluid evolved from an acidic to a slight alkaline state. In the Tayuan polymetallic deposit, the ratio of Mn/Fe in pyroxene is about 1.3, and of Mg/Fe, it is about 2. The components of garnet in the Tayuan deposit plot in the field of the typical skarn Zn, Cu, Mo deposits in the world.

Multistage amphiboles from the Galinge iron skarn deposit in Qiman Tagh, western China: evidence of igneous rocks replacement

Amphiboles from the Galinge skarn deposit, the largest iron (Fe) polymetallic skarn deposit in the Qiman Tagh metallogenic belt (western China), were formed by multistage fluid-rock interactions. Mineral analysis of the various amphiboles suggest that they were formed by the replacement of mafic to intermediate igneous rocks. The two alteration phases have formed three generations of compositionally distinct amphiboles: Amp-I: Ferro-edenitic hornblende (FE); Amp-II: Deep bluish-green magnesian-hastingsite (MH); Amp-III: Light greenish-beige ferro-actinolite (FA). The Amp-I preserves the primary igneous amphibole composition, and was subsequently replaced by Amp-II. The amphibole Cl content markedly increases from the FE (0.176 − 0.582 wt.%) to the MH (0.894 − 3.161 wt.%), and abruptly drops in the FA (0.017 − 0.039 wt.%). The Cl-rich MH contains the lowest concentration of Si [5.64 − 6.28 atoms per formula unit (apfu)], and the highest (K + Na) values (0.72 − 1.06 apfu) in the amphibole A-site with a high K/(K + Na) of 0.491 to 0.429. Both Mg and Fe contents of the MH and FA vary widely, possibly due to the interactions of magma-derived hydrothermal fluids with the basaltic / andesitic host rocks. Formation of the Cl-rich MH may have been associated with the early high-temperature and high-saline hydrothermal fluids, meanwhile the Cl-poor FA may have formed from later low-temperature and low-saline hydrothermal fluids. The MH plays an important role for consuming Cl carried by hydrothermal fluids. The Cl-rich fluids may have mobilized some elements, such as Fe, Al, Mg, Ca and Ti from the host rocks. Considerable amounts of Ti, Al, Mg and Fe were incorporated into the sphene and Fe-Ti oxides that coexist with the MH.

In-situ LA–ICP–MS trace elements analysis of magnetite: The Fenghuangshan Cu–Fe–Au deposit, Tongling, Eastern China

The Fenghuangshan deposit is a typical Cu–Fe–Au skarn deposit in the Tongling area, Anhui province, Eastern China. The deposit has a paragenetic sequence of a prograde skarn stage, followed by a retrograde skarn stage, and a final quartz–sulfide and carbonate stages. Magnetite in the Fenghuangshan deposit mainly formed in the retrograde and carbonate stages. According to the morphology of magnetite and mineral assemblage of ores, we divided magnetite-bearing ores into three groups. Group 1 (early retrograde skarn stage) is represented by a mineral assemblage of magnetite and chalcopyrite. Group 2 (late retrograde skarn stage) has a mineral assemblage of magnetite, chalcopyrite, and wollastonite with characteristic ring-like magnetite. Group 3 (carbonate stage) is characterized by large amounts of calcite veins crosscut or associated with magnetite and intensive hematization of magnetite crosscut by the veins.Laser ablation (LA)–ICP–MS was used to determine trace element concentrations of magnetite from the three mineralization stages. Positive correlations among Mg, Al, Ca, and Si in magnetite indicate that these lithophile elements have similar behavior during the skarn formation process. Calcium is an important discriminant element for magnetite in skarn deposits. Positive correlations are also evident for Pb, Sn and W in magnetite, which also indicates their similar behavior. In general, magnetite grains of different stages have similar normalized trace element patterns, indicating that they share a common source. However, some elements such as Co and Mn in magnetite decrease from early retrograde skarn stage, late retrograde skarn stage to carbonate stage, which may be attributed to the precipitation of coexisting minerals (sulfides and carbonates) or the decreasing temperature. Magnetite grains of the retrograde stage have higher Mg+Mn and Si+Al contents than those of the carbonate stage, indicating a decreasing degree of fluid–rock interaction during the skarn formation process. Trace element data of skarn magnetite indicate a more widely compositional variation than previously suggested. Magnetite from the Fenghuangshan Cu–Fe–Au deposit has similar composition to those from other Cu, Cu–Fe or Cu polymetallic skarn deposits, but different from those from Fe skarn deposits, such that magnetite composition is very powerful in establishing the origin of skarn deposits.

Skarn zonation and rock physical properties of the Wondong Fe-Pb-Zn polymetallic deposit, Korea

The Wondong Fe-Pb-Zn polymetallic skarn deposit is located in the Taebaeksan Basin, South Korea. This deposit is associated with the Paleocene quartz porphyry and characterized by abundant exoskarn and subordinate endoskarn. A general zonation pattern is developed comprising a proximal reddish-brown garnet-rich zone, a distal greenish garnet ± pyroxene zone, and a wollastonite-rich zone at the marble front. The mineralization is characterized by Fe in the proximal garnet-rich zone and Pb-Zn within and beyond the garnet ± pyroxene zone. In general, skarn deposits show complex geophysical signatures in their rock properties in relation to metasomatism. Garnet-rich and garnet ± pyroxene skarns accompanying Fe-oxides and sulfides are significantly denser (3.3–3.4 g/cm3) than the other rocks (2.5–3.0 g/cm3) such as quartz porphyry, wollastonite-rich skarn, and silicic hornfels. Reactions related to creating garnet may increase porosity, which promotes further infiltration and reaction to produce garnet growth. The porosity of skarn rocks (1.8–8.4%) has a broad range and is generally higher than the other rocks (0.8–3.3%). In contrast, most skarn rocks show a remarkably low electrical resistivity (mostly 211–848 Ωm) than the other rocks (1,815–8,601 Ωm). Magnetic susceptibilities of skarn rocks (15–140 × 10–5 SI) are higher than quartz porphyry and siliceous hornfels (<25 × 10–5 SI). P wave velocities in the garnet ± pyroxene zone at the skarn front show lower values (1,487–3,674 m/s) than the other rocks (2,902–5,590 m/s), which is likely related to the porosity of the rocks. Thus, in general, the physical properties of rocks as exampled above from the skarn environment reflect their mineral assemblages and can be used for mineral exploration of skarn deposits.

Ore genesis and hydrothermal evolution of the Huanggang skarn iron–tin polymetallic deposit, southern Great Xing'an Range: Evidence from fluid inclusions and isotope analyses

The southern Great Xing'an Range is one of the most important metallogenic belts in northern China, and contains numerous Pb–Zn–Ag–Cu–Sn–Fe–Mo deposits. The Huanggang iron–tin polymetallic skarn deposit is located in the Sn-polymetallic metallogenic sub-belt. Skarns and iron orebodies occur as lenses along the contact between granite plutons and the Lower Permian Huanggangliang Formation marble or Dashizhai Formation andesite. Field evidence and petrographic observations indicate that the three stages of hydrothermal activity, i.e., skarn, oxide and sulfide stages, all contributed to the formation of the Huanggang deposit.The skarn stage is characterized by the formation of garnet and pyroxene, and high-temperature, hypersaline hydrothermal fluids with isotopic compositions that are similar to those of typical magmatic fluids. These fluids most likely were generated by the separation of brine from a silicate melt instead of being a product of aqueous fluid immiscibility. The iron oxide stage coincides with the replacement of garnet and pyroxene by amphibole, chlorite, quartz and magnetite. The hydrothermal fluids of this stage are represented by L-type fluid inclusions that coexist with V-type inclusions with anomalously low δD values (approximately −100 to −116‰). The decrease in ore fluid δ18OH2O values with time coincides with marked decreases in the fluid salinity and temperature. Based on the fluid inclusion and stable isotopic data, the ore fluid evolved by boiling of the magmatic brine. The sulfide stage is characterized by the development of sphalerite, chalcopyrite, fluorite, and calcite veins, and these veins cut across the skarns and orebodies. The fluids during this stage are represented by inclusions with a variable but continuous sequence of salinities, mainly low-salinity inclusions. These fluids yield the lowest δ18OH2O values and moderate δD values ( −1.6 to −2.8‰ and −101 to −104‰, respectively). The data indicate that the sulfide stage fluids originated from the mixing of residual oxide-stage fluids with various amounts of meteoric water. Boiling occurred during this stage at low temperatures.The sulfur isotope (δ34S) values of the sulfides are in a narrow range of −6.70 to 4.50‰ (mean=−1.01‰), and the oxygen isotope (δ18O) values of the magnetite are in a narrow range of 0.1 to 3.4‰. Both of these sets of values suggest that the ore-forming fluid is of magmatic origin. The lead isotope compositions of the ore (206Pb/204Pb=18.252–18.345, 207Pb/204Pb=15.511–15.607, and 208Pb/204Pb=38.071–38.388) are consistent with those of K-feldspar granites (206Pb/204Pb=18.183–18.495, 207Pb/204Pb=15.448–15.602, 208Pb/204Pb=37.877–38.325), but significantly differ from those of Permian marble (206Pb/204Pb=18.367–18.449, 207Pb/204Pb=15.676–15.695, 208Pb/204Pb=38.469–38.465), which also suggests that the ore-forming fluid is of magmatic origin.

Identifying geochemical anomalies associated with Cu and Pb–Zn skarn mineralization using principal component analysis and spectrum–area fractal modeling in the Gangdese Belt, Tibet (China)

The Gangdese Belt is now recognized as an important Cu polymetallic mineralization belt. Recent studies suggest that apart from porphyry copper deposits, polymetallic skarn deposits are another significant deposit type in this belt. In this paper, principal component analysis (PCA) and spectrum–area ( S– A) fractal modeling are used to identify geochemical anomalies associated with Cu and Pb–Zn skarn mineralization based on Cu, Pb, Zn and Ag stream sediment data. Firstly, the raster maps of Cu, Pb, Zn and Ag were obtained by multifractal inverse distance weighted (MIDW). Secondly, PCA was used to combine the Cu, Pb, Zn and Ag concentration values. Finally, S– A analysis was used to decompose the first component pattern obtained by the PCA. The results show that major anomalies of Cu, Pb, Zn and Ag are mostly located around mapped intrusions, and along E–W trending faults, where Cu and Pb–Zn skarn deposits favorably occur. These results indicate that: (1) the Gangdese Belt potentially hosts undiscovered Cu and Pb–Zn skarn deposits, and the integrated anomalies for Cu, Pb, Zn and Ag occurring around the intrusions and in the vicinity of faults in the center part of the Gangdese Belt should be further investigated in the next step of mineral resource exploration; and (2) the hybrid method combining PCA and S– A modeling is an effective tool to identify geochemical anomalies.

Porphyry Cu–Au and associated polymetallic Fe–Cu–Au deposits in the Beiya Area, western Yunnan Province, south China

The Alkaline porphyries in the Beiya area are located east of the Jinshajiang suture, as part of a Cenozoic alkali-rich porphyry belt in western Yunnan. The main rock types include quartz-albite porphyry, quartz-K-feldspar porphyry and biotite–K-feldspar porphyry. These porphyries are characterised by high alkalinity [(K 2O + Na 2O)% > 10%], high silica (SiO 2% > 65%), high Sr (> 400 ppm) and 87Sr/ 86Sr (> 0.706)] ratio and were intruded at 65.5 Ma, between 25.5 to 32.5 Ma, and about 3.8 Ma, respectively. There are five main types of mineral deposits in the Beiya area: (1) porphyry Cu–Au deposits, (2) magmatic Fe–Au deposits, (3) sedimentary polymetallic deposits, (4) polymetallic skarn deposits, and (5) palaeoplacers associated with karsts. The porphyry Cu–Au and polymetallic skarn deposits are associated with quartz–albite porphyry bodies. The Fe–Au and polymetallic sedimentary deposits are part of an ore-forming system that produced considerable Au in the Beiya area, and are characterised by low concentrations of La, Ti, and Co, and high concentrations of Y, Yb, and Sc. The Cenozoic porphyries in western Yunnan display increased alkalinity away from the Triassic Jinshajiang suture. Distribution of both the porphyries and sedimentary deposits in the Beiya area are interpreted to be related to partial melting in a disjointed region between upper mantle lithosphere of the Yangtze Plate and Gondwana continent, and lie within a shear zone between buried Palaeo-Tethyan oceanic lithosphere and upper mantle lithosphere, caused by the subduction and collision of India and Asia.