Mineralized Granitic Porphyry of the Yangla Copper Deposit, Western Yunnan, China: Geochemistry of Fluid Inclusions and H-O, S, and Pb Isotopes

The Yangla copper deposit (YCD) is located in the central part of the Jinshajiang tectonic belt (Jinshajiang metallogenic belt) and is one of the most important copper deposits which has the large-scale copper reserves of the northwestern Yunnan, China. The ore bodies are strictly controlled by the stratum, pluton, and structure, which are layered, lens, and vein-like within the contact or fracture zone of the pluton and surrounding rock. At Yangla, two styles of mineralization occur at the brecciated contact zone between the pluton (granodiorite and granitic porphyry) and carbonaceous wall rock and include strata bound/lens-shaped replacement of carbonate rocks (skarn style) and porphyry-style sulfide-quart-calcite veins. But, the granitic porphyry mineralization have received less attention; the isotope and fluid inclusion studies are relatively scarce for limited porphyry ore bodies that have been discovered at the YCD. Quartz-hosted fluid inclusions from the recently discovered granitic porphyry have homogenization temperature averaging around 180 ± 20C and 300 ± 20C with salinities ranging from 4 to 22wt.% NaCleq, pointing toward the contribution of medium temperature-medium salinity and low temperature-low salinity fluids during the metallogenesis. These fluid inclusions have δOH2O values ranging between -1.91‰ and -1.02‰ and δD values ranging between -143.10‰ and -110‰, suggesting that the ore-forming fluid was a mix of magmatic and meteoric water. Ore-related pyrite/chalcopyrite have δSV-CDT values ranging from -1.0‰ to 1.0‰ and whole rocks have δ SΣS = 0.34, suggesting that sulfur mainly derived from magmatic rocks of the Yangla mining area. The sulfides Pb/Pb ranged from 38.8208-38.9969, Pb/Pb from 15.7079-15.7357, and Pb/Pb from 18.5363-18.7045, indicating that the lead mainly originated from the upper crust. It is demonstrated that the evolution of ore-forming fluid is continuous from the skarn ore body (SOB) stage to the porphyritic ore body stage and belong to the products of the same ore-forming fluid system, and the unisothermal mixing and cooling actions were maybe the main mechanism at the metallic minerals precipitation in mineralized granitic porphyry (MGP). A model is proposed according to the early stage, a magmatic fluid reacted and replaced with the surrounding carbonate rocks and then formed skarn-type ore bodies. The magmatic-hydrothermal fluid subsequently deposited porphyry-type quartz-calcite veins, veinlets, and stockwork mineralization.

As an important Cu producer in SW China, crystallization and ore-forming ages of the Yangla ore district attracted much attention, and the timing of granodiorite pluton and skarn ore bodies have been constrained to the Triassic (208-239 Ma, average 230 Ma) and Triassic (228-235 Ma, average 230 Ma) by the precise zircon U-Pb, biotite and hornblende Rb-Sr, and molybdenite Re-Os dating, respectively [9-12, 15-20, 22, 23]. These results have revealed the fact that skarn ore bodies was basically contemporary with granodiorite pluton in the YCD. Besides, for the YCD, the H-O isotopic composition of quartz was interpreted to be derived from the mixing of magmatic and meteoric water in skarn ore bodies [9-12, 24, 25, 27, 28, 30]. The sulfur isotopic signature of ore-related sulfides was interpreted to originate from the magmatic rocks (granodiorite pluton) of the Yangla region [9-12, 19, 24, 25, 27, 31] and that of lead is believed to have resulted from the mixing of mantle crustal materials in skarn ore bodies [9-12, 17, 19, 25-27, 29, 32-34]. So far, however, no systematic studies of the porphyry plutons of YCD and only preliminary studies have been conducted on the geochemical characteristics of the granitic porphyry dike [35]. So, the genetic relationships between porphyry plutons and Cu mineralization, origin and evolution of the deposit, and the metallogenic processes involved remain unclear. In recent years, a granitic porphyry dike closely associated with Cu mineralization was discovered at the tunnel 3250 m level in the process of geological prospecting in Yunnan Copper Industry (Group) Co. Ltd., 2014, which are suggesting the potential contribution of porphyry plutons to the Cu deposits at depth.
In this study, we present a study of fluid inclusions and stable (H-O-S) and radiogenic (Pb) isotope systematics of the MGP, YCD. The fluid inclusion results combined with isotopic data provide clear constraints in particular to explain the origin, evolution, and mechanisms of the ore-forming fluids. We hope that this study can provide a scientific basis for further mineral prospecting and future prospecting of new Cu deposits in this area.

Geological Context
2.1. Geologic Setting. The "Sanjiang" metallogenic belt (Sanjiang: Jinshajiang, Langcanjiang, and Nujiang) is located at the southwest edge of Yangtze craton, southwest China (Figure 1(a)). The large-scale Yangla copper ore region is located in the paleo-Tethyan orogenic belt of the central Sanjiang region (Figure 1(b)), clamped between the regional Jinshajiang and Yangla faults, which have an approximately N-S orientation (Figure 1(c)). In this region, the base of the Yangtze continental plate has experienced multiple geologic transformations due to extension, rift sag, subduction, and collision, which have resulted in the formation of multiple arc-basins [28,32]. The Jinshajiang paleo-Tethyan tectonic belt began rifting during the late Devonian, expanding into the Carboniferous-Permian basin (360-252 Ma). During the late stages of the early Permian, the Jinshajiang ocean basin was subducted to the west beneath the Changdu-Simao block . Because of an E-W trend compression/squeezing action, a series of low-angle thrust faults oriented toward the northwest was formed in the Jinshajiang belt [9][10][11][12]. At the same time, the subduction of the Jinshajiang ocean basin resulted in partial melting of the lower crust, forming large amounts of intermediate-to-evolved magma, large-scale volcanic and magmatic activity [9-12, 19, 24, 28], and granodioritic magmatism at 208-239 Ma, average 230 Ma [9-12, 16, 19, 32, 34]. Continued subduction also metasomatized and fertilized the mantle wedge and may also have led to the accumulation of a free volatile phase in the mantle wedge [9-12, 16, 32]. During the early Late Triassic (252-228 Ma), the tectonic environment transitioned from compressive to extensional tectonics, allowing the continuous upward migration of magmatic fluid and promotion of ore migration [32,34]. It is believed that when the magmatic fluid within the mantle wedge reached the bottom of the early granodiorite pluton, the board-shaped or plate-shaped granodiorite pluton obstructed the upward migration and emplacement of the late-stage magmatic fluid [24,32,34]. The magmatic fluid was enriched in ore elements either in the reverse fault system of this early pluton or after migrating along rock fissures by infiltrating and metasomatizing carbonate rocks [9][10][11][12]16]. The YCD thus appears to have formed during the early Late Triassic (252-228 Ma). Moreover, the tectonic background of the Jinshajiang tectonic belt involved large-scale magmatic fluid activity caused by the transition from compressive to extensional tectonics [9-12, 16, 19, 25, 27].
The mining camp is characterized by a strong strctural control. In addition to the Jinshajiang and the Yangla faults, F4 faults run in the NE direction and a large number of interlayer fracture zones and secondary structural fractures have also developed [6,32]. Regional faults control the spatial distribution of plutons and ore bodies, while NE-trending faults cause the plutons and ore bodies to fracture, forming various ore blocks and plutons. The contacts between the magmatic intrusions and the surrounding wall rock control the morphology of skarn ore bodies that are close to the contact zone. Interlayer faults control the morphology of stratiform ore bodies, fissures within plutons control the morphology of vein-type ore bodies, and fissures at the top and the boundaries of plutons are usually filled with quartz-sulfide veinlets. The late-stage NE-trending faults control the morphology of late-stage hydrothermal vein deposits [6].
Magmatic rocks are widely distributed within the mining camp. Extrusive rocks, intrusive rocks, and dyke rocks all have developed. Extrusive rocks mainly consist of andesites and basalts (362 Ma and 296 Ma) (Table 1, Figure 2) and appear to have little association with ore formation [21]. Intrusive rocks were mainly formed during the Indosinian Period (208-239 Ma, and it is concentrated between 227 and 238 Ma, with an average 230 Ma) (Table 1, Figure 2) are mainly granodiorites and are spatially related to the ore deposits. From north to south, the intrusive rocks can be divided into the Beiwu, Linong, Lunong, and Jiaren plutons.
Based on the different ore-hosting rock types, the YCD ores can be divided into 4 types: skarn, hornfels, porphyry, and veins [8,36]. The skarn-type ore bodies are mainly distributed in the Linong ore block, with the most typical KT2 (main ore body) and KT5 ore bodies (Figure 3), and its    Figure 2) [9-12, 16, 17, 19, 23]. The hornfel-type ore bodies are mainly distributed in the Linong and Lunong ore blocks and the hydrothermal vein-type ore bodies are mainly distributed in the Linong, Jiangbian, Tongjige, and Jiaren ore blocks. The copper ore bodies of the Linong block mainly occur in the outer contact zone between the pluton and the surrounding rock. It has a variably stratified or vein-like structure and is obviously controlled by the interlayer fracture zone. The copper ore bodies of the Lunong, Tongjige, and Jiaren ore blocks occur within the pluton and the surrounding rock and in the outer contact zone between them. Their morphology is controlled by the contact zone [34]. The upper and lower interface of the ore bodies are composed of quartzite, marble, and sericite sandy slate. The ore body is inclined toward the west with a 20-30°dip angle, and it is obviously controlled by the regional tectonic structure ( Figure 3). The alteration-mineralization are mainly chalcopyrite, pyrite, pyrrhotite, galena, sphalerite, and mala-chite. Copper ores are associated with Pb, Zn, Ag, Au, As, Mo, and Sb [16]. The ore minerals are mainly chalcopyrite, pyrite, pyrrhotite, and a small amount of bornite, galena, molybdenum, sphalerite, malachite, and covellite. The gangue minerals include quartz, calcite, biotite, plagioclase, diopside, tremolite, chlorite, and garnet. The ore textures include euhedral and anhedral, metasomatic, porphyroblastic/porphyritic, crushed, and interstitial. The ore structures can be massive, disseminated, stockwork, banded, and lumpy in SOB [4,[8][9][10][11][12]].
2.3. Characteristics of the MGP. The porphyry pluton was first found as an irregular outcrop in the Linong ore block, YCD. The stock-shaped outcrop intrudes into the Linong sericite sandy slate and quartzite [35]. The contact zones host small amounts of pyrite, galena, and magnetite. This porphyritic pluton is spatially related to the KT1 ore body of the Linong ore block, and it has been inferred to be genetically related to the porphyritic copper mineralization [35].    Zone I: carbonatation, silicification, argillization, sericitization, and weak pyritization. Zone II: skarnization, pyritization, chalcopyritization, silicification, and carbonatation. Zone III: the mineralized granite porphyry dike with strong silicification, as well as calcitization, pyritization, chalcopyritization, molybdenitization, sericitization, and chloritization. Zone IV: silicification, pyritization, sericitization, and chloritization. The mineralization-alteration characteristics are similar to those of the typical porphyry Cu deposits.
The MGP (porphyry ores) shows a veined, banded, and massive structure (  . Sphalerite intersected and replaced chalcopyrite and pyrite, indicating that sphalerite was formed later than chalcopyrite and pyrite (Figure 7(r)). Thus, the mineral paragentic associatons can be summarized as pyrite→chalco-pyrite→sphalerite within the quartz veins in the hydrothermal mineralization periods and the mineral assemblage were mainly quartz-pyrite-chalcopyrite-sphalerite.
To sum up, based on the observation of macroscopic and microscopic characteristics of the minerals in the MGP samples ( Figures 6 and 7), diagenesis-mineralization can be divided into three stages from diagenesis to hydrothermal mineralization, such as (i) the diagenesis stage and quartz, plagioclase, and biotite phenocryst crystallized out of granitoid magma and formed granite porphyry; (ii) quartz-sulfide stage, forming a large number of quartz-sulfide veins (quartz, pyrite, chalcopyrite, sphalerite, bornite, etc.) and representing hydrothermal mineralization and forming porphyry (mineralization) ore bodies within the granite porphyry (pluton); and (iii) the calcite stage, the formation of a large number of nonmetallic mineralization of calcite veins, representing the hydrothermal mineralization has ended.

Materials and Methods
The MGP samples used for the analyses of fluid inclusions and H-O-S-Pb isotopes were obtained from the tunnel

Metamorphic quartz sandstone
Low-grade skarn ore body  The sericite slate, which developed the later quartz veins, disseminated-fine vein metal sulfides. Zone I: carbonatation, silicification, argillization, sericitization, and weak pyritization. Zone II: skarnization, pyritization, chalcopyritization, silicification, and carbonatation. Zone III: the mineralized granite porphyry dike with strong silicification, as well as calcitization, pyritization, chalcopyritization, molybdenitization, sericitization, and chloritization. Zone IV: silicification, pyritization, sericitization, and chloritization.  8 Geofluids 3250 m level of the 41 mine, Linong ore block, YCD. Some quartz-sulfide ores that precipitated during the stage of hydrothermal mineralization were collected from the Linong ore block for fluid inclusions and detailed isotope analysis. From these ores, 11 and 4 ore-bearing quartz samples were collected for fluid inclusions and oxygen and hydrogen isotope analyses, respectively. 10 and 13 sulfide samples were collected for sulfur and lead isotope analysis. The microthermometric and Laser Raman analyses of the fluid inclusions were performed at the fluid inclusion laboratory of the Kunming University of Science and Technology. The analyses were conducted using a Linkam THMS600 heating/freezing stage. The testing temperature ranged from -196 to 600°C, with a homogenization temperature measurement error of ±2°C and an ice melting temperature measurement error of ±0.2°C. The heating and the cooling rates began at 30°C/min and were reduced to both 1°C/min and 0.5°C/min close to the phase transition point. Each inclusion sample was subjected to heating and freezing, and in each scenario, each sample was measured twice or more to check the precision of the temperature measurements and to ensure that no leaks had occurred. A Renishaw 2000 Raman Imaging Microscope was used for Laser Raman analyses. The laser has a wavelength of 514.53 nm with a power of 20 mW, a minimum laser beam spot diameter of 1 μm, and a spectral resolution of 1-2 cm -1 .
The petrography and temperature measurements of fluid inclusions were conducted in quartz. At room temperature, the fluid inclusions were mostly gas-liquid two-phase inclusions, followed by monophase liquid inclusions ( Figure 9). Primary inclusions exhibited strip-like, elliptical, spherical, and irregular shapes, with variably scattered and dense distributions. In some areas, visible secondary fluid inclusions, 10 Geofluids mainly with strip-like, elliptical, spherical, and irregular morphologies, assumed linear distributions along fractures. In this study, all of the measured fluid inclusions were of primary phases. The primary inclusions were of two types: (1) enriched liquid-phase inclusions (V-L), which constituted~96% of the total number of inclusions. At room temperature, a gasliquid two-phase composition was observed (Figures 9(a)-9(f)). Their size ranged from 4-12 μm, with most having between 4 and 7 μm diameter. Morphologies were most often elliptical, spherical, strip-like, and irregular. Inclusions were heated uniformly until they reached a liquid phase (2), monophase liquid inclusions (L), which constituted 4% of the total number of inclusions. The inclusion ranged in size from 4 to 6 μm, with small sizes being more common. Most inclusions were elliptical or irregular in shape (Figures 9(a)-9(c)).

H-O Isotopes.
Analyses of hydrogen and oxygen isotopes in quartz (hydrothermal) were completed at the Laboratory of Isotope Geology of the Institute of Geology of the Chinese Academy of Geological Sciences. Hydrogen and oxygen isotopes of quartz were analyzed using a Finningan MAT 253 mass spectrometer. The sample preparation process is as follows: firstly, the samples are broken and pure quartz particles (40 mesh) are selected by handpicking under binocular microscope, and the quartz particles are crushed into powder. The conventional BrF 5 method was used for oxygen isotope analysis of quartz, and BrF 5 was used to react with oxygen-containing minerals in vacuum and high temperature to extract mineral oxygen, which was then burned with a hot resistance-graphite and converted into CO 2 gas [37]. Hydrogen isotopes of quartz inclusions were opened by vacuum thermal explosion method, the water was obtained by separation, and water was reacted with zinc to obtain H 2 gas for mass spectrometry [38]. The oxygen isotopes and inclusion hydrogen isotope analysis of quartz determination precision were ± 2‰, and the analytical results were reported relative to the SMOW ("Standard Mean Ocean Water") standard.
3.3. S Isotopes. Sulfur isotope analyses were conducted at the Laboratory of Isotope Geology of the Institute of Geology of the Chinese Academy of Geological Sciences. The sulfidebearing rock samples were mechanically crushed and the pyrite and chalcopyrite were separated by handpicking under the microscope. Single grains of pyrite and chalcopyrite were mixed with copper oxide (CuO), heated and oxidized, and

Geofluids
formed SO 2 gas. The generated SO 2 gas was frozen and extracted using the method of liquid nitrogen. The sulfur isotope composition was analyzed by the collected SO 2 gas using a MAT 251 Mass Spectrometer. The results are reported with respect to the V-CDT standard with a precision of ±0.2‰.

Pb
Isotopes. Lead isotope analyses were performed at the Laboratory of Isotope Geology of the Institute of Geology of the Chinese Academy of Geological Sciences. The Pb separation and purification was achieved using used AG1-X8 anion exchange resin. The analyses were performed using a Nu Plasma HR high-resolution multicollector inductively coupled plasma mass spectrometer. The mass fractionation of the instrument was externally corrected using about one-half the lead content of the samples of T1 isotope standard [39].   [17,[24][25][26]. 13 Geofluids inclusion density was determined from homogenization temperature-salinity-density phase diagrams ( Figure 10) and the entrapment pressure was estimated from homogenization temperature-salinity-pressure phase diagram in the H 2 O-NaCl system [24,[41][42][43].
For fluid inclusions of the second group, the variation in T m ranged from -18°C to -10°C (average -13°C) and T h ranged from 283°C to 316°C and was mainly concentrated between 280°C and 320°C (average 300°C). The salinity ranged from 14 to 21 wt.% NaCl eq (average 17 wt%.  14 Geofluids  NaCl eq ). Based on the density and isochoric formula for the NaCl-H 2 O system [45][46][47], the density ranged from 0.85 to 0.95 g/cm -3 with an average of 0.89 g/cm -3 (Figure 12(a)). A range of trapping pressures ranging from 50 to 100 bars was calculated, with an average of 80 bars (Figure 13(a)).

Pb Isotopic Compositions.
The lead isotopic composition of pyrite and chalcopyrite from the MGP and the SOB was also assessed (  18.28). The characteristic parameters for the skarn ore bodies were μ = 9:18 to 9.70, ω = 34:61 to 39.39, and Th/U = 3:65 to 3.91. The lead isotopic ratio of sulfides in the MGP were lower and more uniform than that of sulfides in SOB.  (Figure 15(b)). Meanwhile, the MGP was located in the region between the meteoric water and the magmatic water, and its δD and δ 18 O H2O values were lower than those of the SOB (garnet-quartz). This maybe because the carbonate replacement formed by SOB was a high-temperature magmatic hydrothermal fluid, at this moment, allowing only a few of meteoric water to infiltrate ore-forming fluid, resulting in the δD-δ 18 O H2O diagram appearing closer to the magmatic water. Along the continuous evolution of ore-forming fluid, the amount of infiltrating meteoric water increased, forming low-temperature oreforming fluid, and which may make the metallogenic temperature decrease (the homogenization temperatures of fluid inclusions have decreased), which will make the δD and δ 18 O H2O values decrease. Finally, the δD and δ 18 O H2O values show a trend line away from magmatic water or near meteoric water from SOB to MGP (Figure 15(b)), and we believe that the ore-forming fluid originated from the mixture of magmatic water and meteoric water. According the Re-Os age of molybdenite in SOB (228-235 Ma) and the evolution trend of ore-forming fluid, SOB were formed during the early-stage metasomatic interaction with carbonates [15,16,34,49], while porphyry ore bodies were formed during the late stage. The geological evidence are as follows: (i) the ore-forming fluid shows the evolution trend of high temperature-high salinity-high capture pressure to low temperature-low salinity-low capture pressure from SOB to porphyry ore bodies (MGP),and there is an overlap region; (ii) the hydrogen and oxygen isotope composition shows that the SOB→porphyry ore bodies (MGP) have a tendency to be close to meteoric water. It is speculated that the mixing amount of meteoric water gradually increased and finally formed porphyry ore-bodies along with the evolution of ore-forming fluid. Therefore, the skarn and porphyry 19 Geofluids ore bodies were maybe the products of continuous evolution in the same magmatic fluid system and formed in different stages.

Discussion
The determination of sulfur element sources in deposits must be based on the total sulfur isotopic composition (δ 34 S ΣS ) in the ore-forming hydrothermal fluid during sulfide precipitation. Experimental studies show (Zheng et al. 2000) that the hydrothermal system 34 S order is SO 4 2- under the condition of isotope exchange equilibrium. Therefore, based on the theory of equilibrium crystallization of sulfur isotopes in solution, when sulfur isotopic fractionation reaches equilibrium conditions, the sequence of the enriched δ 34 S is as follows: δ 34 S sulfate >>δ 34 S molybdenite > δ 34 S pyrite > δ 34 S sphalerite > δ 34 S pyrrhotite > δ 34 S chalcopyrite > δ 34 S galena > δ 34 S chalcocite > δ 34 S argentite > δ 34 S cinnabar , when sulfur fractionation reaches equilibrium conditions, the pyrite and pyrrhotite δ 34 S values can represent the total sulfur (δ 34 S ΣS ) in the ore-forming fluid [50,51]. Out of the 5 tested samples, only the YS-3 sample exhibited δ 34 S pyrite > δ 34 S chalcopyrite , with the sulfur fractionation process reaching equilibrium conditions, while the remaining 4 samples exhibited δ 34 S chalcopyrite > δ 34 S pyrite , with the sulfur fractionation not reaching equilibrium conditions. But, the δ 34 S has a sequence of mineral enrichment for most  (Table 4). Based on the δ 34 S sequence of minerals enrichment for most sulfide samples in this deposit (the sample YS-3 and most of the SOB sulfide samples), we concluded that the hydrogen sulfide (H 2 S) in the ore-forming system during the ore-forming period practically reached equilibrium [19,24]. Therefore, the total sulfur isotopic composition (δ 34 S ΣS ) can be determined using the following two methods.

Sulfur-Bearing Mineral Assemblage Estimated δ 34 S ΣS .
Sulfide compounds in the Linong ore block of the YCD have simple compositions and do not contain sulfate minerals. They are mainly composed of pyrrhotite, pyrite, chalcopyrite, molybdenite, and sphalerite. Its main soluble form is H 2 S, which is a reductive fluid with pH > 6 [28]. The average value of sulfide δ 34 S, especially the pyrite δ 34 S value, can approximately represent the total sulfur δ 34 S ΣS [51] in the hydrothermal fluid. In addition, the sulfur isotope value is a function of    23 Geofluids pH, temperature, Eh and oxygen fugacity, and it is influenced significantly by physical and chemical conditions [52]. It is possible that the varying chemical and physical conditions during different stages of mineralization and superimposed mineralization may have led to nonequilibrium fractionation of sulfur isotopes in sulfides. This conclusion is consistent with the composite formation of the ore deposit. In the MGP of theYCD, the sulfide δ 34 S V-CDT variation range being concentrated between -1.0‰ and 1.0‰, the pyrite δ 34 S V-CDT values were concentrated between 1 and -7‰, and the chalcopyrite δ 34 S V-CDT values were concentrated between 1 and 0‰ (Figure 16(a)). This is consistent with the research results on the sulfur isotopic composition of sulfides in SOB (the δ 34 S V-CDT values range from -5‰ to 3‰, with an average of -0.30‰ and a difference of 8‰; where the pyrite δ 34 S V-CDT values range from -3‰ to 3‰, with an average of -0.50‰ and a difference of 6‰; the chalcopyrite δ 34 S V-CDT values range from -5‰ to 3‰, with an average of -1‰ and a difference of 8‰; the pyrrhotite δ 34 S V-CDT values range from -3‰ to 1‰, with an average of -1.25‰ and a difference of 4‰; the galena δ 34 S V-CDT values range of -1‰ to 3‰, with an average of 0.34‰ and a difference of 4‰; the sphalerite δ 34 S V-CDT values range from 1‰ to 2‰, with an average of 1.43‰ and a difference of 1‰; the molybdenite δ 34 S V-CDT values range from 0‰ to 1‰, with an average of 0.69‰ and a difference of 1‰; the chalcocite δ 34 S V-CDT values range from 1‰ to 2‰, with an average of 1.50‰ and a difference of 1‰) (Tables 4 and 6, Figure 16(b)). The total sulfur isotopic composition was close to -1‰ to 1‰, while its total homogenization was high and the variation range was small. Moreover, it had a single source of sulfur. All of these characteristics point to deep crust or mantle sulfur, indicating that the sulfur source of the MGP and the SOB was the same, originating in the deep crust-mantle magma. Moreover, the sulfur source was relatively solitary and without contamination by upper crust sediments.

Isotope Diagram Method
Estimation of δ 34 S ΣS . This method, also known as the Pinckney method [53], is based on the assumption that when ore-forming fluid isotopes reach equilibrium, the sulfur isotopic composition of the mineral can be considered a function of the temperature and the total sulfur isotopic composition of the ore-forming fluid, that is 1000 ln α x−y = A * 10 6 /T 2 + B, where 1000 ln α = δ 34 S mineral 1 − δ 34 S mineral 2 , B = 0. It is evident that at high temperatures, the δ 34 S values of each sulfide in the oreforming fluid are close to the δ 34 S ΣS values. If more than two minerals are crystallized from chemically and isotopically homogeneous ore-forming fluid with varying temperature, the sample should approximate a straight line on the 1000lnα x-y versus the δ 34 S x and δ 34 S y diagram. The δ 34 S-axis intercept is the δ 34 S ΣS values of the ore-forming fluid. Through interpolation, we determined the pyritechalcopyrite (belonging to the one ore-forming fluid) content in the MGP to be δ 34 S ΣS pyrite−chalcopyrite = 0:34‰ (Figure 17 [54], which reflects the tectonic setting of the lead source region, and the lead isotope data fell close to the upper crust evolutionary line on the 207 Pb/ 204 Pb-206 Pb/ 204 Pb diagram (Figure 18(a)) and between the orogenic zone and the lower crust evolutionary lines on the 208 Pb/ 204 Pb-206 / 204 Pb diagram, being closer to the former (Figure 18(b)). This is consistent with the geological background of the Jinshajiang ocean basin westward subduction and collisional orogenic with Changdu-Simao block, indicating that the lead source was the upper crust. The lead isotope relative variogram Δγ − Δβ is projected onto the Δγ − Δβ genetic classification diagram [55] (Figure 19(a)). The lead isotope composition mainly falls within the range of upper crust lead, which is dominantly consistent with the distribution of the lead source on the tectonic evolution diagram (Figure 17 (Figures 18 and 19(b)). But the lead isotopic composition of MGP was more stable and homogeneous than that of SOB, and its evolutionary range was narrower and shows a upper crust source (Figures 17 and 18(a)). The difference of Pb isotope source region in MGP and SOB may be the gradually blend of upper crust sediments during the mantle magmatic fluid evolution process. According to the results of fluid inclusion, the ore-forming fluids show an evolutionary trend from high temperature-high salinityhigh capture pressure to low temperature-low salinity-low capture pressure from skarn metallogenic stage to porphyry metallogenic stage. It means that there may be upper crust sediments added in the evolution process of ore-forming fluid, which makes it present the high to low level evolution trend. So, the evolution process of the magmatic fluid may be as follows: in the early stage of evolution process, the amount of upper crust sediments were less and formed SOB, and the mixing amount of upper crust sediments gradually increased along with the progress of mineralization. In the late stage, the magmatic fluid already have contained a large amount of upper crust sediments, which made the lead mainly derived from the upper crust in MGP phenomenon. Finally, the lead was mainly derived from the crust-mantle and upper crust in the SOB and MGP, respectively.

Evolution of Ore-Forming Fluid.
According to the temperature measurement results of fluid inclusions in garnet, epidote, and pyroxene, they show that the ore-forming fluid of skarn stage has high temperature and high salinity characteristics (Figures 10-12) [24,25,27]. Next, the research results of fluid inclusions in quartz indicates that the coexistence of low temperature medium-to-high salinity and medium temperatur-to-high salinity and the results of fluid inclusions in calcite indicate that ore-forming fluid in the calcite-sulfide stage has the characteristics of low temperature and low salinity ( Figure 12) [24,25,27]. In short, from the early skarn stage to the late calcite-sulfide stage, the homogenization temperature and salinity of the oreforming fluid has obviously decreased, and the homogeneous temperature and salinity of the adjacent stages have overlap regions, which show that the ore-forming fluid is continuous evolution [17, 24-27, 29, 32, 56, 57]. As the fluid inclusions developed in quartz of MGP, the homogenization temperatures are mainly concentrated between 120°C-200°C and 280°C-320°C, compared with the previous research results of fluid inclusions developed in quartz of SOB, there are overlap regions (Figures 10-13). Generally speaking, the homogenization temperatures of fluid inclusions from SOB to MGP present a trend from high to low level (420°C-220°C→200°C-120°C), namely, the homogenization temperature of Th MGP ≤ Th SOB, besides, the salinity of S MGP ≤ S SOB , the density of D MGP ≤ D SOB , and the overall trapping pressure of P MGP < P SOB (Figures 10-13). It maybe during the early stage that the magmatic fluid had high temperature, high pressure, high salinity, and low density at this moment, and the magmatic fluid metasomatic interaction with carbonates and formed SOB. Next, as the magmatic fluid continued to evolution, and meteoric water infiltrated, the temperature dropped, followed the suddenly release of pressure caused by fracturing, and hydraulic cracking action, which caused ore-forming fluid trapping pressure and density to decrease. The sedimentary materials of upper crust may contribute to some metallic elements and oreforming fluid replaced interaction with the early-formed skarn metal minerals, which make the ore-forming fluid salinity and density relatively decreased [25,27,28]. Hence, the ore-forming fluid has the feature of low temperature, relatively low pressure, relative low salinity, and low density at the late stage. Therefore, according the results of fluid inclusions in quartz of MGP and garnet, epidote, pyroxene, and quartz in SOB, we believe that the evolution of ore-forming fluid is continuous from SOB to MGP, and there may be products that belong to the same ore-forming fluid system.

Geofluids
But, in the skarn stage, the ore-forming fluid boiling action may be the main mechanism of metallic mineral precipitation in the YCD [17,19,24,25,27,28] Figure 19: Δγ-Δβ diagrams of the Pb isotopes from MGP (a) and SOB (b), YCD, Yunnan, China (after [55]). 1-mantle lead, 2-supracrustal lead, 3-mixed supracrustal and mantle lead (3a-magmatism, 3b-sedimentation), 4-chemical deposit lead, 5-submarine hydrothermal lead, 6-medium-high metamorphic lead, 7-high metamorphic lower crust lead, 8-orogenic belt lead, 9-ancient shales supracrustal lead, and 10-retrograde metamorphic lead. Δγ and Δβ represent the relative deviation from the same age mantle, Δβ = ½β/β M ðtÞ − 1 × 1000,Δγ = ½γ/γ M ðtÞ − 1 × 1000, β and γ are the measured values, β M (t) and γ M (t) are the mantle values at t time (t, the ages of the rocks at that periods). 28 Geofluids air bubbles after heating up to the homogeneous temperature of some gas-liquid fluid inclusions with medium gas-phase fraction (40%-60%), and it shows that the captured heterogeneous fluid phases are composed of gas and liquid phases in boiling state ( [25,27,28]; (iii) there are two kinds of primary fluid inclusions (gas-liquid and NaCl-bearing fluid inclusions) with different chemical properties, which have different salinity but similar homogenization temperature, and it shows that they were captured from two different kinds of fluids [25,27,28]; (iv) the explosive breccia is developed at the edge and part of the region of the plutons [25,27,28].
According to the evolution of ore-forming fluid which is continuous from SOB to MGP and belongs to the products of the same ore-forming fluid system, we believe that in the late stage (porphyritic stage) ore-forming fluid unisothermal mixing and cooling actions may happen ( Figure 12). Mineralization process under the unisothermal mixing and cooling actions of medium temperature-medium salinity and low temperature-low salinity ore-forming fluid may exist ( Figure 12) [19,24], and we believe that unisothermal mixing and cooling actions were the main mechanisms at the metallic mineral precipitation in MGP. The unisothermal mixing and cooling actions can cause the dissipation of the volatile components (including CO 2 , H 2 O, and H 2 S), which disrupted the physical and chemical balance of the oreforming fluid system, causing the precipitation of metallic minerals, such as pyrrhotite, chalcopyrite, pyrite, and bornite [17,19,25,27,28]. As the temperature and pressure continued to decrease, pyrite, chalcopyrite, bornite, sphalerite, quartz, and calcite were separated in the magmatic fluid [17,19,24,28] and mineralized in the granitic porphyry, meaning that late-stage magmatic fluid formed the porphyritic ore bodies.  [18,[58][59][60][61][62][63][64][65].The late-stage collision dynamic background caused the upwelling and underplating of the mantle magma, which was closely associated with the mineralization process at the Yangla region [1, 2, 9-12, 16, 25, 27, 30, 49]. The crustal material melted partially forming felsic magma and mixed in the deep magmatic chamber with the mantle-derived magma, forming a mixed parent magma. Then, after undergoing a degree of fractionation, the parent magma formed the granodiorite pluton of the Beiwu, Jiangbian, Linong, and Lunong mining areas. The zircon U-Pb ages of the granodiorite plutons are estimated at 208 Ma-239 Ma (it is mainly concentrated between 227 Ma and 238 Ma) with an average of 230 Ma [15,16,[18][19][20]22], and the Re-Os age of molybdenite in the SOB at 228-235 Ma, average 230 Ma [9-12, 16, 17, 19, 23], which indicates granodiorite pluton and SOB were produced at the same time. Studies have also shown that there is a continuous granitic magma activity in the Yangla region, with a duration of about 15-24 Ma [18], even 33 Ma [66], and combination with the evolution of oreforming fluid is continuous, and SOB and MGP may be belong to the products of the same ore-forming fluid system. Therefore, we believe that mineralization is continu-ous from SOB (early stage) to MGP (late stage) in the YCD. The S and Pb isotopic components of the MGP reveal that the source of the ore-forming materials was a mixed mantle-crust magmatic fluid, which is in basic accordance with the SOB ore-forming source [16-18, 25, 27, 28, 31, 32, 49]. The H-O isotopic composition of MGP reveals that the source of the ore-forming materials is a mixture of magmatic and meteoric water, which is consistent with the source of SOB [25-27, 29, 30]. The combination of mineralized geology background and the characteristics of fluid inclusions and the H-O, S, and Pb isotopic composition indicates that the metallic minerals in MGP and SOB are products of the same magmatic-meteoric fluid system. Their metallogenic process may have been as follows: in the early stage, hightemperature and high-pressure magma upwelled into the surrounding rock, and after contact metasomatism of carbonates, formed layered and stratified skarn-type and hornfeltype ore bodies in the outer contact zone between the granodiorite pluton and the carbonates; during the late stage, following the continuous crystallization of magma and the persistent meteoric-water infiltration, a mixture of magmatic and meteoric water was formed, followed by the formation of the porphyry-type ore bodies. At the same time, some residual magma migrated along the structural fractures of the  Figure 20: The simple diagram of metallogenic model of the granitic porphyry and granodiorite, YCD, Yunnan, China. 1-granodiorite, 2-granitic porphyry, 3-SOB, 4-porphyry-type ore-bodies, 5-hornfels ore bodies, and 6-veins ore bodies. 29 Geofluids overlying rock formations, and after the infiltrationmetasomatism process, it cooled and crystallized forming granite porphyry and the hydrothermal fluids form veinlike ore bodies in granite porphyry ( Figure 20).

Conclusions
The MGP exhibits dike-type intrusions in the Linong formation, and the overall occurrence have a strike of 60°NE and a steep dip of 40°NW. It is gray and has a porphyritic texture and a massive structure. Its phenocryst components are quartz, plagioclase, and biotite, and its matrix is felsic. A large number of quartz-calcite veins and veinlets, and disseminated pyrite, chalcopyrite, and a small amount of sphalerite have developed in the granitic porphyry pluton, indicating that there is potential for porphyry-type ore bodies in the deep part of the YCD.
The fluid inclusions developed in quartz of MGP indicates that the evolution of ore-forming fluid is continuous from SOB to MGP, and there may belong to the products of the same ore-forming fluid system. There may exist a medium temperature-medium salinity and low temperature-low salinity ore-forming fluid, and the ore-forming fluid unisothermal mixing and cooling actions are may the main mechanism of metallic minerals precipitation in MGP. The H-O isotopic composition shows that the main source of the ore-forming fluid was a gradually evolving mixture of magmatic and meteoric water. The S isotope composition reveals that sulfur originated from the magmatic rocks; the Pb isotope composition showed that the source of lead was the upper crust.
The porphyry-type ore bodies in the granitic porphyry and the skarn-type ore bodies of the YCD most likely belong to the same magmatic fluid system. During the early stage of evolution, the metasomatic interaction of the magmatic fluid and carbonate resulted in forming skarn-type ore bodies, while in the late stage, porphyry-type ore bodies were formed.

Data Availability
The data used to support the findings of this study are available from the corresponding author upon request.

Conflicts of Interest
The authors declare that they have no conflicts of interest.