Method for evaluating metallogenic potential of porphyry copper-(gold-molybdenum) ore

Abstract

The invention discloses a method for evaluating the mineralization potential of porphyry copper-(gold-molybdenum) ore. The evaluation method comprises the following steps: determining candidate rock masses with relatively high mineralization potential according to an oxygen fugacity value of magma zircon and / or a magma water content value of hornblende in a rock sample in an evaluation area; the aluminum saturation index ASI of the candidate rock mass is measured and calculated, the distribution coefficient and the distribution coefficient ratio of Cu, Au and Mo between fluid and melt are determined according to the ASI, simulation calculation is conducted through a Rayleigh fractionation model according to the distribution coefficient and / or the distribution coefficient ratio, and the content ratio of Au to Cu to Mo to Cu of the candidate ore body is obtained. According to the method, the mineralization potential of the porphyry copper ore and the enrichment degree and grade of Cu, Au and Mo of potential ore bodies can be rapidly and accurately evaluated.

Description

Technical Field

[0001] The present invention relates to the technical field of metal mineral exploration, and particularly relates to a method for evaluating the metallogenic potential of porphyry copper-(gold-molybdenum) deposits. Background Art

[0002] Porphyry copper deposits (especially those rich in Au and Mo) are important sources of metal minerals globally. Their metallogenic processes are usually related to the evolution of acidic intrusive rocks in arc environments and the exsolution of their hydrothermal fluids. Metals such as copper and its associated gold (Au) and molybdenum (Mo) migrate from magma into fluids and are concentrated into ores in the shallow crust through hydrothermal activities. However, not all arc magma systems have metallogenic potential, and the vast majority of arc magmas are poor ore magmas or only show weak mineralization. Therefore, in the actual mineral exploration process, rapid screening should be carried out according to certain conditions first to focus on exploration targets with metallogenic potential, so as to improve the efficiency of ore prospecting.

[0003] Porphyry copper metallogenic magmas usually have characteristics of high oxygen fugacity and water-rich. Under the conditions of high oxygen fugacity and water-rich, sulfides in magma are unstable and decompose, resulting in the enrichment of ore-forming elements in the exsolved fluids of magma. Therefore, magma systems with characteristics of high oxygen fugacity and water-rich are considered as prerequisites for having metallogenic potential and are objects that should be given priority attention in the process of porphyry copper mineral exploration.

[0004] Currently, traditional exploration and evaluation methods for porphyry copper deposits include regional geological surveys, rock geochemical analyses, geophysical explorations, and remote sensing ore prospecting, etc. These methods usually have problems such as long cycle, low efficiency, and high costs caused by them, and it is difficult to effectively and rapidly evaluate the metallogenic potential of magma systems. Therefore, developing a more efficient method for evaluating the metallogenic potential of porphyry copper deposits to narrow the actual exploration scope is of great significance for saving time, economic costs, and improving exploration efficiency. Summary of the Invention

[0005] Aiming at the defects of the prior art, the purpose of the present invention is to propose an evaluation method that can rapidly and accurately evaluate the metallogenic potential of porphyry copper-(gold-molybdenum) deposits, and this method can also accurately evaluate the enrichment degree and grade of Cu and its associated metals Au and Mo in porphyry copper-(gold-molybdenum) deposits with metallogenic potential.

[0006] The technical solution of the present invention is as follows:

[0007] A method for evaluating the metallogenic potential of porphyry copper-(gold-molybdenum) deposits, which includes:

[0008] (1) Sampling fresh and unaltered rock bodies in the area to be evaluated to obtain rock samples;

[0009] (2) Screen out magmatic zircons from the rock samples, and calculate the oxygen fugacity value of the magmatic zircons and the average oxygen fugacity value of the corresponding sampled rock mass. Based on the average oxygen fugacity value The sampled rock mass corresponding to the magmatic zircon with an oxygen fugacity offset ΔFMQ relative to the FMQ buffer pair higher than +1 is a candidate rock mass with high metallogenic potential;

[0010] (3) Screen out hornblende from the rock samples, and calculate the magmatic water content of the hornblende. The sampled rock mass corresponding to the hornblende with a magmatic water content of more than 5% is a candidate rock mass with high metallogenic potential;

[0011] (4) Take samples from the candidate rock masses. Select fresh and insignificantly altered rocks as samples to obtain sampled samples. Calculate the aluminum saturation index of the sampled samples, and determine the distribution coefficients of Cu, Au, and Mo between the fluid and the melt and / or the distribution coefficient ratios of Cu and Au, Cu and Mo, and Au and Mo in the candidate rock masses according to the aluminum saturation index;

[0012] (5) Conduct simulation calculations based on the obtained distribution coefficients and / or distribution coefficient ratios to obtain the content ratios of Au, Cu, and Mo, Cu in the candidate ore bodies, and evaluate the metallogenic potential of the candidate ore bodies according to the obtained content ratios; the simulation calculations use the Rayleigh fractionation model.

[0013] The above technical solutions of the present invention fully consider that the re-equilibration process of elements in zircons through chemical diffusion is extremely slow under magmatic temperature conditions, and its chemical composition is relatively sensitive to the redox state of the magmatic system. Therefore, magmatic zircons can be used as ideal tracer minerals to record magmatic evolution and changes in its physical and chemical properties; the crystallization of silicate minerals during the ascent of magma will cause the water in the magma to gradually become saturated, and this process is crucial for the extraction of ore-forming metals from the magma. Therefore, water-rich magma is also the key to mineralization; on this basis, calculating the total rock aluminum saturation index of the magma is an important step, which can fully evaluate the physical and chemical properties of the magma and its metallogenic potential. The inventor unexpectedly found that the aluminum saturation index has a significant impact on the Au / Cu and Mo / Cu content ratios in the magmatic exsolution fluid. Therefore, the Au / Cu and Mo / Cu content ratios of potential ore bodies in different ASI magmatic systems can be predicted based on the experimental and simulation calculation results.

[0014] In the above technical solution of the present invention, the relationship between the aluminum saturation index and the distribution coefficients of Cu, Au, and Mo between the fluid and the melt and / or the distribution coefficient ratios of Cu and Au, Cu and Mo, and Au and Mo can be obtained by conducting high-temperature and high-pressure experiments in the laboratory to simulate the distribution process of metal elements between magma and fluid, and systematically analyzing and detecting the products after the experiment to obtain the functional relationship between the magma aluminum saturation index and the distribution coefficients and / or distribution coefficient ratios.

[0015] According to some preferred embodiments of the present invention, the measurement of the average oxygen fugacity value of the sampled rock mass includes:

[0016] Collect multiple rock samples for each rock mass, respectively conduct screening of magmatic zircons, prepare samples of the screened magmatic zircons, use the clean area without cracks and inclusions as the analysis area, conduct trace element analysis of multiple analysis points by laser ablation inductively coupled plasma mass spectrometry at a beam spot size of 60 - 120 μm, and calculate the oxygen fugacity value of the magmatic zircon at the analysis point according to the trace element composition obtained at any analysis point. Take the average value of the oxygen fugacity values at all analysis points as the average oxygen fugacity value of the sampled rock mass.

[0017] According to some preferred embodiments of the present invention, the oxygen fugacity value of the magmatic zircon adopts the following calculation model:

[0018]

[0019] wherein, represents the oxygen fugacity value at the nth analysis point, Ce represents the cerium content in the magmatic zircon at this analysis point, U represents the uranium content in the magmatic zircon at this analysis point, and Ti represents the titanium content in the magmatic zircon at this analysis point.

[0020] According to some preferred embodiments of the present invention, the average oxygen fugacity value of the rock mass adopts the following calculation model:

[0021]

[0022] wherein, represents the oxygen fugacity value at the nth analysis point.

[0023] According to some preferred embodiments of the present invention, the measurement of the magma water content includes: analyzing the major element oxides and trace element contents of the amphibole by electron probe microanalysis, wherein the major element oxides include Na2O, K2O, CaO, MgO, FeO, Al2O3, SiO2, and the trace elements include Cl and F; according to the analysis results, the magma water content is calculated by the Amp-TB2 model.

[0024] According to some preferred embodiments of the present invention, in the analysis of the major element oxides and trace element contents, the analysis conditions for the major element oxides are an acceleration voltage of 15 kV, a beam current of 5 nA, and a beam spot diameter of 5 μm. Among them, the content measurements of Na2O and K2O use a peak counting time of 10 s and a background counting time of 5 s, and the content measurements of other major element oxides use a peak counting time of 20 s and a background counting time of 10 s; the analysis conditions for the trace elements are an acceleration voltage of 15 kV, a beam current of 20 nA, and a beam spot diameter of 15 μm, and the counting times are 120 s for the peak and 60 s for the background respectively.

[0025] Preferably, in the analysis of the trace element content, the glass standard sample as a known sample is measured regularly to control the long-term relative accuracy to 2%.

[0026] According to some preferred embodiments of the present invention, the measurement of the aluminum saturation index includes: analyzing the sampling sample by X-ray fluorescence spectrometry and / or inductively coupled plasma spectrometry to obtain its whole-rock chemical composition content and the contents of Al2O3, Na2O, K2O, and CaO therein; obtaining the aluminum saturation index ASI through the following calculation formula:

[0027] ASI = nAl2O3 / (nNa2O + nK2O + nCaO)

[0028] Wherein, nAl2O3, nNa2O, nK2O, and nCaO are the molar content percentages of Al2O3, Na2O, K2O, and CaO respectively.

[0029] According to some preferred embodiments of the present invention, the simulation calculation includes:

[0030] Setting the concentrations of Cu, Au, and Mo in the initial melt to be consistent with the average concentrations of these metals in typical arc magmas and magmas that form porphyry Cu-(Mo±Au) deposits;

[0031] Setting fluid exsolution to occur when the melt reaches water saturation, and setting the Cl content of the magma and the first batch of exsolved fluids to be consistent with the Cl element content range in typical arc magmas and the chlorinity range of fluid inclusions at the root of porphyry copper deposits;

[0032] It is set that Cl and water are completely incompatible with anhydrous crystalline minerals. According to experimental measurements, the magma-mineral distribution coefficients of Cu, Au, and Mo are set.

[0033] It is set that the melt reaches water saturation when the water content is 6 wt.%, and the corresponding confining pressure is 200 MPa.

[0034] The initial water content in the magma is set to the magma water content of hornblende measured in step (3).

[0035] According to the above settings, the differentiation process of fluids in an open magma chamber is simulated through the Rayleigh fractionation model. Among them, every 1 wt.% crystallization of the magma is set as one step, and the concentration of metal M in the magma fluid at different magma crystallinities is obtained, where M represents any one of Cu, Au, and Mo.

[0036] More preferably, the concentrations of Cu, Au, and Mo in the initial melt are set to 50 ppm, 2 ppb, and 2 ppm.

[0037] More preferably, when the melt starts to be water-saturated, that is, after 1 wt.% crystallization of the magma, the Cl element concentrations in the magma are set to 2000, 2300, and 2500 ppm, and the chlorinity of the first batch of exsolved fluids is set to 1, 2, and 4 mol / kg H2O.

[0038] More preferably, the magma-mineral distribution coefficients of Cu, Au, and Mo are set to 0.2, 0.1, and 0.2.

[0039] More preferably, the concentrations of metal M in the magma fluid at different magma crystallinities are obtained through the following calculation model:

[0040]

[0041] Where is the concentration of metal M in the fluid when the magma crystallinity is F, is the initial concentration of metal M in the magma, F is the crystallization degree of the magma, and D M is the distribution coefficient of metal M.

[0042] Furthermore, according to the above calculation results, the mass of metal M cumulatively extracted by the fluid when the magma crystallinity is F and the ratio of the masses of different metals M can be obtained through integration, that is, the potential grades and enrichment degrees of Cu, Au, and Mo in the ore body are obtained.

[0043] The present invention has the following beneficial effects:

[0044] The present invention can combine magma oxygen fugacity, magma water content, magma aluminum saturation index (ASI), metal distribution curves and numerical simulation calculations to construct a comprehensive metallogenic potential evaluation model; it can quickly identify the metallogenic potential in different magma systems, accurately judge the enrichment characteristics of copper, gold and molybdenum, and select appropriate exploration methods according to the characteristics of different deposit types;

[0045] The present invention can realize the evaluation of the metallogenic potential of porphyry copper deposit systems in a relatively short time, greatly improving the exploration efficiency;

[0046] The present invention is not only applicable to copper deposits, but also can be used for the evaluation of gold and molybdenum deposits, and can provide technical guidance for different types of porphyry copper ore districts, with strong adaptability and wide adaptability;

[0047] The present invention has significant cost advantages compared with traditional geological exploration methods, can greatly reduce the time and cost of on-site exploration, and improve the economic benefits of mineral resource exploration. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a relationship diagram between Cu-Au-Mo distribution coefficients and magma ASI in Example 3.

[0049] Figure 2 It is a relationship diagram between the ratio of Cu-Au-Mo distribution coefficients and magma ASI in Example 3.

[0050] Figure 3 It is a range diagram of Au / Cu and Mo / Cu ratios in porphyry copper deposits formed by magmas with different ASIs in Example 3, and the initial H2O content (starting H2O) of the magma is set to 2 and 6 wt% respectively. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0051] The technical solutions in the present invention will be further described below in conjunction with the embodiments of the present invention. The embodiments described below are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0052] Example 1

[0053] The evaluation of the metallogenic potential of porphyry copper deposits based on oxygen fugacity values is carried out through the following steps:

[0054] (1) Representative, fresh, and unaltered intrusive rocks are selected in the exploration area through field observation for sample collection. 5 - 10 samples are collected from each rock mass. The collected samples are crushed and magmatic zircons are screened out. Approximately 10 magmatic zircons are selected from each rock mass. During the screening process, existing inclusions or weathered magmatic zircons are avoided to ensure the accuracy of the analysis results;

[0055] (2) The screened magmatic zircons are fixed on an epoxy resin target and polished. Observed under a microscope and cathodoluminescence (CL), areas that are clean, free of cracks and inclusions are selected as analysis areas. Trace element analysis is carried out by laser ablation inductively coupled plasma mass spectrometry (LA - ICP - MS) with a beam spot size of 60 - 120 μm. The oxygen fugacity value of the magmatic zircons in the rock mass and the average oxygen fugacity value of the magma are calculated based on the obtained trace element composition.

[0056] (3) Rock masses with an offset ΔFMQ of the average oxygen fugacity value relative to the oxygen fugacity of the FMQ buffer pair (hereinafter directly represented by FMQ) higher than +1 are selected as candidate rock masses with high metallogenic potential.

[0057] Among them, the oxygen fugacity value of zircons at any analysis point n is calculated as follows:

[0058]

[0059] Among them, Ce represents the cerium content in magmatic zircons, U represents the uranium content in magmatic zircons, and Ti represents the titanium content in magmatic zircons.

[0060] The average magma oxygen fugacity value adopts the following calculation model:

[0061]

[0062] In this embodiment, according to the above steps, the average oxygen fugacity values of andesite in the Pliocene - Pleistocene arc magmas in the western Pacific and the ore - forming magmas of Cu - (Au ± Mo) deposits in the east - west Pacific arc segments, including the Grasberg deposit, Ok Tedi deposit, and El Teniente deposit, are statistically analyzed. Values, the former is FMQ - 0.8 to FMQ + 0.4 (i.e., ΔFMQ = -0.8 to +0.4), and the latter are FMQ + 0.9 to FMQ + 1.7 (i.e., ΔFMQ = +0.9 to +1.7), FMQ + 0.4 to FMQ + 1.7 ((i.e., ΔFMQ = +0.4 to +1.7)), FMQ + 1.4 to FMQ + 2.2 (i.e., ΔFMQ = +1.4 to +2.2) in turn. The calculation results are consistent with the actual geological conditions, that is, the andesite at this place does not contain porphyry copper deposits, while the magmatic rocks in the Grasberg area, Ok Tedi area, and El Teniente area all contain large porphyry copper deposits.

[0063] Example 2

[0064] The evaluation of the metallogenic potential of porphyry copper deposits based on the content of magmatic water is carried out through the following steps:

[0065] (1) Select fresh, unaltered, and hornblende samples without obvious signs of metamorphism from the collected samples obtained in Example 1;

[0066] (2) Analyze the major element oxides and trace element contents of the hornblende samples by electron probe microanalysis. Among them, the major element oxides include Na2O, K2O, CaO, MgO, FeO, Al2O3, SiO2, and the trace elements include Cl and F; among them, the analysis conditions for the major element oxides are an acceleration voltage of 15 kV, a beam current of 5 nA, and a beam spot diameter of 5 μm. And for the measurement of the contents of Na2O and K2O, a peak counting time of 10 s and a background counting time of 5 s are used to minimize the loss of these elements during the analysis process, and the other major element oxides are analyzed using a peak counting time of 20 s and a background counting time of 10 s; the detection conditions for the trace elements Cl and F are an acceleration voltage of 15 kV, a beam current of 20 nA, and a beam spot diameter of 15 μm, and the counting times are 120 s for the peak and 60 s for the background respectively. When detecting the contents of Cl and F elements, the glass standard sample as a known sample is measured regularly to control the long-term relative accuracy to 2%;

[0067] (3) According to the analysis results, calculate the magmatic water content through the Amp - TB2 model. If the water content exceeds 5%, it is considered that the magma has metallogenic potential, and the corresponding rock mass is a candidate rock mass with high metallogenic potential.

[0068] Example 3

[0069] The evaluation of the metallogenic potential of porphyry copper deposits is carried out through the following steps, and the grades of Cu and associated metals Mo and Cu are evaluated:

[0070] (1) Samples were taken from the candidate rock masses screened in Examples 1 and 2. The samples were fresh rocks without significant alteration.

[0071] (2) Approximately 20 g of the rock samples were crushed into small particles and ground into fine powder using a ball mill or vibration mill. The particle size was controlled below 200 mesh and dried in an oven at 110 °C to remove moisture, obtaining dry sample powder.

[0072] (3) The dry sample powder was added to a covered Teflon beaker, and hydrofluoric acid and nitric acid were added in sequence. It was heated until the sample was completely dissolved to obtain a sample solution.

[0073] (4) The sample solution was purified by ion exchange method to obtain a purified sample solution.

[0074] (5) Elemental analysis of the purified sample solution was carried out by ICP - OES (Inductively Coupled Plasma Optical Emission Spectrometry) to determine the contents of Al2O3, Na2O, K2O and CaO in it.

[0075] (6) Based on the measurement results, the whole - rock aluminum saturation index (ASI) of the sample was calculated as follows:

[0076] ASI = nAl2O3 / (nNa2O + nK2O + nCaO)

[0077] where nAl2O3, nNa2O, nK2O and nCaO are the molar content percentages of the corresponding oxides respectively.

[0078] (7) According to the calculated ASI value, through the relationship diagram of Cu - Au - Mo distribution coefficient and magma ASI as shown in the appendix Figure 1 , the distribution coefficients of Cu, Au, and Mo of the ore bodies in the candidate rock masses corresponding to the samples between fluid - melt were determined. Through the relationship diagram of the ratio of Cu - Au - Mo distribution coefficients and magma ASI as shown in the appendix Figure 2 , the distribution coefficient ratios D Cu / D Au of Cu and Au, the distribution coefficient ratios D Cu / D Mo of Cu and Mo, and the distribution coefficient ratios D Au / D Mo of Au and Mo of the ore bodies in the candidate rock masses corresponding to the samples were determined;

[0079] (8) Simulation calculations were carried out based on the obtained distribution coefficient ratios to obtain the Au / Cu and Mo / Cu content ratios of the candidate ore bodies. The metallogenic potential of the candidate ore bodies was evaluated based on the obtained content ratios. Among them, the Rayleigh fractionation model was used for the simulation calculations. The simulation calculation process includes:

[0080] The concentrations of Cu, Au, and Mo in the initial melt were set to 50 ppm, 2 ppb, and 2 ppm, respectively, which are similar to the average contents of these metals in typical arc magmas and magmas that form porphyry Cu-(Mo±Au) deposits;

[0081] The Cl element concentrations in the melt at the start of H2O saturation, i.e., after 1 wt.% of magma crystallization, were set to 2000, 2300, and 2500 ppm, respectively, and the chlorinities of the first partitioning fractions of the fractionated fluid were set to 1, 2, and 4 mol / kg H2O, covering the range of Cl element concentrations in typical arc magmas and the chlorinity range of the fractionated fluid at the root of the porphyry copper deposit system;

[0082] It was assumed that Cl and H2O are completely incompatible with anhydrous crystalline minerals to simplify the model;

[0083] Based on the fact that Cu, Au, and Mo are mostly incompatible relative to the major silicate minerals including plagioclase, pyroxene, and amphibole, and a small amount of magnetite during magma crystallization, the magma / mineral distribution coefficients of Cu, Au, and Mo were set to 0.2, 0.1, and 0.2, respectively, according to experimental determinations;

[0084] It was assumed that the melt reaches H2O saturation when the H2O content is 6 wt.%, corresponding to a confining pressure of 200 MPa, and the initial H2O content in the magma was set according to the calculation results of Example 2;

[0085] Based on the above settings, the differentiation process of the fluid in an open magma chamber was simulated using the Rayleigh fractionation model, step by step for every 1 wt.% of crystallization, and the calculation model was specifically used to obtain the metal concentrations in the magmatic fluid at different degrees of crystallization, and the relationship diagram between the metal content ratio of the potential ore bodies formed by magmas with different ASI values and ASI as shown in the appendix Figure 3 could be obtained, so as to determine the metal content ratio according to the ASI of the candidate rock mass and determine its ore-forming potential.

[0086] Example 4

[0087] The ore-forming potential of the Grasberg Cu-Au deposit and the El Teniente Cu-Mo deposit was evaluated according to the process of Example 3. After detection, the whole-rock aluminum saturation indices of the two were 1.1 and 1.3, respectively. The simulation calculation results showed that the average Au / Cu and Mo / Cu ratios of their ore bodies were ~0.8 - 0.9×10-4 and ~0.015, respectively, which were very close to the measured Au / Cu and Mo / Cu ratios of the Grasberg Cu-Au deposit and the El Teniente Cu-Mo deposit (respectively ~0.9 - 1.2×10-4 and ~0.026), indicating that the evaluation method of the present invention is accurate and effective.

[0088] It should be noted that the above are only the preferred embodiments of the present invention, and should not limit the protection scope of the technical solution of the present invention. Any modification of the technical solutions described in the foregoing embodiments by those of ordinary skill in the art within the spirit and principle of the present invention, and any equivalent replacement of technical features, etc., shall be included within the protection scope of the present invention.

Claims

1. A method for evaluating the metallogenic potential of porphyry copper-(gold-molybdenum) deposits, characterized in that It includes: (1) Sampling fresh and unaltered rock masses in the area to be evaluated to obtain rock samples; (2) Screen out magmatic zircons from the rock samples, and calculate the oxygen fugacity value of the magmatic zircons and the average oxygen fugacity value of the corresponding sampled rock mass. Based on the average oxygen fugacity value The sampled rock mass corresponding to magmatic zircons with an oxygen fugacity offset ΔFMQ relative to the FMQ buffer pair higher than +1 is a candidate rock mass with high metallogenic potential. (3) Screening amphibole from the rock samples, calculating the magmatic water content of the amphibole, and taking the sampling rock mass corresponding to the amphibole with a magmatic water content of more than 5% as a candidate rock mass with high mineralization potential; (4) Sampling the candidate rock mass, selecting fresh and insignificantly altered rocks as samples to obtain sampling samples, calculating the aluminum saturation index of the sampling samples, and determining the distribution coefficients of Cu, Au, and Mo between fluid and melt and / or the distribution coefficient ratios of Cu and Au, Cu and Mo, and Au and Mo in the candidate rock mass according to the aluminum saturation index; (5) Conducting simulation calculations based on the obtained distribution coefficients and / or distribution coefficient ratios to obtain the content ratios of Au, Cu, and Mo, Cu in the candidate ore body, and evaluating the mineralization potential of the candidate ore body according to the obtained content ratios; the simulation calculation uses the Rayleigh fractionation model.

2. The evaluation method according to claim 1, wherein The measurement of the average oxygen fugacity value of the sampled rock mass includes: Collect multiple rock samples for each rock mass, separately conduct screening of magmatic zircons, prepare samples of the screened magmatic zircons, use the clean area without cracks and inclusions as the analysis area, conduct trace element analysis of multiple analysis points by laser ablation inductively coupled plasma mass spectrometry at a spot size of 60 - 120 μm, and calculate the oxygen fugacity value of the magmatic zircons at any analysis point according to the trace element composition obtained at that analysis point Use the average value of the oxygen fugacity values at all analysis points as the average oxygen fugacity value of the sampled rock mass 3. The evaluation method according to claim 2, characterized in that Among them, The oxygen fugacity value of the magmatic zircon Adopts the following calculation model: Among them, represents the oxygen fugacity value at the nth analysis point, Ce represents the cerium content in magmatic zircon at this analysis point, U represents the uranium content in magmatic zircon at this analysis point, and Ti represents the titanium content in magmatic zircon at this analysis point; and / or, the average oxygen fugacity value adopts the following calculation model:

4. The evaluation method according to claim 1, wherein The calculation of the magmatic water content includes: analyzing the major element oxides and trace element contents of the amphibole by electron probe microanalysis. Among them, the major element oxides include Na2O, K2O, CaO, MgO, FeO, Al2O3, and SiO2, and the trace elements include Cl and F; according to the analysis results, the magmatic water content is calculated by the Amp-TB2 model.

5. The evaluation method according to claim 4, wherein In the analysis of the major element oxides and trace element contents, the analysis conditions for the major element oxides are an acceleration voltage of 15 kV, a beam current of 5 nA, and a beam spot diameter of 5 μm. Among them, the content measurements of Na2O and K2O use a peak counting time of 10 s and a background counting time of 5 s, and the content measurements of other major element oxides use a peak counting time of 20 s and a background counting time of 10 s; the analysis conditions for the trace elements are an acceleration voltage of 15 kV, a beam current of 20 nA, and a beam spot diameter of 15 μm, and the counting times are 120 s for the peak and 60 s for the background respectively.

6. The evaluation method according to claim 1, wherein The calculation of the aluminum saturation index includes: analyzing the sampling samples by X-ray fluorescence spectrometry and / or inductively coupled plasma spectrometry to obtain their whole-rock chemical composition contents and the contents of Al2O3, Na2O, K2O, and CaO therein; obtaining the aluminum saturation index ASI through the following calculation formula: ASI = nAl2O3 / (nNa2O + nK2O + nCaO) Among them, nAl2O3, nNa2O, nK2O, and nCaO are the molar content percentages of Al2O3, Na2O, K2O, and CaO respectively.

7. The evaluation method according to claim 1, characterized in that The simulation calculation includes: Setting the concentrations of Cu, Au, and Mo in the initial melt to be consistent with the average concentrations of these metals in typical arc magmas and magmas that form porphyry Cu-(Mo±Au) deposits; Setting fluid exsolution to occur when the melt becomes water-saturated, and setting the Cl content of the magma and the first batch of exsolved fluids to be consistent with the Cl element content range in typical arc magmas and the chlorinity range of fluid inclusions at the root of porphyry copper deposits; Set Cl and water to be completely incompatible with anhydrous crystalline minerals. According to experimental measurements, set the magma-mineral distribution coefficients of Cu, Au, and Mo. Set the melt to reach water saturation when the water content is 6 wt.%, and the corresponding confining pressure is 200 MPa. Set the initial water content in the magma to be the magma water content of hornblende measured in step (3). Based on the above settings, simulate the differentiation process of fluids in an open magma chamber through the Rayleigh fractionation model. Among them, every 1 wt.% of magma crystallization is set as one step, and the concentrations of metal M in the magma fluid at different magma crystallinities are obtained, where M represents any one of Cu, Au, and Mo.

8. The evaluation method according to claim 7, wherein Among them, The concentrations of Cu, Au, and Mo in the initial melt are set to 50 ppm, 2 ppb, and 2 ppm; and / or, the Cl element concentration in the magma when the melt starts to be water-saturated, that is, after 1 wt.% of magma crystallization, is set to 2000, 2300, and 2500 ppm, and the chlorinity of the first exsolved fluid is set to 1, 2, and 4 mol / kg H2O.

9. The evaluation method according to claim 7, wherein The magma-mineral distribution coefficients of Cu, Au, and Mo are set to 0.2, 0.1, and 0.

2.

10. The evaluation method according to claim 7, characterized in that The concentrations of metal M in the magma fluid at different magma crystallinities are obtained through the following calculation model: wherein is the concentration of metal M in the fluid when the magma crystallinity is F, is the initial concentration of metal M in the magma, F is the crystallization degree of the magma, and D M is the distribution coefficient of metal M.

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