Rock geochemical identification method of endogenous gold and polymetallic mine concealed metallogenic system

Abstract

The invention relates to the technical field of exploration, prediction and evaluation of solid mineral resources, and particularly discloses a rock geochemical identification method of an endogenous gold and polymetallic mine concealed metallogenic system, which is applicable to conditions and data bases: construction environmental condition elements, construction, magma and metallogenic unit elements, magma rock magma period division elements, and rock magma period division elements. Rock geochemical data elements; sample collection and data analysis requirements are as follows: samples are unweathered magmatic rocks obtained in a target area, magmatic activity time sequence division, attribute distinguishing and evolution mode discrimination are carried out for the target area, and magmatic rock combination feature elements and evolution trends with metallogenic attributes in the magmatic evolution process are identified; the mineralization system identification method comprises the steps of magma system division, magma origin, evolution mode and attribute judgment, and identification of a mineralization potential area. According to the method, the gold and polymetallic ore mineralization system prediction is carried out according to the magmatic rock combination attribute characteristics and the magmatic evolution process, and the prediction risk of the endogenous gold and polymetallic ore mineralization system is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of solid mineral resource exploration, prediction and evaluation, and in particular to a rock geochemical identification method for endogenous gold and polymetallic ore concealed mineralization systems. Background Art

[0002] The existence of a mineralization system is an important reference indicator in mineralization prediction, and the evolution of magma is closely related to the formation of a mineralization system.

[0003] The "Trinity" prospecting and prediction method uses metallogenic geological bodies, metallogenic structural surfaces, and metallogenic characteristic markers as the three key elements of mineralization prediction. In the formation of endogenous metal deposits related to magmatism, magmatic activity is the core element in the composition of the mineralized geological body. Previous studies have suggested that numerous magmatic evolutionary processes, including magma formation, assimilation and contamination during magma ascent, magma mixing, and crystallization differentiation, can all lead to element differentiation, enrichment, migration, and precipitation. The mineralization system of an endogenous deposit is the product of physical and chemical reactions at specific stages of these magmatic evolutionary processes. Its components include ore-forming material composition, ore-forming fluids, energy sources, ore-controlling factors, ore-forming processes, and time and space. Among these, magmatic activity, which is closely related to these elements, is the key to the formation of the mineralization system.

[0004] A metallogenic system is a natural system with metallogenic properties, encompassing all geological elements and processes that control the formation, evolution, and preservation of ore deposits within a specific geological time and space domain, as well as the resulting series of ore deposits and mineralized anomalies. A magmatic-hydrothermal ore-forming system is an endogenous ore-forming system that develops within a specific geological period and is genetically linked to the tectonic and magmatic activity of that period. Formed under specific tectonic settings, a magmatic-hydrothermal ore-forming system can form a series of intrinsically linked ore deposit types, such as gold, silver, lead, zinc, copper, molybdenum, and iron, constituting a magmatic-hydrothermal ore-forming series. During the metallogenic process, the associated mineralization (i.e., the geological process that forms the ore deposit) is often the product of a specific stage of evolution of the magmatic system. The formation of a specific type of igneous rock assemblage indicates that the magmatic activity at that stage possessed metallogenic properties, i.e., the metallogenic specificity of the igneous rocks.

[0005] Throughout geological history, the evolution of magma often forms igneous rocks with distinct temporal and spatial distribution characteristics and properties. Therefore, using time and space as axes and the assemblage of igneous rocks with different properties as research targets, we can trace the evolution of magma and reconstruct the magma system. Furthermore, we can identify whether the magma process at a particular stage has mineralization-specific characteristics, predict the existence of a mineralization system, and thus select mineral resource exploration targets.

[0006] By identifying the properties of different stages in the magma evolution process, it is possible to predict whether there is a hidden mineralization system, providing a basis for the exploration of hidden mineral deposits.

[0007] The formation of endogenous metal deposits in eastern China is closely related to Mesozoic magmatic activity, resulting in magmatic and hydrothermal deposits of gold, silver, copper, lead, zinc, iron, and molybdenum. Currently, with the advancement of resource exploration, the focus is shifting towards deep exploration, primarily targeting concealed deposits. This increased depth has led to a decrease in the effectiveness of exploration methods and a sharp increase in exploration costs. Evaluating and optimizing mineralization zones based on known information, selecting prospective mineralization areas, and identifying concealed underground exploration targets are prerequisites and essential steps for conducting specific exploration work. They are also the main focus of current scientific research and a key technical bottleneck. Recent research advances have shown that identifying concealed mineralization systems deep underground through surface-visible structural, magmatic, and mineralization indicators is an effective means of predicting exploration directions, optimizing exploration areas, and narrowing down exploration targets.

[0008] Existing research indicates that the formation of gold and polymetallic deposits, exemplified by the Jiaodong gold deposit, is closely related to the interaction between crust-derived and mantle-derived magmas during the convergent plate environment of that period. Magmatic activity, represented by igneous rock assemblages characterized by crust-mantle interaction, is genetically linked to the formation of endogenous magmatic hydrothermal deposits of gold and polymetallic minerals (such as silver, lead, zinc, copper, and molybdenum). Previous studies have revealed the genetic connection between mineralization outbreaks and magmatic activity, namely, that crust-mantle magma interaction led to large-scale mineralization outbreaks; recent research has further revealed the mechanisms and processes of crust-mantle interaction. Based on recent theoretical advances and relevant data, this paper proposes a petrologic geochemical identification method for concealed endogenous gold and polymetallic mineralization systems, addressing the gap in the prediction of endogenous gold and polymetallic mineralization systems using the properties of igneous rock assemblages. Summary of the Invention

[0009] To address the existing challenges in the existing technology, the present invention aims to provide a litho-geochemical identification method for concealed mineralization systems of endogenous gold and polymetallic minerals, addressing the current technical difficulties in deep resource exploration, such as uncertain exploration directions and difficulty identifying exploration targets. This method, based on surface petrological and litho-geochemical data, characterizes magma evolution processes and patterns, identifies mineralization-specific crust-mantle interactions modeled after magma mixing, and predicts hidden mineralization systems associated with the formation of endogenous gold and polymetallic (silver, lead, zinc, copper, molybdenum, and other minerals) deposits. This method provides a basis for optimizing gold and polymetallic mineralization prediction areas and identifying exploration targets. Specifically, this method establishes a set of graphical models for analyzing magma evolution processes based on the properties of igneous rock assemblages, encompassing specialized fields such as petrology, ore deposits, and mineral resource exploration.

[0010] The technical solution adopted by the present invention to solve the technical problem is: a rock geochemical identification method for endogenous gold and polymetallic ore concealed mineralization systems, comprising the following steps: S1. Applicable conditions and data basis: Applicable conditions include four aspects: tectonic environment conditions, tectonic, magmatic and metallogenic units, magmatic stage division of igneous rocks, and rock geochemical data. The data basis includes zircon U-Pb age data, whole-rock rock geochemical analysis data, and trace and rare earth element analysis data. S2. Sample collection and data analysis requirements: Rock samples shall be collected from the target area. The samples shall be non-weathered igneous rocks obtained in the target area. The magmatic activity time sequence, attribute differentiation, and evolution pattern discrimination shall be carried out in the target area. The characteristic elements and evolution trends of the magmatic rock assemblages with metallogenic properties during the magmatic evolution process shall be identified. S3. Method for identifying mineralization system: S31. Magmatic System Stage Division: Determine the intrusion time of magmatic rocks based on zircon U-Pb age data, divide the magmatic activity stages, establish a silica-alkali map, and plot the components of magmatic rock samples according to the magmatic activity time sequence in the silica-alkali map. Establish a distribution pattern map of magmatic rocks of different stages, and divide the component end members of magmatic rocks of different time sequences. Determine the existence of two or more component end members in the same stage of magmatic evolution based on the basicity and total alkali content of the magmatic rocks. Component end members include basic end members, acidic end members, and alkaline end members. Determine that within the rock assemblage of magmatic rocks of the same time sequence, there is a magma evolution basis with basic end members and acidic end members as the two poles, and a magma mixing model, where the alkaline end member is not required. S32. Magma Origin, Evolution Pattern, and Attribute Determination: Establish W(Sr / Y)-W(Y) diagrams and Si-K discriminant diagrams, and use these diagrams to identify magmatic systems with metallogenic properties. Magmatic rock assemblages with metallogenic potential are judged to exhibit mixed characteristics of crust and mantle components, as measured by different indicators. Projecting the rock components of magmatic rocks from the same period on the W(Sr / Y)-W(Y) diagram reveals that magmatic rock assemblages with metallogenic potential exhibit a continuous distribution from the adakite magmatic rock area to the volcanic arc magmatic rock area, demonstrating a mixture of different types of magma formed by inconsistent melting driven by tectonic movement. Projecting magmatic rock assemblages from the same period on the Si-K discriminant diagram reveals that magmatic rock assemblages with metallogenic properties exhibit evolution from the basanite series to the high-potassium calc-alkaline series and the calc-alkaline series. The presence of these characteristics in magmatic rock assemblages from the same period suggests that the magmatic system formed by magmatic activity in this region has the potential to form gold and polymetallic mineralization. S33. Identification of mineralization potential areas: Based on the above judgment results, combined with the abnormal characteristics of single or multiple element combinations of gold, silver, lead, zinc, copper, molybdenum and iron obtained from regional rock geochemical measurements in geochemical exploration, it is predicted that there is a hidden mineralization system related to magmatic activity in the target area, which has the conditions for the formation of endogenous deposits of the above mineral species, and relevant resource exploration is carried out.

[0011] Specifically, the tectonic environmental condition elements in step S1 are specifically applicable to the tectonic environment of ocean-continent subduction and continent-continent collision formed by plate convergence. In the above environment, there is a strong crust-mantle interaction formed by the subduction of the crust and the upwelling of mantle-derived magma.

[0012] Specifically, the structural, magmatic and metallogenic unit elements in step S1 are that the target area should be located in a metallogenic sub-region or ore field in the five-level metallogenic unit classification system, and should be a potential structural, magmatic and metallogenic distribution zone. The specific characteristic elements include the following three items: (1) There are fault structures that cut through the lithosphere in the target area, which are characterized by the presence of strike-slip faults or strike-slip fault bundles, dike groups, and rock stock-like rock bodies, that is, the existence of a tectonic-magmatic activity zone; (2) Rock stocks or dike groups with crust-mantle mixing characteristics are distributed along the tectonic-magmatic activity belt; (3) The presence of primary mineralization of gold, polymetallic materials, etc. or corresponding 1:200,000 or 1:50,000 rock geochemical anomalies on the surface.

[0013] Specifically, the elements for dividing the magmatic stages of igneous rocks in step S1 are to systematically collect magmatic rock samples in the target area, including various magmatic rocks produced in the form of vein rocks, carry out diagenetic chronology tests, use isotope chronology to determine the time of magmatic activity, such as the zircon U-Pb dating method, divide the magmatic activity time sequence, and establish a magmatic activity stage model.

[0014] Specifically, the rock geochemical data elements in step S1 are based on the whole rock geochemical analysis and trace element and rare earth element analysis data. Therefore, on the basis of systematic sampling, the rock geochemical whole rock analysis should be carried out in accordance with the corresponding specifications, including the whole rock analysis of silicate major elements, including: SiO2, Al2O3, TFe2O3, CaO, MgO, K2O, Na2O, P2O5, TiO2, MnO and H2O - 、H2O + The analysis of major elements SiO2 and LOI was conducted by gravimetric method, TFe2O3, CaO, MgO, K2O, Na2O, P2O5, TiO2 and MnO were conducted by inductively coupled plasma atomic emission spectrometry, and trace elements and rare earth elements, including Nb, Ta, Sr and Y, were analyzed.

[0015] Specifically, the sample collection in step S2 includes: collecting rock samples from the target area; the samples are igneous rocks available in the target area, including various types of vein rocks; the samples are outcrop blocks and drill cores; the samples should be fresh rocks without alteration and weathering characteristics; the sampling mass of geochemical samples should be greater than 500g; the sampling mass of zircon U-Pb dating test samples should be 2-5kg, and the sampling mass should be determined based on the acidity or basicity of the rock. Zircon U-Pb dating sample processing involves the following steps: Single zircon crystals are selected through sample crushing and separation according to artificial heavy sand treatment requirements; these selected zircon crystals are embedded in epoxy resin and polished for target preparation; cathodoluminescence (CL) imaging is used to examine the zircon's internal structure and determine the appropriate location for in situ zircon U-Pb dating, with the goal of determining the last date of magmatic activity. The number of single zircon crystals required to generate at least 15 valid data points is sufficient for statistical analysis. Processing of rock geochemical test samples: Use a pollution-free sample crusher to prepare whole rock powder samples, and process the samples through coarse crushing, medium crushing and fine crushing. The sample particle size should reach 200 mesh, and the mass of the sample after reduction should be >150g.

[0016] Specifically, the alkaline end member in step S31 is not required to be a magma with mineralization properties. The magma evolution process is manifested as a mixture of basic magma and acidic magma, and alkaline acidic magma is derived to form alkaline end members; it shows the existence of basic characteristics of magma mixing, magma end member characteristics, and magma evolution patterns of magma mixing end member composition, path and products.

[0017] Specifically, in step S32, the rock components of the same period of igneous rocks are projected to carry out the identification of the properties and evolution trends of the mixed igneous rocks. In the silicon-potassium discrimination diagram, the igneous rock combination with mineralization properties has the characteristics of evolving from the basanite series to the high-potassium calc-alkaline series and the calc-alkaline series. The essence of this is that the mineralization properties of the magma are derived from the extraction and enrichment of mineralization elements by magmatic hydrothermal fluids caused by the mixing of mantle-derived high-potassium and low-calcium alkaline magma and crust-derived calc-alkaline magma.

[0018] Specifically, the different indicators in step S32 include but are not limited to the mixing characteristics of the shell and mantle components with Nb / Ta as the indicator. The W(Nb / Ta)-W(SiO2) diagram is also established to judge the origin, evolution mode and properties of the magma. The rock components of the magma of the same period are projected and the combination distribution pattern is judged in the W(Nb / Ta)-W(SiO2) diagram. The magma combination with mineralization potential presents the mixing characteristics of the shell and mantle components with Nb / Ta as the indicator. The essence of this is to judge the origin, evolution mode and property of the magma. Originated from the mantle and crust; the rock components of igneous rocks of the same period are projected, and the origin and magma mixing pattern of the igneous rock combination of the same period are judged. The igneous rock combination with mineralization potential presents the following characteristics: the igneous rocks with component end-member characteristics indicated by Nb / Ta are originated from the crust or mantle; other rock combinations of the same period are distributed between the crust-derived and mantle-derived magma end-members, forming a component transition zone with the end-member components as the starting and ending points; the essence is to judge whether the mixed magma originated from the lithospheric crust and lithospheric mantle respectively.

[0019] Specifically, in step S32, the rock components of the igneous rocks of the same period are projected to identify the genetic environment and evolutionary trend of the igneous rocks. The existence of adakite indicates that the origin of the magma is inconsistent melting driven by tectonic movements such as plate subduction or thickening of the lithosphere; at the same time, projection comparisons of different periods are performed. The igneous rock assemblages with mineralization potential are continuously distributed from the adakite igneous rock area to the volcanic arc igneous rock area, and are mainly concentrated in the intersection area between the adakite igneous rock area and the volcanic arc igneous rock area, showing a mixture of different types of magma formed by inconsistent melting driven by tectonic movements.

[0020] The present invention has the following beneficial effects: The rock geochemical identification method of endogenous gold and polymetallic mineral concealed mineralization system designed in the present invention is based on the latest theoretical understanding of the relevant mineralization mechanism research. The latest research system portrays the magmatic process related to gold mineralization and conducts regional comparison with the western Shandong region. The research results show that mineralization occurs in the mixing process of mantle-derived magma and crust-derived magma. In this process, magmas with different genetic characteristics and properties mix with each other to form new magmas with mineralization properties, leading to the occurrence of mineralization. This process is recorded by the igneous rock combination of the same magmatic period, forming a recognizable magma evolution pattern with significant characteristics, which establishes a theoretical basis for this technical invention.

[0021] The rock geochemical identification method for concealed mineralization systems of endogenous gold and polymetallic ores designed in the present invention determines various indicators to identify the combination characteristics of igneous rocks and the temporal and spatial evolution trends, and predicts whether there is a potential mineralization system closely related to magma activity. It provides a basis for evaluating the mineralization potential of mineralization zones and searching for concealed deposits, reduces the risk of deep prospecting for endogenous gold and polymetallic ores, and for the first time forms a technical method for predicting gold and polymetallic mineralization systems based on the rock combination attribute characteristics of igneous rocks and the magma evolution process. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a silica-alkali diagram of the mineralizing magmatic rock assemblage W(SiO2)-W(K2O+Na2O) magma evolution trend discrimination diagram.

[0023] Figure 2 It is the W(Nb / Ta)-W(SiO2) discrimination diagram of the origin of mineralized igneous rock materials and magma mixing.

[0024] Figure 3 It is the W(Sr / Y)-W(Y) discrimination diagram of the genesis and evolution trend of mineralized igneous rock assemblages.

[0025] Figure 4 It is a discriminant diagram of the W(SiO2)-W(K2O) magma evolution trend of the mineralizing magmatic rock combination.

[0026] In the figure: 1-olivine gabbro (picrite basalt); 2a-alkaline gabbro (basalt); 2b-subalkaline gabbro (basalt); 3-gabbro diorite (basaltic andesite); 4-diorite (andesite); 5-granodiorite (dacite); 6-granite (rhyolite); 7-siliceous quartz (rhyolite); 8-monzogabbro (trachyte basalt); 9-monzogabbro (basaltic diorite) Trachy andesite); 10-monzonite (trachy andesite); 11-quartz monzonite (trachy dacite); 12-syenite (trachyte); 13-parabasinite gabbro (basanite, basanite); 14-parabasinite monzonite diorite (phononite); 15-parabasinite monzonite syenite (phononite); 16-parabasinite syenite (phononite); 17-parabasinite plutonic rock (parabasinite volcanic rock). DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0028] This invention, based on previous fundamental research findings and relevant exploration cases, has developed a practical technical approach. Research on the mineralization mechanism in the Jiaodong region, a major gold mineralization concentration in eastern China, has shown that the region's mineralization is genetically linked to the mixing of crust- and mantle-derived magmas during the Mesozoic. This understanding breaks with existing theoretical understanding that gold mineralization is related to crust-mantle interactions and lays the foundation for the translation of this theoretical breakthrough into innovative technical approaches.

[0029] The study shows that the magmatic rock combination with mineralization exclusivity is the product of the mixture of high-potassium, low-calcium alkaline basic magma of mantle origin and calc-alkaline acidic magma of crustal origin. This type of rock combination shows the characteristics of evolution from high-potassium, low-calcium alkaline series to high-potassium calc-alkaline series. It is the product of the evolution of the magma system formed under a certain tectonic environment to a certain stage. The present study compared the characteristics of magma evolution in the Jiaodong area and the western Shandong area during the same mineralization period, and the two have the same characteristic properties. From the perspective of the dynamics of tectonic movement-induced magmatic activity, the formation mechanism of this type of magmatic activity and mineralization exists in tectonic environments such as ocean-continent subduction and continent-continent collision formed by plate convergence, indicating that this method is also applicable in the above environments.

[0030] Based on the latest understanding of the tectonic environment and known metallogenic systems in the Jiaodong and western Shandong regions of Shandong Province, as well as research findings on mineralization factors such as the characteristics of associated igneous rock assemblages and the evolutionary trends of magmatic activity, this paper provides a technical method and approach for identifying metallogenic systems formed by endogenous mineralization associated with magmatic activity, which form metallogenic series of gold and polymetallic (silver, lead, zinc, copper, molybdenum, and iron) mineralization. This method provides a basis for finding concealed mineral deposits and optimizing exploration targets. This metallogenic system can form different types of deposits, including epithermal, skarn, and porphyry deposits.

[0031] A rock geochemical identification method for endogenous gold and polymetallic ore concealed mineralization systems comprises the following steps: 1. Applicable conditions and data basis: Applicable conditions include the following four aspects.

[0032] 1) Tectonic, magmatic, and metallogenic unit elements: The target area should be located within a metallogenic sub-region or ore field within the five-level metallogenic unit classification system and be a potential distribution zone of tectonic, magmatic, and metallogenic activities. Specific characteristic elements include the following three items: (1) There are fault structures that cut through the lithosphere in the target area, which are characterized by the presence of strike-slip faults or strike-slip fault bundles, dike groups, and rock stock-like rock bodies, that is, the existence of a tectonic-magmatic activity zone.

[0033] (2) Along the tectonic-magmatic activity belt, there are rock stocks or vein groups with crust-mantle mixing characteristics.

[0034] (3) The presence of primary mineralization of gold, polymetallic materials, etc. or corresponding 1:200,000 or 1:50,000 rock geochemical anomalies on the surface.

[0035] 3) Elements for classifying magmatic stages of igneous rocks: systematically collect magmatic rock samples in the target area, including various magmatic rocks produced in the form of vein rocks; conduct diagenetic chronology tests and use isotope dating methods such as zircon U-Pb dating to determine the timing of magmatic activity; classify the time series of magmatic activity and establish a magmatic activity stage model.

[0036] 4) Petrogeochemical data elements. This method is based on the complete analysis of major elements and trace and rare earth element analysis data of whole-rock petrogeochemical data. Therefore, on the basis of systematic sampling, 13 petrogeochemical silicate whole-rock analyses should be carried out in accordance with relevant specifications, including trace element and rare earth element analysis of elements such as Nb, Ta, Sr, and Y.

[0037] 2. Sample collection and data analysis requirements: This method is based on zircon U-Pb age data, whole-rock geochemical major element analysis data, and trace and rare earth element analysis data; it conducts temporal division, attribute differentiation, and evolutionary pattern discrimination of magmatic activity in the target area, and identifies the characteristic elements and evolutionary trends of magmatic rock assemblages with mineralization properties during the magma evolution process.

[0038] 1) Sample Collection: Rock samples are collected according to the target area. Samples are igneous rocks obtained within the target area, including various types of dike rocks. Samples are outcrop blocks and drill cores. They should be fresh rocks without signs of alteration or weathering. The sampling mass for geochemical samples should be greater than 500g, and the sample mass for zircon U-Pb dating should be 2-5kg. The sampling mass is determined by the acidic or basic nature of the rock.

[0039] 2) Sample processing: Zircon U-Pb dating samples were processed according to the requirements of artificial heavy sand treatment. After the sample crushing (including coarse and fine crushing) and separation (including washing, magnetic separation, gravity separation and manual selection), single zircon crystals were selected, embedded in epoxy resin and polished for target preparation. Cathodoluminescence (CL) imaging technology was used to examine the internal structure of the zircon, and the appropriate location for micro-area in situ zircon U-Pb dating was determined. The number of single zircon crystals should meet the requirement of >15 valid data points.

[0040] Rock and geochemical samples: Use a pollution-free sample crusher to prepare whole-rock powder samples. Process the samples through coarse, medium and fine crushing. The sample size should reach 200 mesh, and the mass of the sample after reduction should be >150g.

[0041] 3) Sample analysis methods and quality requirements: Zircon U-Pb isotope dating analysis: Laser ablation plasma mass spectrometry (LA-ICP-MS or LA-MC-ICP-MS) or high-resolution secondary ion probe mass spectrometry (SHRIMP) can be used.

[0042] Taking laser ablation-multi-acceptor plasma mass spectrometry as an example, the instruments used were Neptune Plus MC-ICP-MS (Thermo Fisher Scientific) and Geolas Pro excimer ArF laser ablation system (Coherent). In the ablation chamber, helium was used as the carrier gas and argon was used as the supplementary gas. The Geolas Pro excimer ArF laser ablation system included a "line" signal smoothing device that ensured signal stability even at laser repetition rates as low as 1 Hz. The laser ablation energy density was 2.5–5 J / cm -2 The beam size and frequency were 24 µm and 2 Hz, respectively. Zircon 91500 was used as an external standard for U-Pb dating. Each analysis consisted of 10 seconds of background acquisition and 40 seconds of sample data acquisition. Data analysis was performed using ICPMSDataCal 10.7, including background and signal integration, drift correction, and quantitative calibration. Concordia plots and weighted averages were calculated using Isoplot 18. The magma emplacement time was statistically calculated based on the 15 youngest ages of inherited zircons.

[0043] Rock geochemical analysis: Whole rock major element analysis items: SiO2, Al2O3, TFe2O3, CaO, MgO, K2O, Na2O, P2O5, TiO2, MnO and H2O - 、H2O + and 13 items of LOI; among them, the analysis of major elements SiO2 and LOI was carried out by gravimetric method, and the analysis of TFe2O3, CaO, MgO, K2O, Na2O, P2O5, TiO2, and MnO was carried out by inductively coupled plasma atomic emission spectrometry.

[0044] Specific method based on: GB / T 14506.30-2010 Chemical analysis methods of silicate rocks Part 30: Determination of 44 element quantities.

[0045] GB / T 14506.3-2010 Chemical analysis methods of silicate rocks Part 3: Determination of silicon dioxide content.

[0046] GB / T 14506.32-2019 Chemical Analysis Methods for Silicate Rocks Part 32: Determination of 20 Components including Aluminum Oxide, Mixed Acid Decomposition-Inductively Coupled Plasma Atomic Emission Spectrometry.

[0047] Trace and rare earth element analysis items: should include Nb, Ta, Sr, and Y. Trace and rare earth element analysis is performed using inductively coupled plasma mass spectrometry.

[0048] Specific method is based on: GB / T 14506.30-2010.

[0049] The analysis error of main elements is within 1%. For trace elements, the accuracy is better than 3% when the concentration is above 10×10-6, and the accuracy is better than 3% when the concentration is below 10×10 -6 The following have an accuracy better than 10%.

[0050] 3. Methods and steps for mineralization judgment.

[0051] 1) Classification of magmatic system stages: First, the time of magmatic intrusion is determined based on zircon U-Pb age data, and the magmatic activity stages (magmatic stages) are divided.

[0052] Secondly, if Figure 1 As shown in the silica-alkali diagram (W(SiO2)-W(K2O+Na2O)), component points are cast for igneous rocks of different time sequences, distribution pattern diagrams of igneous rocks of different periods are established, and component end members of igneous rocks of different periods are divided.

[0053] Third, based on the basicity and total alkali content of igneous rocks, the authors determined that within the same magma system, two or more component end-members coexist: basic, acidic, and alkaline. This study also clarified that within the igneous rock assemblage of the same period, there exists a magma evolutionary basis characterized by magma mixing, with basic and acidic end-members at the two poles, with the alkaline end-member being absent. The evolutionary process of magma with mineralization properties manifests as mixing of basic and acidic magma, with the simultaneous derivation of alkaline and acidic magma to form the alkaline end-member. This demonstrates the existence of the fundamental characteristics of magma mixing, the characteristics of magma end-members, and the magma evolutionary model of the composition, pathways, and products of magma mixing end-members.

[0054] 2) Determination of magma origin, evolution pattern and properties: First, Figure 2 As shown in the figure, the W(Nb / Ta)-W(SiO2) diagram is used to judge the rock component projection and combination distribution pattern of the same sequence of igneous rocks. The igneous rock combination with mineralization potential presents the following characteristics: the igneous rock combination with component end-member characteristics, with Nb / Ta as the indicator, shows that it originated from the crust or mantle source; other rock samples of the same period are distributed between the crust-derived and mantle-derived magma end-members, forming a component transition zone with the crust and mantle sources as the starting and ending points; indicating the existence of a mixture of shell and mantle components with Nb / Ta as the indicator.

[0055] Secondly, if Figure 3As shown in the figure, a unified sequence of igneous rock components is projected in the W(Sr / Y)-W(Y) diagram to identify the genetic environment and evolutionary trend of the igneous rocks. The existence of adakite indicates that the origin of the magma is inconsistent melting (partial melting) driven by tectonic movements such as plate subduction or thickening of the lithosphere; the existence of magmas with different genetic types and properties lays the foundation for magma mixing; the igneous rock assemblage with mineralization potential shows a continuous distribution feature from the adakite magmatic rock area to the volcanic arc magmatic rock area, which is manifested by the existence and mixing of different types of magma formed by inconsistent melting driven by tectonic movements.

[0056] Third, if Figure 4 As shown in the figure, different sequences of igneous rock assemblages are mapped in the silicon-potassium discrimination diagram (W(SiO2)-W(K2O)). The igneous rock assemblages with mineralization properties have the characteristics of evolving from the basanite series to the high-potassium calc-alkaline series and the calc-alkaline series. The mineralization properties of the magma are derived from the extraction and enrichment of mineralization elements by magmatic hydrothermal fluids caused by the mixing of high-potassium and low-calcium alkaline magma and calc-alkaline magma.

[0057] Finally, the magmatic rock combination of the same period has the above characteristics, and it is inferred that the magmatic activity in this area has the potential to form gold and polymetallic mineralization.

[0058] 3) Identification of mineralization potential areas: Based on the above judgment results, combined with the abnormal characteristics of single or multiple element combinations of gold, silver, lead, zinc, copper, molybdenum and iron obtained from regional rock geochemical measurements during geochemical exploration, it can be specifically predicted that there is a hidden mineralization system related to magmatic activity in the target area, which has the conditions for the formation of endogenous mineral deposits.

[0059] 4. Projection data processing requirements.

[0060] 1) W (Nb / Ta), W (Sr / Y), etc. are mass ratios.

[0061] 2) Data such as W(SiO2), W(K2O+Na2O), and W(K2O) should be standardized by excluding the loss on ignition. The specific calculation formula is: W(X)=X 测试值 / ∑(SiO2+Al2O3+TFe2O3+CaO+MgO+K2O+Na2O+P2O+TiO2+MnO)test value*100.

[0062] 3) Requirements for submitting images: Figure 1 The magmatic rock combination with mineralization properties can form a transition zone from the basic end member of the alkaline series to the acidic end member of the subalkaline series at the W(SiO2)-W(K2O+Na2O) projection point, indicating that the magma evolves from alkaline to subalkaline during the evolution process, and at the same time, alkaline acidic end member components can be derived. Figure 1The names of the rock types in each area are the names of two different forms of the same rock type. For example, the olivine gabbro in area number 1 is an intrusive rock, while the picrite basalt is an extrusive rock. The corresponding other area numbers are all intrusive rock names outside the brackets, and extrusive rock names inside the brackets. This rock type is named as a commonly used name in this field.

[0063] Figure 2 The combination of magmatic rocks with intermediate mineralization properties has a basic mantle-derived end member and an acidic crust-derived end member. At the same time, more samples are distributed between the mantle-derived end member and the crust-derived end member, indicating that there is a mixing process of crust and mantle magma, and the two mix to form intermediate-acidic magmatic rocks.

[0064] Figure 3 The mineralization-bearing magmatic rock assemblage is plotted along the W(Sr / Y)-W(Y) curve. Samples are distributed at the intersection of the adakite and classic arc rocks and in the adjacent transition zone, demonstrating a continuous transitional state. This suggests that the formation of mixed magmas is closely related to the tectonic environment: the adakite formation shows that intermediate-acidic magmatic rocks are formed by incongruous melting under certain pressures, while the classic arc magmatic rock group is mostly basic magmatic rocks with mantle-derived origins. This diagram indicates that mineralization occurs through the mixing of two magmas of different properties.

[0065] Figure 4 The magmatic rock combination with mineralization attributes is projected in the W(SiO2)-W(K2O) diagram. The distribution of sample points gradually transitions from the basanite series to the calc-alkaline series, indicating that there is a magma mixing process represented by different component end members in the magma evolution process. The characteristics of the evolution from the basanite series to the calc-alkaline series are actually a series of magmatic rock combinations formed by the mixing of high-potassium and low-calcium magma and calc-alkaline magma.

[0066] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0067] The technology, shape, and structure not described in detail in the present invention are all well-known technologies.

Claims

1. A rock geochemical identification method for endogenous gold and polymetallic mineral concealed mineralization systems, characterized in that: The following steps are involved: S1. Applicable conditions and data basis: Applicable conditions include four aspects: tectonic environment conditions, tectonic, magmatic and metallogenic units, magmatic stage division of igneous rocks, and rock geochemical data. The data basis includes zircon U-Pb age data, whole-rock rock geochemical analysis data, and trace and rare earth element analysis data. S2. Sample collection and data analysis requirements: Rock samples shall be collected from the target area. The samples shall be non-weathered igneous rocks obtained in the target area. The magmatic activity time sequence, attribute differentiation, and evolution pattern discrimination shall be carried out in the target area. The characteristic elements and evolution trends of the magmatic rock assemblages with metallogenic properties during the magmatic evolution process shall be identified. S3. Method for identifying mineralization system: S31. Magmatic System Stage Division: Determine the intrusion time of magmatic rocks based on zircon U-Pb age data, divide the magmatic activity stages, establish a silica-alkali map, and plot the components of magmatic rock samples according to the magmatic activity time sequence in the silica-alkali map. Establish a distribution pattern map of magmatic rocks of different stages, and divide the component end members of magmatic rocks of different time sequences. Determine the existence of two or more component end members in the same stage of magmatic evolution based on the basicity and total alkali content of the magmatic rocks. Component end members include basic end members, acidic end members, and alkaline end members. Determine that within the rock assemblage of magmatic rocks of the same time sequence, there is a magma evolution basis with basic end members and acidic end members as the two poles, and a magma mixing model, where the alkaline end member is not required. S32. Magma origin, evolution pattern and attribute judgment: Establish W(Sr / Y)-W(Y) diagram and Si-K discrimination diagram, and identify magma systems with metallogenic properties based on the diagrams: Determine whether the magma rock combination with metallogenic potential presents mixed characteristics of crust and mantle components with different indicators; Projecting the rock components of igneous rocks from the same period in the W(Sr / Y)-W(Y) diagram shows that the igneous rock assemblage with mineralization potential shows a continuous distribution from the adakite igneous rock area to the volcanic arc igneous rock area, showing the mixing characteristics of different types of magma formed by inconsistent melting driven by tectonic movement. Projecting the igneous rock assemblage from the same period in the silicon-potassium discrimination diagram shows that the igneous rock assemblage with mineralization properties has the characteristics of evolving from the basanite series to the high-potassium calc-alkaline series and the calc-alkaline series. The above characteristics of the igneous rock assemblage from the same period indicate that the magmatic system formed by the magmatic activity in this area has the potential to form gold and polymetallic mineralization. S33. Identification of mineralization potential areas: Based on the above judgment results, combined with the abnormal characteristics of single or multiple element combinations of gold, silver, lead, zinc, copper, molybdenum and iron obtained from regional rock geochemical measurements in geochemical exploration, it is predicted that there is a hidden mineralization system related to magmatic activity in the target area, which has the conditions for the formation of endogenous deposits of the above mineral species, and relevant resource exploration is carried out.

2. The rock geochemical identification method of endogenous gold and polymetallic ore concealed mineralization system according to claim 1 is characterized in that: The tectonic environmental condition elements in step S1 are specifically applicable to the tectonic environment of ocean-continent subduction and continent-continent collision formed by plate convergence. In the above environment, there is a strong crust-mantle interaction formed by the subduction of the crust and the upwelling of mantle-derived magma.

3. The rock geochemical identification method of endogenous gold and polymetallic ore concealed mineralization system according to claim 1, characterized in that: The structural, magmatic and metallogenic unit elements in step S1 are that the target area should be located in a metallogenic sub-region or ore field in the five-level metallogenic unit classification system and be a potential structural, magmatic and metallogenic distribution zone. The specific characteristic elements include the following three contents: (1) There are fault structures that cut through the lithosphere in the target area, which are characterized by the presence of strike-slip faults or strike-slip fault bundles, dike groups, and rock stock-like rock bodies, that is, the existence of a tectonic-magmatic activity zone; (2) Rock stocks or dike groups with crust-mantle mixing characteristics are distributed along the tectonic-magmatic activity belt; (3) The presence of primary mineralization of gold, polymetallic materials, etc. or corresponding 1:200,000 or 1:50,000 rock geochemical anomalies on the surface.

4. The rock geochemical identification method of endogenous gold and polymetallic ore concealed mineralization system according to claim 1, characterized in that: The elements for dividing the magmatic rock into magmatic stages in step S1 are to systematically collect magmatic rock samples in the target area, including various magmatic rocks produced in the form of vein rocks, carry out diagenetic chronology testing, use isotope chronology to determine the time of magmatic activity, such as the zircon U-Pb dating method, divide the magmatic activity time sequence, and establish a magmatic activity stage model.

5. The rock geochemical identification method of endogenous gold and polymetallic ore concealed mineralization system according to claim 1, characterized in that: The rock geochemical data elements in step S1 are based on the whole rock geochemical analysis and trace element and rare earth element analysis data. Therefore, on the basis of systematic sampling, the rock geochemical whole rock analysis should be carried out according to the corresponding specifications, including the whole rock analysis of silicate major elements, including: SiO2, Al2O3, TFe2O3, CaO, MgO, K2O, Na2O, P2O5, TiO2, MnO and H2O - 、H2O + The analysis of major elements SiO2 and LOI was conducted by gravimetric method, TFe2O3, CaO, MgO, K2O, Na2O, P2O5, TiO2 and MnO were conducted by inductively coupled plasma atomic emission spectrometry, and trace elements and rare earth elements, including Nb, Ta, Sr and Y, were analyzed.

6. The rock geochemical identification method of endogenous gold and polymetallic ore concealed mineralization system according to claim 1, characterized in that: The sample collection in step S2 includes: collecting rock samples from the target area; the samples are igneous rocks available in the target area, including various types of vein rocks; the samples are outcrop blocks and drill cores; the samples should be fresh rocks without alteration and weathering characteristics; the sampling mass of geochemical samples should be greater than 500g; the sampling mass of zircon U-Pb dating test samples should be 2-5kg, and the sampling mass should be determined based on the acidity or basicity of the rock. Zircon U-Pb dating sample processing involves the following steps: Single zircon crystals are selected through sample crushing and separation according to artificial heavy sand treatment requirements; these selected zircon crystals are embedded in epoxy resin and polished for target preparation; cathodoluminescence (CL) imaging is used to examine the zircon's internal structure and determine the appropriate location for in situ zircon U-Pb dating, with the goal of determining the last date of magmatic activity. The number of single zircon crystals required to generate at least 15 valid data points is sufficient for statistical analysis. Processing of rock geochemical test samples: Use a pollution-free sample crusher to prepare whole rock powder samples, and process the samples through coarse crushing, medium crushing and fine crushing. The sample particle size should reach 200 mesh, and the mass of the sample after reduction should be >150g.

7. The rock geochemical identification method of endogenous gold and polymetallic ore concealed mineralization system according to claim 1, characterized in that: The alkaline end member in step S31 is not required to be a magma evolution process with mineralization properties, which is manifested as a mixture of basic magma and acidic magma, and at the same time, alkaline acidic magma is derived to form alkaline end members; it shows the existence of basic characteristics of magma mixing, magma end member characteristics, and magma evolution patterns of magma mixing end member composition, path and products.

8. The rock geochemical identification method of endogenous gold and polymetallic ore concealed mineralization system according to claim 1, characterized in that: In step S32, the rock components of the igneous rocks of the same period are projected to identify the properties and evolution trends of the mixed igneous rocks. In the silicon-potassium discrimination diagram, the igneous rock combination with mineralization properties has the characteristics of evolving from the basanite series to the high-potassium calc-alkaline series and the calc-alkaline series. The essence of this is that the mineralization properties of the magma originate from the extraction and enrichment of mineralization elements by magmatic hydrothermal fluids caused by the mixing of mantle-derived high-potassium and low-calcium alkaline magma and crust-derived calc-alkaline magma.

9. The rock geochemical identification method of endogenous gold and polymetallic ore concealed mineralization system according to claim 1, characterized in that: The different indicators in step S32 include but are not limited to the mixing characteristics of the crust and mantle components using Nb / Ta as an indicator. The origin, evolution pattern and property judgment of the magma also establish a W(Nb / Ta)-W(SiO2) diagram, and the rock component projection and combination distribution pattern of the magmatic rock of the same period are judged in the W(Nb / Ta)-W(SiO2) diagram. The magmatic rock combination with mineralization potential presents the mixing characteristics of the crust and mantle components using Nb / Ta as an indicator. The essence of this is to judge whether the magma involved in the mixing originates from the mantle and the crust respectively; the rock component projection of the magmatic rock of the same period is performed, and the origin and magma mixing pattern of the magma of the magmatic rock combination of the same period are judged. The magmatic rock combination with mineralization potential presents the following characteristics: Magmatic rocks with component end-member characteristics, as measured by Nb / Ta, originate from crust or mantle sources. Other rock assemblages of the same period are distributed between the crust-derived and mantle-derived magma end-members, forming a compositional transition zone with the end-member components as the starting and ending points. The essence is to determine whether the mixed magma originates from the lithospheric crust and lithospheric mantle respectively.

10. The rock geochemical identification method of endogenous gold and polymetallic ore concealed mineralization system according to claim 1, characterized in that: In step S32, the rock components of the igneous rocks of the same period are projected to identify the genetic environment and evolutionary trend of the igneous rocks. The existence of adakite indicates that the origin of the magma is inconsistent melting driven by tectonic movements such as plate subduction or thickening of the lithosphere. At the same time, projection comparisons of different periods are performed. The igneous rock assemblages with mineralization potential are continuously distributed from the adakite igneous rock area to the volcanic arc igneous rock area, and are mainly concentrated in the intersection area between the adakite igneous rock area and the volcanic arc igneous rock area, showing a mixture of different types of magma formed by inconsistent melting driven by tectonic movements.

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