Ore prospecting method and system for representing water-rock reaction degree by fusing carbon and oxygen isotope gradient

Abstract

The invention discloses a prospecting method and system for representing the water-rock reaction degree by fusing carbon and oxygen isotope gradients, and belongs to the technical field of early exploration of hydrothermal deposits controlled by structures. The method comprises the following steps: determining a target area structural fracture mapping unit, performing identification and mapping by virtue of an intelligent sensing system, performing manual correction, collecting a filling cement sample, and obtaining delta 13C and delta 18O values; determining that protolith and fluid isotope form an end member, constructing a water-rock reaction degree quantitative index WRI, and performing spatial nesting on the WRI and a tectonic fracture unit to obtain water-rock reaction degree gradient spatial expression and abnormal classification; and in combination with the geological background and alteration characteristics, a hydrothermal activity center is delineated, and an ore prospecting target area is optimized by artificial intelligence. According to the method, the delta 13C and delta 18O values of the filling cement are quantitatively converted into the WRI, the prospecting method and system for representing the water-rock reaction degree by fusing the carbon and oxygen isotope gradient are constructed, high-precision positioning of the hydrothermal activity center is achieved, the concealed ore prospecting prediction capacity is remarkably improved, and the method and system are suitable for early exploration of the hydrothermal deposit controlled by the structure.

Description

Technical Field

[0001] This invention relates to the field of early exploration technology for tectonic-controlled hydrothermal deposits, specifically to a prospecting method and system that integrates carbon and oxygen isotope gradient characterization of the degree of water-rock reaction. Background Technology

[0002] Precise location and prediction of hydrothermal deposits and their deep-seated concealed ore bodies represent a major technological bottleneck in current mineral exploration. In the process of mineral prediction, traditional exploration methods generally suffer from inherent defects such as low intelligence, insufficient detection depth, and multiple interpretations of anomalies when dealing with deeply buried or poorly mineralized concealed ore bodies. Existing technical solutions tend to apply single indicators in isolation, such as inverting paleotectonic stress fields solely through the deformation structure of tectonic rocks, determining fluid sources using isotopes alone, or semi-quantitatively evaluating mineralization intensity based solely on the trace element content of tectonic rocks. While these methods have some value, they fail to systematically acquire multidimensional mineralization and prospecting information recorded by the cementation filling tectonic fractures. This results in a lack of direct and mutually corroborating evidence chains for crucial judgments regarding the migration paths of ore-forming fluids, the spatial gradient of water-rock reaction, and the location of mineralization precipitation centers, leading to unpredictable and confusing prospecting prediction results.

[0003] Practice has confirmed that ore-forming tectonic fracture zones serve as core sites for hydrothermal migration and ore deposition. The fractured rocks, porphyry, granulite, siltstone, breccia, mylonite, foliation, fault gouge, and infilling cement within these zones provide a complete record of fluid activity history. Utilizing intelligent sensing systems to identify and map the widely developed tectonic fractures in tectonically controlled hydrothermal deposits, along with carbon and oxygen isotope mapping of the infilling cement, can not only deepen our understanding of fluid origins and water-rock reaction processes but also effectively reveal the spatial variations in fluid intensity and trace dominant fluid migration pathways. This allows for the delineation of hydrothermal activity centers and the selection of potential mineralization enrichment zones. However, how to deeply couple the spatial gradient of water-rock reaction intensity revealed by carbon and oxygen isotope mapping with direct mineralization intensity to construct a quantitative methodology system from fluid tracing to target area prediction remains a pressing technical challenge. Summary of the Invention

[0004] To address the aforementioned issues, this invention provides a mineral exploration method and system that integrates carbon and oxygen isotope gradient characterization of water-rock reaction degree. By using end-member inversion under the constraint of tectonic fracture mapping units and constructing a quantitative index of water-rock reaction degree, it achieves a quantitative expression of the intensity of ore-forming fluid activity and its spatial gradient. This reveals the complete spatial gradient variation law from fluid channels to mineralization centers, providing a reliable solution to the problem of mineral exploration in tectonic-controlled hydrothermal deposits and their deep periphery, and enabling mineral geological exploration services conducted using high technology.

[0005] To achieve the above objectives, this invention provides a mineral exploration method and system that integrates carbon and oxygen isotope gradient characterization of water-rock reaction degree, specifically including the following steps: S1. Refined Division and Parameterization of Structural Fracture Mapping Units: Taking the hydrothermal mining area as the research area, based on the geological background data of the study area, through a combination of field geological reconnaissance and indoor core observation, the lithological type, structural fragmentation degree, cementation development characteristics and spatial occurrence state of the tectonic rocks in the study area are identified, and structural fracture mapping units of different levels are divided. The geological boundaries and core geological attribute knowledge maps of each unit are clarified, and a set of calculable structural attribute parameters is established for each structural mapping unit.

[0006] The set of structural attribute parameters includes at least: fracture level, tectonic rock type, degree of fracturing, filling rate of cementitious material, and width of tectonic zone, which serve as structural constraints for subsequent response intensity inversion.

[0007] S2. Construction of a Structural Fracture Mapping and Sampling Point-Tectonic Unit Binding Database: Based on the mapping units divided in S1, the intelligent sensing system for structural fractures in the study area was used to identify and map fractures at different scales (1:25,000 to 1:1,000). Geological profiles were measured through manual traversal geological surveys, and detailed records were made of the distribution area, degree of fragmentation, and color, composition, content, and degree of cementation of different types of structural fractures within each mapping unit. Contour maps of structural fractures and their cementation characteristics at specific scales were drawn using geological mapping software. Sampling points were established for the cementation development sections of each type of structural fracture, and representative samples were collected from each mapping unit. The coordinates, structural location, and sample characteristics of the sampling points were recorded. A standardized database of "sampling point-structural unit-structural attribute" was established, binding each sampling point to a unique structural fracture mapping unit and its set of structural attribute parameters, providing a unified data organization method for isotope observation and subsequent inversion calculations.

[0008] S3. Carbon and oxygen isotope testing and standardization of the cementitious filler in structural fractures: The samples collected in S2 were pretreated and prepared into dry 200-mesh samples for testing; the δ¹⁴ of the cementitious filler was measured using gas isotope mass spectrometry. 13 C and δ 18 O value, integrated test database; quality control of test data, removing data that are obviously affected by epigenetic modification or abnormal deviation; carbon and oxygen isotope data that have passed quality control are written back to the database in step S2 to form an "isotope-tectonic fracture joint database", which serves as the observation constraint input for subsequent end-member inversion and WRI calculation.

[0009] S4. Construction of the End-Member Constraint and Water-Rock Reactivity Index (WRI): Specifically, this includes background endmember determination, initial hydrothermal endmember inversion, and WRI calculation and classification.

[0010] S5, Spatial Distribution Feature Analysis Module of Water-Rock Reaction Gradient Anomaly: The WRI is associated with the spatial coordinates of each sampling point to form a discrete test point set, and then spatially overlaid with the structural fracture mapping unit, so that the WRI value of each sampling point is assigned to the corresponding structural fracture mapping unit and its structural attribute parameter set; under the constraint of the structural unit, the WRI in each unit is statistically and spatially expressed to obtain the structural constraint spatial distribution map of the water-rock reaction degree index, and further analyzes the gradient attenuation structure of WRI in the fracture core area-peripheral surrounding rock and the segmented anomaly characteristics along the fracture strike, clarifying the coupling relationship between WRI gradient anomaly and structural rock type, fracture zone and structural branch.

[0011] S6. Delineation of Hydrothermal Activity Centers and Selection and Classification of Target Areas for Deep-Front Exploration: Based on the WRI classification results, WRI gradient anomaly structure, and tectonic background constraints, hydrothermal activity centers are delineated and deep-front exploration target areas are selected using artificial intelligence classification: the carbon and oxygen isotope concentration center is the hydrothermal activity center, and areas with strong reaction levels and located in the direction of first-order tectonic extension are selected as Class A target areas; areas at the edge of strong reaction levels or medium reaction levels and located within first- or second-order tectonic zones are selected as Class B target areas; and the outer transition zone of medium or strong reaction levels is selected as Class C target areas. Target area prediction maps are compiled for drilling verification and deployment.

[0012] As a preferred embodiment of the present invention, step S4 includes the following steps: S4.1 Data Input: Read the spatial coordinates xi, structural property parameter set, and isotope test value Si=(δ) of the i-th sampling point from the isotope-structure joint database. 13 C cem, i , δ 18 O cem, i ) S4.2 Background Endmember Determination: Unaltered / weakly altered carbonate rock sample set Ωb was selected from the database, and its isotopic composition was statistically analyzed. The statistically representative value was calculated and used as the background endmember Eb=(δ 13 C b , δ 18 O b The statistical representative value is preferably the mean; when the sample distribution is skewed or contains outliers, the median or truncated mean is preferred to improve endmember stability and cross-regional comparability. The truncated mean is the mean of the remaining samples after sorting the isotope values ​​by size, removing samples from both ends by a preset truncation ratio α, where α is preferably 5% to 10%.

[0013] S4.3 Initial Hydrothermal Endmember Inversion: Since hydrothermal endmembers are difficult to collect directly, this invention uses an endmember-reaction path model to invert the isotopic observation set Ωcem of the cementitious material. The observation of the i-th cementitious sample is represented as a parameterized form along the "background endmember-fluid endmember" reaction path: in, =(δ 13 C f , δ 18 O f ( ) represents the initial ore-forming fluid end-member to be determined. This is a parameter representing the degree of water-rock reaction. This is a deviation term.

[0014] Construct the objective function based on the least squares criterion: The optimal initial ore-forming fluid end-member was obtained by solving the problem. It is used as the fluid reference endmember for subsequent WRI calculations.

[0015] S4.4 WRI Calculation and Classification: In and Once determined, the water-rock reaction degree index is calculated for each sampling point: in, The water-rock reaction degree index for the i-th sampling point is denoted by 0, and its value ranges from 0 to 1. The weighting coefficients for the contribution of carbon and oxygen isotopes to the water-rock reaction degree are 0.4 and 0.6, respectively.

[0016] δ 13 C cem, i The measured δ¹³C and δ¹ of the cementitious material filling at the i-th sampling point are respectively... 8 O value; δ 13 C b δ 13 O b The background endmembers (unaltered / weakly altered wall rocks) are composed of carbon and oxygen isotopes. δ 13 C f δ 13 O f For the initial ore-forming fluid end-members δ¹³C and δ¹ 8 The inversion determination value of O; 0.4 and 0.6 are the weighting coefficients for the contribution of carbon and oxygen isotopes to the degree of water-rock reaction, respectively.

[0017] Classification based on WRI values: WRI≥0.7 indicates a strong abnormal reaction zone, 0.4< WRI <0.7 indicates an abnormal reaction zone. WRI ≤0.4 indicates a weak reaction abnormality zone.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention introduces an isotopic reaction path inversion model under background endmember-hydrothermal endmember constraints, which continuously and quantitatively converts the carbon and oxygen isotope observations of tectonic fracture-filling cement into the water-rock reaction index (WRI), realizing the transformation of water-rock reaction degree from "qualitative identification" to "continuous quantitative characterization". Compared with traditional methods based on isotopic interval discrimination or empirical classification, this invention can perform comparable quantitative evaluation of water-rock reaction degree in different tectonic units and different spatial locations under a unified endmember reference, significantly improving the expression accuracy and identification stability of water-rock reaction information.

[0019] (2) Based on the spatial gradient characteristics of the water-rock reaction degree index (WRI), this invention reveals the spatial decay law of the water-rock reaction degree during the migration of ore-forming fluids along tectonic channels and their diffusion into the surrounding rocks, thereby establishing a prospecting criterion of "tectonic channel-reaction gradient-ore-forming indicator". This method does not rely on the direct exposure of ore bodies or shallow mineralization information, and can effectively identify the main migration channel of ore-forming fluids and its reaction concentration area in deep and concealed conditions, overcoming the problems of vague targets and insufficient directionality in the prediction of deep and concealed mineralization methods.

[0020] (3) This invention couples the spatial distribution of the water-rock reaction degree index with the structural fracture mapping unit, realizing a unified expression of water-rock reaction information and structural attributes. This elevates the delineation of prospecting target areas from a single anomaly identification to a quantitative comprehensive identification based on artificial intelligence constrained by structure. This technical approach has good operability and scalability, and is suitable for early exploration of hydrothermal deposits controlled by structure and for prospecting prediction in deep and marginal areas. It has a stable prospect for widespread application. Attached Figure Description

[0021] Figure 1 This is a flowchart of a mineral exploration method that integrates carbon and oxygen isotope gradient characterization of water-rock reaction degree according to the present invention. Figure 2Figure 11 shows the structural profile of points 97-107 along Line 11 in the study area of ​​this invention. Figure 11(a) shows the mapping and sampling points of the first and second sections of the Weining Formation of the Carboniferous strata along Line 11; Figure 12(b) shows the mapping and sampling points of the second section of the Weining Formation of the Carboniferous strata along Line 11; Figure 13(c) shows the mapping and sampling points of the second section of the Weining Formation of the Carboniferous strata along Line 11; Figure 14(d) shows the mapping and sampling points of the Qixia-Maokou Formation of the Permian strata below Line 11; Figure 15(e) shows the mapping and sampling points of the fracture zone of the Qixia-Maokou Formation of the Permian strata below Line 11; Figure 16(f) shows the mapping and sampling points of the Emeishan Basalt Formation of the Permian strata along Line 11; and Figure 17(g) shows the measured profile of points 97-107 along Line 11. Figure 3 Figure 11 is a structural profile of the research area of ​​this invention. Figure 11 shows the sampling points for the foliation zone mapping of Guanyinshan Line 11; Figure 12 shows the sampling points for the breccia-fault mapping of Guanyinshan Line 11; Figure 13 shows the sampling points for the cleavage zone-fault-lime mapping of Guanyinshan Line 11; Figure 14 shows the sampling points for the limestone-breccia-fault mapping of Guanyinshan Line 11; Figure 15 shows the sampling points for the limestone mapping of Guanyinshan Line 11; and Figure 16 shows the measured profile of Guanyinshan Line 11. Figure 4 A diagram of the δ13C-δ18O isotopes of the cementitious material used to fill the structural fractures in the study area of ​​this invention; Figure 5 This is a simulation diagram of the δ13C-δ18O isotopes of the cementitious material filling the study area of ​​this invention; Figure 6 This is a contour map of C isotopes in the study area of ​​this invention; Figure 7 This is an isotope contour map of the study area of ​​this invention; Figure 8 This is a plan view of the water-rock reaction degree gradient diagram in the study area of ​​this invention; Figure 9 This is a prediction map of the preferred mineral exploration target area for the research area of ​​this invention. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Please see Figures 1-9 This invention discloses a mineral exploration method and system that integrates carbon and oxygen isotope gradient characterization of water-rock reaction degree. The following detailed implementation process is illustrated using a deep-edge mineral exploration prediction method for a tectonic-controlled hydrothermal deposit in northeastern Yunnan as an example: The study area is located in the middle of the Yunnan-Northeast Platform Folding Belt on the southwestern margin of the Yangtze paraplatform, at the intersection of the NE-trending structure and the NW-trending structure. The tectonic activities are intense, forming a rather complex strata and tectonic framework as well as a favorable metallogenic environment. The tectonic deformation characteristics in this area are unique. To the west is the NE-trending tectonic belt, and to the east is the NW-trending tectonic belt. At the intersection of the two tectonics, they combine to form the "入"-shaped and "T"-shaped structures. Therefore, the structures in the area are complex, faults are developed, and the folds are mainly tight cuspate folds, and are damaged by faults and incomplete. The NW-trending structure develops in the middle and eastern parts and is the northern extension of the Ziyun-Yadu fault zone in western Guizhou. The strata in this zone are D 2-3 , and the overall occurrence is a monoclinic structure gently dipping southwest, with an inclination angle of 10°-20°. There are secondary folds developed, and the main body is fault structure, mainly including Fault I, Fault II, Fault III and Fault IV. The NE-trending structure is mainly composed of the DB fault, the FSC fault, and the nearly NS-trending HMZ anticline and MT syncline.

[0024] The structures in this ore deposit can be divided into two groups according to their strikes: NE-trending structures and NW-trending structures. Among them, the NE-trending structures are mainly the MMS overturned anticline, the FMB compressional-shear fault, the MP compressional-shear fault and the LZH compressional-shear fault. The three faults show an imbricate distribution in the section; the NW-trending structure is represented by the LJ fault.

[0025] The strata exposed in the mining area mainly include the middle and upper Devonian, Carboniferous, Permian and a small amount of Quaternary, lacking Ordovician and Silurian; the ore-bearing strata are mainly the Zaige Formation of the upper Devonian, the Baizuo Formation of the lower Carboniferous and the Weining Formation of the middle Carboniferous.

[0026] This ore deposit is mainly composed of Orebody Groups I, II and III. The strike of the orebody is NE-SW, the dip direction is SE or NW, and the dip angle is 60°-90°. The orebody occurs along the NE-trending interlayer fault zone, showing vein-like, lens-like, stockwork-like and stratoid shapes, and its depth extension is greater than the strike extension; it is concentrated in the plunging end of the overturned anticline and the steeply dipping strata of the NW overturned wing. In the plane and section, the orebody has obvious phenomena of pinching out and reappearing, swelling and shrinking, and the boundary between the orebody and the surrounding rock is obvious. From the shallow part to the deep part, the ore shows the change rule of oxidized ore → mixed ore → sulfide ore. The resources in this mining area are facing a crisis, and it is urgent to carry out regional prospecting and deep and marginal prospecting prediction research.

[0027] A prospecting method and system that combines carbon and oxygen isotope gradients to characterize the degree of water-rock reaction specifically includes the following steps: S1. Refined division of tectonic fracture mapping units; Field reconnaissance: Arrange 5 route profiles perpendicular to the NW-trending fault group, such as Figure 2As shown, the measured profile results of line 11 are as follows: At observation point KL95, the northern part consists of medium- to thin-bedded fine-grained calcite-altered dolomite, with calcite exhibiting a network-like vein pattern. Occurrence: NE56°∠47°NW. The southern part consists of thick-bedded fine-grained calcite-altered dolomite, with interlayer faults developing into compressional structures. Observation point KL100: This point contains gray fine-grained calcite-altered limestone. Occurrence: NW50°∠70°NE. KL101: Gray medium- to thick-bedded limestone, stratigraphic occurrence: SN∠20°E. Observation point KL102: Gray to light gray fine-grained limestone, stratigraphic occurrence: NE65°∠60°NW. Observation point KL103: Medium- to thin-bedded fine-grained limestone with well-developed cleavage zones. Stratigraphic attitude: NE60°∠60°NW, cleavage zone SN∠85°E. Observation point KL104: Lithological joint point, light gray medium-thick layered fine-grained limestone with weak calcite alteration; calcite veins are present, and two sets of joints are developed. Stratigraphic attitude: NW35°∠76°NE, j1: NE60°∠82°SE, j2: NW45°∠32°SW. Observation point KL105: Tectonic point, a breccia zone is observed, with an upper and lower interface width of approximately 15m. Angular to subangular calcited limestone is visible within the zone, cemented by calcite alteration. The breccia fragments are of varying sizes, unoriented, and unsorted. Observation point KL106 is the boundary between breccia and limestone. The breccia zone is approximately 120m wide, with the lower interface limestone attitude: NE40°∠42°SE. KL107 marks the boundary between the Emeishan basalt and the Permian Qixia Maokou Formation limestone. Point E is the Qixia Maokou Formation vein-like calcite-altered fine-grained limestone with 4-5 calcite veins per 10cm. To the west of point Emeishan basalt.

[0028] Based on the measurements of this profile, the following characteristics are observed: 1) The scale of the structures varies. The larger first-order tectonic fracture zones are more developed, while smaller second- and third-order structures can be seen in the limestone and dolomite of the hanging wall and footwall of the fault zones.

[0029] 2) Point KL105 of this section, through observation of the breccia zone, is a first-order tectonic fracture zone.

[0030] 3) Point KL85 in this section may be a thrust-nappe structure controlled by the F15 fault, and its internal structural rocks have zoning and cleavage characteristics.

[0031] 4) At point KL86 in this section, interlayer faults are relatively well-developed, suggesting a compressional structure. Its formation may be related to thrust-nappe tectonics, but it is relatively small in scale and mainly a secondary structure. The tectonic rocks are mainly breccia and siltstone, mostly cemented by argillaceous components, and the cementing material effervesces strongly when dripping acid.

[0032] 5) The scale of interlayer fractures is relatively small, and the width of the fracture zones is mostly between 3 and 10 cm. The main developments within the zones are foliated tectonic rocks and vein-like calcite-altered hydrothermal alteration.

[0033] In summary, based on the fracture scale, combination of tectonic rock types, degree of fragmentation, and filling rate of cementitious material, the tectonic fracture zone is divided into different levels of mapping units, and a set of calculable tectonic attribute parameters is established for each unit.

[0034] The core of the NW-trending F1 fault group is breccia, with a fault band of about 15m. Within the band, angular to subangular calcite limestone can be seen. The breccias are of varying sizes, poorly sorted, and non-directional. The breccias are generally rounded, strongly fractured, and widely cemented by carbonate cement. The carbonate cement filling rate is 60%, and it is classified as a "strongly fractured-strongly filled" unit. The F2 fault zone contains breccia with a grain size of 1-3 mm, which is medium-broken. The calcareous mudstone cement filling rate is 40%, and it is classified as a "medium-broken-medium-filled" unit. The background unit is a grayish-black unaltered dolomite. The rock is relatively intact, with moderate tectonic development and poor cementation. It is classified as a "background unit".

[0035] The aforementioned units are used as structural constraints for subsequent response intensity inversion, where each sampling point is bound to a unique construction mapping unit and its attribute parameters.

[0036] S2. Structural fracture mapping and systematic sample collection; By combining intelligent sensing system identification with mapping and field measurements of geological profiles at scales of 1:200 to 1:1000 in the study area, the zoning of tectonic rocks, fracture grade, and development of cementing material in different mapping units were recorded, and sampling points were set up in the cementing material development sections.

[0037] Taking a representative profile as an example, such as Figure 3As shown, the stratigraphic boundaries, structural types, and tectonic rock assemblage characteristics at different observation points are described and located. For example, observation point KL82 is a stratigraphic boundary. Point N is a gray, medium-bedded, fine-grained limestone interbedded with thin-bedded mudstone in the second member of the Datang Formation of the Carboniferous System, with an attitude of NW74°∠10°-21°NE; point S is a thin-bedded carbonaceous mudstone in the first member of the Datang Formation of the Carboniferous System. The rock is relatively broken, obliquely intersecting the strata, and exhibits basal wedging characteristics. The stratigraphic boundary attitude is NE60°∠15°NW. Observation point KL85 has a fault with a width of about 20 m and a strike of NE70°. The tectonic rocks within the fault zone are well-developed and have certain zonation, consisting of gray-black to yellowish-brown to light grayish-white thin-bedded sandstone and mudstone with extremely broken rocks, light gray to yellowish-brown granulite, gray-black to yellowish-brown carbonaceous phytochemical zones, gray-black to yellowish-brown carbonaceous phytochemical zones, and carbonaceous phytochemical zones. Locally, the rock has become siltstone. The central part is grayish-black carbonaceous schistose sandy siltstone, with lenses visible within the zone. The upper part is yellowish-brown siltstone, above which is a carbonaceous schistose zone, with thin-layered sandstone locally. At observation point KL86, dense cleavage schistose zones are developed, with straight fracture surfaces and local reversals. Within these zones are argillaceous schistose zones and breccia zones. The hanging wall lithology is fine-grained calcite-altered limestone, with well-developed inter-layer faults. The attitude is NW68°∠83°NE. At point KL87, the rock is gray massive calcite-altered medium- to thin-layered limestone. The stratigraphic attitude changes, presumed to be a fold N-wing attitude: EW∠28°N. At observation point KL88, inter-layer faults are developed, with straight fracture surfaces. Within the zone are yellowish-brown to yellowish-brown schistose rocks. Slickensides on the fracture surfaces indicate uplift in the hanging wall and subsidence in the footwall, indicating a compressional-shear fault. Through the above field measurements, the characteristics of different tectonic rock types, filling cements, and their spatial distribution patterns within the tectonic fracture zone were clarified.

[0038] During the structural fracture mapping and profile measurement process, cementitious material samples were systematically collected from structural zones with well-developed cementitious materials, totaling 450 samples. To ensure the data quality of subsequent isotope-reaction intensity inversion, the samples were selected based on their preservation status and representativeness, and 421 samples were chosen for subsequent isotope testing.

[0039] Meanwhile, a standardized database of "sampling point-tectonic unit-structural attribute" was established using sampling points as the basic unit. For each sampling point, its spatial coordinates, tectonic unit type, tectonic rock type, fracture grade, and filling rate of the cementitious material were recorded for correlation with subsequent isotope observation data.

[0040] S3. Acquisition and standardization of measured carbon and oxygen isotope data of filling cementitious materials; Based on the "sampling point-structural unit-structural property database" established in step S2, carbon isotope and oxygen isotope tests were conducted on the preferred samples for the cementation of the structural zone, and the obtained carbon isotope δ¹³C and oxygen isotope δ¹³C were compared with those of the other samples. 8 The measured values ​​of O are written into the corresponding sampling point records to form an isotope-structure joint database.

[0041] The preferred samples were dried and ground to 200 mesh using a ball mill to ensure the uniformity and repeatability of the reaction during isotope testing.

[0042] The carbon and oxygen isotope composition of the cementitious filling samples was analyzed by gas isotope mass spectrometry, and the δ¹⁸O values ​​were obtained. 13 C and δ 18 The measured value is obtained by using the same experimental conditions and standard substances to calibrate the same batch of samples during the test, in order to reduce the systematic deviation between different samples and ensure that the test results are comparable between different building units.

[0043] The obtained δ¹³C and δ¹ 8 The measured values ​​of O are used for quality control, and sample data that are obviously affected by epigenetic modification or abnormal deviation are removed. The isotope data that have passed the quality control are associated with the spatial coordinates and tectonic unit attributes of the corresponding sampling points and written into the isotope-tectonic joint database.

[0044] The isotopic data in the database serves as the observational constraint input for subsequent calculation of the water-rock reaction degree index and spatial inversion, providing basic data support for the quantitative characterization and gradient reconstruction of the water-rock reaction degree within tectonic fractures.

[0045] S4. Construction of the End-Member Constraint and Water-Rock Reactivity Index (WRI); Specifically, the following steps are included: S4.1 Data Input: Read the observation and structural properties of each sampling point i from the "isotope-structure joint database" formed in step 3: Spatial coordinates: x i =(x i , y i ); Structural fracture element properties: structural element type, fracture grade, filling rate of cementitious material, etc.; Measured carbon and oxygen isotope values: δ¹³C of tectonic fracture filling cement cem, i ,δ¹ 8 O cem , i : refers to the measured carbon and oxygen isotope composition of the filling cement, which is the direct observation value of this invention.

[0046] Background element (surrounding rock): δ¹³C b ,δ¹8 O b Initial hydrothermal endmember: δ¹³C f ,δ¹ 8 O f .

[0047] S4.2 Background End-Member Determination Module; Background endmembers are used to characterize the initial isotopic state of surrounding rocks in the study area where no or only very weak water-rock reactions have occurred, serving as a "zero-reaction reference" for the reaction intensity index.

[0048] 1) Sample set selection: Select background endmember sample sets Ω of "unaltered / weakly altered carbonate rocks" from the database. b The criteria for discrimination can be petrographic / field description. The criteria for discrimination of the sample set include, but are not limited to: petrographic and field description showing no obvious hydrothermal infill; no significant calcite veins or hydrothermal infill cement; no strong dissolution recrystallization or secondary cementation; and consistency with the background surrounding rock unit defined in the tectonic unit division.

[0049] 2) Calculation of statistical representative value: For the background endmember sample set Ω b The carbon and oxygen isotope compositions were statistically analyzed to calculate their ranges and representative values, and the representative values ​​were used as the background endmember isotope reference values. Where, stat{ The arithmetic mean is preferred; when outliers or significant skewness exist in the sample set, the median or truncated mean is preferred to improve the stability and cross-regional comparability of the background endmember. In the embodiment, unaltered dolomite is used as the background endmember, and its isotopic composition statistical results are as follows: δ 13 C ranges from -7.74‰ to 4.03‰, with a statistical mean of -1.61‰; δ 18 The range of O was 23.14‰ to 30.15‰, with a statistical mean of 25.15‰. (The last part, "δ," appears to be incomplete and lacks context.) 13 C-δ 18 O diagram ( Figure 4 In the unaltered dolomite (background value), δ 13 C and δ 18 The O values ​​are all within the range of marine carbonate rocks, indicating that they are of sedimentary origin.

[0050] S4.3, Initial Ore-forming Fluid End-member Inversion Module; 1) The initial hydrothermal endmember is used to characterize the initial isotopic composition of the fluid that enters the tectonic channel and dominates the precipitation of cementitious material, serving as a reference endmember for the water-rock reaction reaching a "fully fluid-controlled state." Since fluid endmembers are usually difficult to collect directly, this invention uses an endmember-reaction path inversion method to determine them.

[0051] The inversion model assumes that the isotopic composition of the cementitious material filling the tectonic fractures is the isotopic composition of the combined products of the rock reaction between the ore-forming fluid and the surrounding rock in the tectonic channel; on a macroscopic scale, the isotopes of the cementitious material in the δ¹⁴ Ω·cm region are... 13 C-δ 18 In O-space, the evolution trend is from background endmembers to hydrothermal endmembers. Based on this, the cementation infill observations are expressed in endmember path parameterization form: Based on the above mechanistic constraints, the isotopic observations of the i-th filled cement sample are expressed in a parameterized form along the endmember reaction path: in: in, δ represents the measured isotopic composition of the i-th cementitious sample; 13 C cem, i The measured carbon isotope composition of the cementitious material filling the i-th sampling point; δ 18 O cem, i The measured value of the oxygen isotope composition of the cement filling material at the i-th sampling point; Background endmembers, including δ 13 C b δ 18 O b Indicates background values ​​of carbon and oxygen isotope composition of the surrounding rocks; For the initial hydrothermal endmember, its corresponding δ¹³C f With δ¹ 8 O f These represent the initial carbon and oxygen isotopic states of the ore-forming fluids that entered the tectonic channel and dominated the precipitation of cementitious materials before the water-rock reaction occurred. ∈[0,1] represents the water-rock reaction process parameter, indicating the relative position of the cement in the "background endmember-hydrothermal endmember" reaction path; This is a deviation term used to comprehensively characterize the effects of non-ideal factors such as the superposition of multiple fluid phases, exchange in open systems, and differences in temperature fractionation.

[0052] 2) Objective function and numerical inversion Sample set of filling cementitious materials after S3 quality control , representing the set of tectonic fracture-filling cement samples participating in the water-rock reaction inversion calculation. This set is derived from the quality-controlled isotopic samples of the cement filling material in step 3. The sum of squared residuals between the observed values ​​and model predictions of all cement filling samples in isotopic space is calculated, as shown in the following expression: Where each i∈ This indicates a valid cementitious sampling point. Isotopic composition test value of the i-th filling cement sample; Background end-member (surrounding rock end-member); This is the initial hydrothermal end member; These are parameters related to the water-rock reaction process.

[0053] Since the carbon and oxygen isotope composition of the cementing material is a result of hydrothermal dissolution of marine carbonate rocks, the δ¹⁸O content of the cementing material filling the tectonic fractures is... 13 C varies from -7.60‰ to 1.26‰, with a mean of -0.73‰; δ 18 The eosinophilic morphology (O) ranges from 8.82‰ to 22.83‰, with an average of 18.41‰. During the inversion process, the search range for Ef can be reasonably limited by combining the regional metallogenic geological background and isotopic mapping results to improve the stability and physical rationality of the numerical solution.

[0054] 3) Results of hydrothermal end-member determination Through the above endmember-reaction pathway inversion calculation, with known background endmembers... Under constraints, least-squares optimization was performed on the observation set of isotopic composition of the filling cement to obtain the optimal initial hydrothermal endmember. .

[0055] This inversion result corresponds to δ¹³C-δ¹ 8 In space O, the optimal convergence point of the water-rock reaction path under various temperatures and different R / W conditions, such as... Figure 7 As shown, the initial hydrothermal isotopic composition characterizes the initial hydrothermal isotope composition that enters the tectonic channel and dominates the precipitation of cementitious material.

[0056] In this embodiment, the initial hydrothermal endmember obtained by inversion is: δ¹³C= 0.5‰, δ¹ 8 O = +9.5‰.

[0057] S4.4 Calculation and classification of the water-rock reactivity index (WRI); Based on the determination of the background endmember and the initial hydrothermal endmember, each sampling point is filled with cement. Based on the measured values ​​of its carbon and oxygen isotope composition, the corresponding water-rock reactivity index (WRI) is calculated according to the water-rock reactivity index calculation formula described in steps S4.2 to S4.3.

[0058] in, δ is the water-rock reaction degree index for the i-th sampling point, with a value ranging from 0 to 1; 13 C cem, i and δ 18 Ocem, i The measured values of δ¹³C and δ¹ 8 O of the cementitious material filled at the i-th sampling point respectively; δ 13 C b and δ 13 O b are the statistical representative values of δ¹³C and δ¹ 8 O of the unaltered / weakly altered wall rock at the background end member respectively; δ 13 C f and δ 13 O f are the inversion determined values of δ¹³C and δ¹ 8 O of the initial hydrothermal end member respectively; 0.4 and 0.6 are the weight coefficients of the contributions of carbon and oxygen isotopes to the water-rock reaction respectively; δ¹³C and δ¹ 8 O are carbon isotope and oxygen isotope respectively. For the convenience of subsequent spatial analysis and anomaly identification, the degree of water-rock reaction is classified according to the calculated WRI value, specifically: When WRI ≥ 0.7, it is determined as a strong water-rock reaction anomaly area; When 0.4 < WRI < 0.7, it is determined as a medium water-rock reaction anomaly area; When WRI ≤ 0.4, it is determined as a weak water-rock reaction area or background area.

[0059] The WRI and its classification results are used as the basic input parameters for subsequent spatial distribution analysis of the degree of water-rock reaction, delineation of hydrothermal activity centers, and optimization of ore prospecting target areas.

[0060] S5. Spatial analysis of the gradient anomaly of the degree of water-rock reaction, delineation of hydrothermal activity centers, and optimization of ore prospecting target areas; S5.1. Spatial expression of the water-rock reaction degree index under the constraint of tectonic units; The water-rock reaction degree index WRI calculated in S4.4 is associated with the spatial coordinates of the corresponding sampling points to form a discrete observation point set of the water-rock reaction degree index with sampling points as the basic units.

[0061] On this basis, the constraint of tectonic units is introduced. According to factors such as fracture scale, tectonite type combination, tectonic fragmentation degree, and filling rate of cementitious materials, the tectonic belts in the study area are divided into tectonic fracture mapping units of different levels. A computable set of tectonic attribute parameters and a knowledge graph are established for each tectonic fracture mapping unit. The parameter set and the knowledge graph at least include: fracture level, tectonite type, fragmentation grade, filling rate of cementitious materials, and width of tectonic belts, etc.

[0062] The WRI discrete observation point set is spatially overlaid with the structural fracture mapping unit, so that the WRI value of each sampling point is assigned to the corresponding structural unit, thereby realizing the spatial mapping of "WRI point attribute - structural unit surface attribute".

[0063] Subsequently, the assigned WRI data was imported into geoscientific mapping and GIS software such as MapGIS, Origin, and Surfer. Under the constraints of tectonic units, the WRI discrete values ​​were spatially expressed and visualized to generate a tectonic constraint spatial distribution map of the water-rock reaction degree index.

[0064] S5.2 Coupled analysis of tectonic properties and water-rock reaction gradient; Based on the spatial distribution map of WRI constrained by tectonic units, statistical analysis is performed on the WRI values ​​within each tectonic mapping unit to calculate their average value, maximum value, and gradient variation characteristics, thereby obtaining the characteristics of water-rock reaction degree at different tectonic unit scales.

[0065] Comparative analysis revealed that high WRI values ​​are mainly concentrated in the intersection of primary tectonic fracture zones and their derived secondary structures, and have a clear spatial correspondence with highly fractured tectonic rock types such as breccia and cataclastic rocks, as well as sections with high cementation rates. The WRI values ​​decrease from the core area of ​​the tectonic fracture zone to the surrounding rocks, forming a clear gradient zone of water-rock reaction intensity.

[0066] The gradient distribution reflects the spatial attenuation process of the ore-forming fluid reacting with the surrounding rock during its migration along the tectonic channel, providing a direct basis for identifying the main migration channel and reaction concentration area of ​​the ore-forming fluid.

[0067] S5.3 Delineation of hydrothermal activity centers and selection of prospecting target areas based on the gradient of water-rock reaction degree; By combining the water-rock reaction index classification results of S4.4 with the tectonic attribute-WRI gradient coupling characteristics of S5.2, the regional and deep-edge hydrothermal activity centers of the study area are delineated under the constraints of the tectonic background, and the prospecting target areas are selected by artificial intelligence classification.

[0068] The criteria for selecting optimal mineral exploration target areas are as follows: Grade A prospecting target area: Located in the direction of the extension of the first-level structure, with a high degree of structural fragmentation, a large cement filling rate, and corresponding to the WRI strong reaction level area, it is a concentrated area of ​​long-term activity of ore-forming fluids and strong water-rock reaction, and is the area with the greatest prospecting potential. Class B mineral exploration target areas: located at the edge of the primary tectonic fracture zone or within the secondary tectonic zone, corresponding to the WRI medium reaction level area, and have certain mineralization potential; Grade C mineral exploration target area: Located in the outer transition zone of medium or strong reaction level areas, it can serve as a potential mineral exploration area for further verification.

[0069] After completing the AI-based target area selection, a mineral exploration target area prediction map is compiled to clarify the spatial scope and priority order of target areas at all levels, providing a basis for deep drilling verification and exploration deployment.

[0070] III. Implementation Results Verification Based on the water-rock reaction index (WRI) inversion and tectonic constraint spatial analysis method constructed in steps 4-5 of this invention, the implementation effect in the study area was verified.

[0071] (1) Verification of spatial consistency between WRI anomalies and master structure; Constructing cementitious δ 13 C、δ 18 O isotope data were converted into the water-rock reactivity index (WRI) in step 4 and spatially expressed, such as... Figure 6 and Figure 7 As shown, the results indicate that the WRI strong reaction anomaly zone is spatially highly consistent with the distribution trajectory of the NW-trending first-order fault in the study area.

[0072] This primary fault, exceeding 5 km in length and 10 m in width, is structurally fractured and contains abundant breccia and carbonate cement, serving as the main tectonic channel for ore-forming fluid migration and mineralization enrichment. The WRI anomaly is continuously distributed along the fault strike; where the fault orientation changes from NW to SN, the area of ​​high WRI values ​​significantly expands, forming a concentrated zone of strong reaction anomalies covering approximately 0.8 km².

[0073] The above results verify that the WRI index constructed in this invention can effectively characterize the spatial concentration area of ​​water-rock reaction degree during the migration of ore-forming fluids along the main control fault.

[0074] (2) Verification of WRI gradient structure and fluid diffusion process like Figure 8 As shown, the WRI anomaly exhibits a spatially ring-shaped gradient structure with the NW-oriented fracture as the core and gradually decreasing towards the periphery: the core area of ​​the fracture zone corresponds to the strong WRI reaction level region, and its periphery successively transitions to the medium and weak reaction level regions.

[0075] This gradient structure clearly reflects the spatial process of gradual attenuation of the water-rock reaction degree as the ore-forming fluid migrates along the tectonic channel and diffuses into the surrounding rock. This feature indicates that WRI can not only identify anomalous locations but also quantitatively express the spatial gradient changes in the water-rock reaction degree, which is superior to single isotope anomaly identification methods.

[0076] (3) Verification of WRI concentration centers and ore-forming fluid migration direction Further analysis shows that the lines connecting the WRI strong reaction anomaly concentration centers are generally distributed in an NW direction, which is completely consistent with the strike of the NW-trending first-order fault, and the length of the connecting lines is highly matched with the effective mineralization migration section of the fault.

[0077] The results verify that the WRI spatial distribution obtained by the method of the present invention can effectively indicate the dominant migration direction of ore-forming fluids and the multi-level reaction centers formed along the tectonic channels.

[0078] (4) Verification of WRI segmentation anomalies and construction branch control Along the NW-trending fault from east to west, the WRI anomaly exhibits a regular alternating distribution of "high value-low value-high value", with anomaly segment spacing of approximately 1.2–1.5 km, which is highly consistent with the equidistant distribution of the NW-trending structures in the study area.

[0079] Geological surveys indicate that at the intersection of the NW-trending primary fault and secondary and tertiary faults, the tectonic space expands, the residence time of ore-forming fluids is prolonged, and the water-rock reaction is enhanced, corresponding to the formation of a WRI high-reaction anomaly segment; while in the straight section of the main fault, the fluid migration speed is fast and the water-rock reaction is relatively weak, corresponding to the formation of a WRI low-reaction zone.

[0080] This phenomenon further verifies that the WRI gradient anomaly can effectively respond to the control of tectonic branches on the migration and reaction intensity of ore-forming fluids.

[0081] (5) Verification of prediction effect of deep edge prospecting target area Based on the WRI gradient anomaly characteristics and structural constraints, and according to the mineral exploration target classification criteria proposed in this invention, the following areas were delineated: Figure 9 The three-level mineral exploration target area is shown.

[0082] There are two Class A prospecting target areas, located in the central and southwestern parts of the mining area, with areas of 0.8 km² and 1.2 km² respectively. Both are located in the densely developed first-order tectonic zone, corresponding to the WRI strong reaction level area, and the inferred ore body burial depth is 500-800 m. The Class B prospecting target area is located on the periphery of the Class A target area, corresponding to the WRI strong-to-medium reaction level area. The Class C prospecting target area is located on the edge of the tectonic zone, corresponding to the WRI medium reaction level to weak reaction level transition zone.

[0083] The results show that the method of the present invention can effectively classify and optimize mineral exploration target areas under the condition of deep and hidden edges, and significantly improve the pertinence and reliability of mineral exploration prediction.

[0084] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications or substitutions can be made to the above embodiments without departing from the principles and spirit of the present invention, and the scope of protection of the present invention shall be determined by the appended claims and their equivalents.

Claims

1. A mineral exploration method that integrates carbon and oxygen isotope gradient characterization of water-rock reaction degree, characterized in that, Includes the following steps: S1. Refined Subdivision Module for Structural Fracture Mapping Units: In the exploration area of ​​hydrothermal deposits controlled by tectonics, based on field geological reconnaissance and core drilling observation, intelligent sensors are used to identify the type of tectonic rocks, the degree of tectonic fragmentation, and the development characteristics of filling cement within the tectonic fracture zone. According to the fracture scale, tectonic rock assemblage, degree of fragmentation, and characteristics of filling cement, tectonic fracture mapping units of different scales are divided, and corresponding sets of tectonic fracture attribute parameters are established. S2, Structural fracture mapping and systematic acquisition module of filling cement sample: Under the constraints of the structural fracture mapping unit, the module completes the identification and mapping of structural fractures at the required specific scale using the intelligent sensing system, supplemented by geological survey correction using the manual traversal method, and systematically samples the filling cement in the structural fracture mapping. At the same time, it describes the macroscopic information of the color and composition of the filling cement and records the spatial coordinates of the sampling points and the attributes of the structural fracture mapping unit to which they belong. S3. Carbon and oxygen isotope composition analysis module for filling cement: This module preprocesses and prepares the collected structural fracture filling cement samples, analyzes their carbon and oxygen isotope composition, and obtains the measured δ¹³C and δ¹³C values ​​for each sample point. 8 O value; S4. Construction module for water-rock reactivity index under end-member constraints: In δ¹³C and δ¹³C 8 In the O diagram, the carbon and oxygen isotope composition of unaltered or weakly altered carbonate rocks is used as the background end-member, and the fluid carbon and oxygen isotope composition determined by numerical simulation or inversion is used as the hydrothermal end-member. Based on the measured carbon and oxygen isotope values ​​of the filling cement, a quantitative model of the water-rock reactivity index (WRI) is constructed, and the WRI corresponding to each sampling point is calculated. S5. Spatial Distribution Feature Analysis Module of Water-Stone Reaction Gradient Anomaly: The WRI is associated with the spatial coordinates of the sampling points and the structural fracture mapping unit to generate a spatial distribution map of the water-rock reaction degree index, identify strong, medium and weak water-rock reaction degree gradient anomaly areas, and analyze their spatial coupling relationship with the structure. S6. Hydrothermal activity center delineation and mineral exploration target area selection module: Based on the spatial distribution characteristics of the gradient anomaly of water-rock reaction degree and its overlay relationship with the results of tectonic fracture mapping, combined with the geological background (strata-lithology) and alteration characteristics, hydrothermal activity centers are delineated, and mineral exploration target areas are selected by artificial intelligence.

2. The mineral exploration method according to claim 1, which integrates carbon and oxygen isotope gradient characterization of water-rock reaction degree, is characterized in that, In S1, the division criteria for the structural fracture filling unit specifically include: 1) Tectonic rock types, including breccia, porphyry, granulite, siltstone, breccia, mylonite, foliated rock, and fault gouge; 2) The scale of the fracture zone is divided according to the width of the fracture zone: ≥0.5m is the first-level fracture zone, 0.1~0.5m is the second-level fracture zone, and ≤0.1m is the third-level fracture zone; 3) Based on the differences in the cementing materials used to fill structural fractures, the types of cementation are classified as siliceous cement, carbonate cement, and argillaceous cement. 4) Degree of bonding, classified as strong bonding, medium bonding, and weak bonding.

3. The mineral exploration method according to claim 1, which integrates carbon and oxygen isotope gradient characterization of water-rock reaction degree, is characterized in that, In S2, during the mapping and cementation sample collection process, the sampling points need to cover the known mineralization center, mineralization halo, and surrounding non-mineralized areas in order to obtain a complete isotopic geochemical spatial variation sequence.

4. The mineral exploration method according to claim 1, which integrates carbon and oxygen isotope gradient characterization of water-rock reaction degree, is characterized in that... In S4, the expression for the WRI (Water-Rock Reaction Index) quantification formula is as follows: in, δ is the water-rock reaction degree index for the i-th sampling point, with a value ranging from 0 to 1; 13 C cem, i and δ 18 O cem, i δ¹³C and δ¹⁸C of the cementitious material filling the i-th sampling point are respectively 8 O measured value; δ 13 C b and δ 13 O b The δ¹³C and δ¹³C of the unaltered / weakly altered background endmembers are respectively... 8 The statistical representative value of O; δ 13 C f and δ 13 O f These are the initial hydrothermal endmembers δ¹³C and δ¹, respectively. 8 The inversion determination value of O; 0.4 and 0.6 are the weighting coefficients for the contribution of carbon and oxygen isotopes to the water-rock reaction, respectively.

5. A mineral exploration method for characterizing the degree of water-rock reaction by incorporating carbon and oxygen isotope gradients according to claim 1, characterized in that, In S5, the gradient change of the water-rock reaction degree is as follows: According to WRI Value classification into tiers: WRI ≥0.7 indicates a strong abnormal reaction zone, 0.4< WRI <0.7 indicates an abnormal reaction zone. WRI ≤0.4 indicates a weak reaction abnormality zone.

6. The mineral exploration method according to claim 1, which integrates carbon and oxygen isotope gradient characterization of water-rock reaction degree, is characterized in that, In S6, the criteria for delineating hydrothermal activity centers and selecting prospecting target areas are as follows: first, delineating areas with strong water-rock reaction anomalies and tectonic overlap areas; second, delineating areas with medium water-rock reaction anomalies; and finally, delineating areas with weak water-rock reaction anomalies. Combining the geological background of stratigraphy-lithology-structure and alteration characteristics of knowledge graphs, prospecting target areas are selected through artificial intelligence-based hierarchical optimization.

7. A mineral exploration method for characterizing the degree of water-rock reaction by incorporating carbon and oxygen isotope gradients according to claim 6, characterized in that, The specific criteria for classifying and selecting mineral exploration target areas using artificial intelligence are as follows: Class A target areas are areas with strong reaction anomalies and areas where the main structure, ore-bearing strata, and strong alteration overlap; Class B target areas are areas with medium reaction anomalies and areas where the secondary structure, favorable lithology, and weak alteration overlap; and Class C target areas are areas with medium reaction anomalies and areas where weak alteration overlap.

8. A mineral exploration system that integrates carbon and oxygen isotope gradient characterization of water-rock reaction degree, characterized in that, This method is used to perform a mineral exploration method for characterizing the degree of water-rock reaction by incorporating carbon and oxygen isotope gradients, as described in any one of claims 1-7.

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