Method for positioning hydrothermal center of porphyry deposit

Abstract

The invention relates to the technical field of mineral exploration, and particularly provides a method for positioning a hydrothermal center of a porphyry deposit, which comprises the following steps: firstly, systematically collecting a rock sample containing epidote in an exploration area; secondly, analyzing the contents of Fe, Al, As, Sb, B, Mn, Pb and Sr elements of epidote in the sample; then, the data are matched and compared with a preset epidote geochemical fingerprint model, the model represents the rule that the contents of the eight elements change along with the distance to the center of the hydrothermal solution, and the model is established based on inversion of sampling data of a known ore deposit; and finally, determining the central position of the hydrothermal solution according to a comparison result. By applying the multi-element quantification model, the defects that a traditional method depends on a single index and is large in error are overcome, the positioning precision can be remarkably improved to the range of 50-120 m, and therefore exploration engineering is accurately guided, the ore finding rate is increased, and cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of mineral exploration technology, and specifically provides a method for locating the hydrothermal center of porphyry deposits. Background Technology

[0002] Hydrothermal deposits are accumulations of useful minerals formed by the infilling and replacement of mineralized fluids in various favorable geological structures and rocks under specific physicochemical conditions. Hydrothermal deposits are the most complex and diverse type of mineral deposit, forming under different geological backgrounds through hydrothermal activity of varying compositions and origins. Delineating the mineralization center of hydrothermal deposits is of great significance in their exploration.

[0003] Traditional methods for delineating hydrothermal mineralization centers typically involve comprehensive studies such as large-scale alteration mapping and systematic sampling analysis. Epidote, due to its widespread distribution, is a characteristic mineral in phyllolithification alteration zones within porphyry systems. Existing techniques using epidote elements to determine hydrothermal centers often employ indicator elements such as Zn, Sr, B, V, La, and Y. However, these methods delineate a wide area with errors typically exceeding 200 meters, failing to accurately pinpoint the exact location of the hydrothermal center. While new ore bodies can be identified, the low precision makes it easy to miss main ore bodies or high-grade areas during drilling and sampling operations, significantly impacting resource assessment and increasing exploration costs. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for locating hydrothermal centers in porphyry deposits based on epidote indicator element variations. This method organically combines mineral geochemistry and mineral exploration prediction, solving the technical problems of low accuracy and long exploration cycles. The specific technical solution is as follows:

[0005] A method for locating the hydrothermal center of a porphyry deposit includes the following steps: S1, systematically collecting epidote-bearing rock samples in the target exploration area and recording the sampling location information of each sample; S2, performing compositional analysis on the epidote in the rock samples, including the content data of major elements Fe, Al and trace elements As, Sb, B, Mn, Pb and Sr; S3, matching and comparing the content data of each element obtained in step S2 with a predetermined epidote geochemical fingerprint model; the epidote geochemical fingerprint model characterizes the variation of the content of Fe, Al, As, Sb, B, Mn, Pb and Sr with the distance to the hydrothermal center, and the model is established based on sampling and inversion analysis of reference deposits with known hydrothermal centers; S4, determining the location of the hydrothermal center in the target exploration area based on the matching and comparison results of step S3.

[0006] This method revolutionizes the traditional approach of relying on single or a few indicators for rough inferences, transforming it into a precise positioning method driven by "big data" of known mineral deposits. By establishing and applying a specific geochemical fingerprint model for eight elements (Fe, Al, As, Sb, B, Mn, Pb, and Sr) in epidote, this scheme achieves quantitative and model-based identification of hydrothermal centers in porphyry deposits. This fundamentally overcomes the shortcomings of existing methods, such as large positioning errors (often exceeding 200 meters) and ambiguous indication ranges, significantly improving prediction accuracy to the specific distance scale represented by the model (e.g., 50-120 meters). This allows for direct and precise guidance of exploration project layout, greatly increasing the mineralization rate and reducing exploration costs, providing revolutionary and precise guidance for project layout.

[0007] Preferably, the epidote geochemical fingerprint model specifically includes the following elemental content ranges within a distance of 50-120 meters from the hydrothermal center: Fe content of 0.7-1 apfu, Al content of 2.1-2.3 apfu, As content of 10-40 ppm, Sb content of 1-20 ppm, B content of 6-35 ppm, Mn content of 1100-3100 ppm, Pb content of 50-90 ppm, and Sr content of 2300-2900 ppm.

[0008] This scheme provides the most sensitive and stable elemental content thresholds within a 50-120 meter range from the hydrothermal center, which have been discovered and repeatedly verified. By collecting and analyzing the Fe, Al, As, Sb, B, Mn, Pb, and Sr content in epidote samples, and applying the epidote geochemical fingerprint model, the predicted location of the hydrothermal center can be converged from the >200 meter error range of traditional methods to a more precise distance range characterized by the epidote geochemical fingerprint model. This yields the sampling location distribution within 50-120 meters of the hydrothermal center, enabling rapid and efficient delineation of the hydrothermal center within a smaller area, thus obtaining a more accurate target hydrothermal center location. This significantly improves the speed and accuracy of locating hydrothermal centers in porphyry deposits.

[0009] Preferably, in step S2, the component analysis includes analyzing major elements using electron probe microanalysis and analyzing trace elements using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS).

[0010] This approach ensures high precision and high spatial resolution of the original composition data. Through in-situ micro-area analysis, the true chemical composition of epidote can be accurately obtained, effectively avoiding interference from whole-rock analysis and guaranteeing the scientific validity and accuracy of the method from the data source.

[0011] To improve the accuracy of subsequent hydrothermal center delineation, it is necessary to remove epidote sample data of metamorphic origin. In order to accurately remove epidote samples of metamorphic origin, preferably, a data screening step is included before step S3: removing sample data in which the content of As and Sb elements in epidote samples is lower than their detection limits.

[0012] This approach automatically removes sample data that is not indicative or has an excessively low signal-to-noise ratio. This preprocessing step significantly improves the quality of the input model data, effectively filters background noise, and enhances the signal-to-noise ratio and robustness of the conclusions in subsequent comparisons.

[0013] Preferably, in step S3, the matching comparison is: determining whether the Fe and Al contents of a sample are both within the specified range, and whether the contents of at least four of the elements As, Sb, B, Mn, Pb, and Sr are within the specified range.

[0014] This scheme constructs an extremely rigorous discrimination logic through the synergistic constraints and cross-validation of multi-element indicators. This greatly reduces the probability of misjudgment caused by abnormal coupling of a single element, making the positioning conclusion more certain and resistant to interference.

[0015] Preferably, the epidote geochemical fingerprint model is expressed in the form of a box plot showing the variation of elemental content with distance.

[0016] This approach enables the model to scientifically express the statistical distribution characteristics of elemental content, rather than simply using thresholds. This makes the model more inclusive and explanatory of natural fluctuations in geological data, resulting in more robust patterns that better align with geological realities, thus enhancing the method's universality and scientific rigor.

[0017] Preferably, the element content distribution box plot includes collecting multiple sets of epidote samples at different distances from the hydrothermal center at the same intervals around the center of the rock-type deposit with a known hydrothermal center, analyzing the content data of each element in the collected epidote samples at different distances from the hydrothermal center, and then processing the content data to draw a box plot.

[0018] According to claim 7, a method for locating the hydrothermal center of a porphyry deposit is characterized in that the data processing includes calculating the upper quartile Qmax, lower quartile Qmin, interquartile range IQR, and outliers of each element content.

[0019] In this approach, the construction process of the box plot model is standardized and refined. By clarifying the statistical calculation process centered on quartiles, it ensures that the model can objectively and consistently depict the central tendency, dispersion, and data boundaries of element content. The step of identifying and eliminating outliers effectively filters outlier data points caused by analytical errors or local geological anomalies, thereby improving the purity and representativeness of the constructed geochemical fingerprint model.

[0020] The beneficial effects of this invention are:

[0021] This invention revolutionizes the traditional method of relying on a single or few indicators for rough inference by transforming it into a precise positioning method driven by "big data" of known mineral deposits. By establishing and applying a specific geochemical fingerprint model for eight elements (Fe, Al, As, Sb, B, Mn, Pb, and Sr) in epidote, it achieves quantitative and model-based identification of hydrothermal centers in porphyry deposits. This fundamentally overcomes the shortcomings of existing methods, such as large positioning errors and ambiguous indication ranges, significantly improving prediction accuracy to the specific distance scale represented by the model. Consequently, it can directly and accurately guide the layout of exploration projects, greatly increasing the mineralization rate and reducing exploration costs, providing revolutionary and precise guidance for project layout. Attached Figure Description

[0022] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a box plot of the principal elements of the present invention;

[0024] Figure 2 This is a box-shaped diagram of the trace elements of this invention. Detailed Implementation

[0025] The technical solution of the present invention will be clearly and completely described in conjunction with the accompanying drawings and through specific implementation methods of the embodiments of the present invention.

[0026] A method for locating the hydrothermal center of a porphyry mineral deposit includes the following steps:

[0027] S1. Systematically collect rock samples containing epidote in the target exploration area and record the sampling location information of each sample;

[0028] In this step, determining the target exploration area requires systematically collecting historical data of the study area, such as geological, geophysical, geochemical, and remote sensing data, comprehensively analyzing the mineralization potential, and delineating favorable mineralization zones. Within the delineated favorable zones, bedrock samples containing epidote are collected according to the geological zonation system, with a sampling density of >10 samples / square kilometer. The coordinates of each sampling point must be recorded using GPS or similar equipment, field photographs taken, and a detailed description of the lithology and alteration characteristics of the samples provided to support subsequent analysis and location of the hydrothermal center of porphyry deposits.

[0029] S2. Perform compositional analysis on the epidote in the rock sample to obtain the content data of Fe, Al, As, Sb, B, Mn, Pb and Sr elements;

[0030] In this step, samples from various locations were ground into probe slides and laser slides. First, the alteration characteristics of epidote were observed and recorded under a microscope. Then, the chemical composition of various altered epidotes was analyzed using electron probe microanalysis. Finally, typical epidote development areas were selected as micro-regions for in-situ elemental analysis using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to obtain elemental data and genetic types for each sample. The analyzed elements included Fe, Al, As, Sb, B, Mn, Pb, and Sr.

[0031] It should be noted that the origin of epidote is determined based on whether the content of As and Sb elements is above the detection limit. If the test value of either As or Sb is below the detection limit, the epidote is considered to be of metamorphic origin. Data of metamorphic epidote with content below the detection limit are discarded, while the micro-elemental data of hydrothermal epidote are retained for subsequent analysis. Data on As and Sb elements in epidote samples with content below their detection limits are discarded. The detection limit is preferably set to 0.01 ppm, which generally indicates that the in-situ elemental analyzer cannot detect the presence of As and Sb elements in the sample. This process eliminates sample data that are not indicative or have an excessively low signal-to-noise ratio.

[0032] S3. The content data of each element obtained in step S2 are matched and compared with a predetermined epidote geochemical fingerprint model. The epidote geochemical fingerprint model characterizes the variation of the content of Fe, Al, As, Sb, B, Mn, Pb and Sr elements with distance from the hydrothermal center. The model is established based on sampling and inversion analysis of reference deposits with known hydrothermal centers.

[0033] Specifically, the valid data obtained in step 2 are further filtered using Origin software. Only samples with Fe and Al contents within the corresponding epidote geochemical fingerprint model range, and at least four of the elements (As, Sb, B, Mn, Pb, and Sr) within the epidote geochemical fingerprint model range, are selected. These filtered samples are then plotted on a coordinate graph. Based on the predetermined epidote geochemical fingerprint model, and referring to… Figure 1 and Figure 2 The diagram shows the variation of elemental content with distance, specifically including: within a range of 50-120 meters from the hydrothermal center, the elemental content ranges as follows: Fe 0.7-1 apfu, Al 2.1-2.3 apfu, As 10-40 ppm, Sb 1-20 ppm, B 6-35 ppm, Mn 1100-3100 ppm, Pb 50-90 ppm, and Sr 2300-2900 ppm; and epidote 400-470 meters from the hydrothermal center, with Fe 0.8-1.2 apfu, Al 1.9-2.2 apfu, As 5-15 ppm, Sb 0-3 ppm, B 10-90 ppm, Mn 600-1300 ppm, Pb 1-3 ppm, and Sr 300-900 ppm.

[0034] In other words, apart from As and Sb, which are used to determine the origin of epidote, the higher the content of the other indicator elements Al, Mn, Pb, and Sr, the closer the corresponding sample is to the hydrothermal center; the lower the content of the indicator element Fe, the closer the corresponding sample is to the hydrothermal center.

[0035] S4. Based on the matching and comparison results of step S3, determine the location of the hydrothermal center in the target exploration area.

[0036] Specifically, using each qualified sample as the delineation center, the corresponding radius is used as the delineation radius on the coordinate graph to delineate the predicted mineralization center, and the area with the most intersection points is selected as the hydrothermal center of the target porphyry deposit.

[0037] The above-mentioned epidote geochemical fingerprint model was obtained in the following manner:

[0038] Epidote samples were selected from a specific hydrothermal center. Samples were collected from different platforms around the hydrothermal center at approximately 100m intervals. The distance from the sample to the hydrothermal center was determined by the horizontal distance between the sample and the hydrothermal center, as well as the elevation difference between the hydrothermal center and the samples from different platforms. The samples were divided into six groups based on their distance from the hydrothermal center (50-120m, 120-190m, 190-260m, 260-330m, 330-400m, 400-470m). Based on observation under an indoor microscope, electron probe microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) were used to analyze the epidote in the deposit. The data are shown in Tables 1 and 2.

[0039]

[0040]

[0041] Continued from Table 1

[0042]

[0043]

[0044]

[0045] Table 1: Electron probe microanalysis results of major elements in epidote (ω(B) / %)

[0046]

[0047]

[0048]

[0049] Table 2. LA-ICP-MS Analysis Results of Trace Elements in Epidote (w(B) / 10) -6 )

[0050] In Table 1, FeO represents FeO T Based on the data in the two tables above, elements with low content and irregular changes are removed, and only those elements are retained. Data processing is then performed on these data to calculate the upper quartile Qmax, lower quartile Qmin, interquartile range IQR, and outliers for each element.

[0051] Specifically, Qmax = Q1 - 1.5 × IQR, Qmin = Q3 + 1.5 × IQR, where Q1 is the first quartile of an element in the sample group, i.e., the 25th percentile of the data in sequential order; Q3 is the third quartile of the element in the sample group, i.e., the 75th percentile of the data in sequential order; and IQR = Q3 - Q1.

[0052] Outliers exceeding the upper quartile Qmax and lower quartile Qmin in the calculated data are marked and excluded when plotting the box plot. Based on this, a box plot reflecting the normal fluctuation range of element content is generated, resulting in the following... Figure 1 and Figure 2 ( Figure 1 Legend and Figure 2 (Similar to the previous conclusions), the following conclusions were drawn: Epidote located 50-120m from the hydrothermal center has the following contents: Fe content 0.7-1apfu, Al content 2.1-2.3apfu, As content 10-40ppm, Sb content 1-20ppm, B content 6-35ppm, Mn content 1100-3100ppm, Pb content 50-90ppm, and Sr content 2300-2900ppm;

[0053] Epidote located 400–470 m from the hydrothermal center has the following contents: Fe 0.8–1.2 ppm, Al 1.9–2.2 ppm, As 5–15 ppm, Sb 0–3 ppm, B 10–90 ppm, Mn 600–1300 ppm, Pb 1–3 ppm, and Sr 300–900 ppm.

[0054] Experimental Example 1:

[0055] Taking a mining area in a certain region as an example:

[0056] S1: The system collects historical data of the study area, such as geological, geophysical, geochemical, and remote sensing data, and comprehensively analyzes the mineralization potential to delineate favorable mineralization zones. Within the delineated favorable zones, chlorite-bearing bedrock samples are collected according to the geological zoning system. Sample number, sampling coordinates, lithology type, and alteration type are recorded. Details are shown in the table below:

[0057]

[0058] S2: The samples were ground into probe slides and laser slides. First, the alteration characteristics of chlorite were observed and recorded under a microscope; then, the chemical composition of Fe and Al compounds in various altered chlorite was analyzed by electron probe microanalysis; finally, typical chlorite development areas were selected as micro-regions for in-situ elemental analysis by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to obtain the contents of major elements Fe and Al, as well as trace elements As, Sb, B, Mn, Pb, and Sr, and the genetic type of the samples.

[0059] S3: Import the data obtained in step S2 into Origin software, use the software to automatically remove sample data with As or Sb content below the detection limit, and analyze whether the content of each element in each sample conforms to the epidote geochemical fingerprint model and is within the corresponding radius range.

[0060] S4: Finally, using each qualified sample as the delineation center, the corresponding radius is used as the delineation radius on the coordinate graph to delineate the predicted mineralization center, and the area with the most intersection points is selected as the target porphyry deposit hydrothermal center.

[0061] Drilling has verified that the above process has achieved accurate mineral exploration results.

[0062] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of protection claimed by the present invention.

Claims

1. A method for locating the hydrothermal center of a porphyry mineral deposit, characterized in that, Includes the following steps: S1. Systematically collect rock samples containing epidote in the target exploration area and record the sampling location information of each sample; S2. Perform compositional analysis on the epidote in the rock sample to obtain the content data of major elements Fe, Al and trace elements As, Sb, B, Mn, Pb and Sr. S3. The content data of each element obtained in step S2 are matched and compared with a predetermined epidote geochemical fingerprint model. The epidote geochemical fingerprint model characterizes the variation of the content of Fe, Al, As, Sb, B, Mn, Pb and Sr elements with distance from the hydrothermal center. The model is established based on sampling and inversion analysis of reference deposits with known hydrothermal centers. S4. Based on the matching and comparison results of step S3, determine the location of the hydrothermal center in the target exploration area.

2. The method for locating the hydrothermal center of a porphyry deposit according to claim 1, characterized in that, The geochemical fingerprint model of epidote specifically includes the following elemental content ranges within a distance of 50-120 meters from the hydrothermal center: Fe content of 0.7-1 apfu, Al content of 2.1-2.3 apfu, As content of 10-40 ppm, Sb content of 1-20 ppm, B content of 6-35 ppm, Mn content of 1100-3100 ppm, Pb content of 50-90 ppm, and Sr content of 2300-2900 ppm.

3. A method for locating the hydrothermal center of a porphyry deposit according to claim 1 or 2, characterized in that, In step S2, the component analysis includes analyzing major elements using electron probe microanalysis and analyzing trace elements using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS).

4. The method for locating the hydrothermal center of a porphyry deposit according to claim 1, characterized in that, Before step S3, a data screening step is also included: removing sample data where the content of As and Sb elements in epidote samples is lower than their detection limits.

5. The method for locating the hydrothermal center of a porphyry deposit according to claim 2, characterized in that, In step S3, the matching comparison is: determining whether the Fe and Al contents of a sample are both within the specified range, and whether the contents of at least four of the elements As, Sb, B, Mn, Pb, and Sr are within the specified range.

6. The method for locating the hydrothermal center of a porphyry deposit according to claim 2, characterized in that, The geochemical fingerprint model of epidote is expressed in the form of a box plot showing the variation of elemental content with distance.

7. The method for locating the hydrothermal center of a porphyry deposit according to claim 6, characterized in that, The element content distribution box plot includes collecting multiple sets of epidote samples at different distances from the hydrothermal center, distributed at the same intervals between the centers of rock-type deposits around the known hydrothermal center. The content data of each element in the collected epidote samples at different distances from the hydrothermal center are analyzed, and the content data are then processed and plotted into a box plot.

8. The method for locating the hydrothermal center of a porphyry deposit according to claim 7, characterized in that, The data processing procedure includes calculating the upper quartile Qmax, lower quartile Qmin, interquartile range IQR, and outliers for each element.

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