A method for quickly delineating porphyry deposit ore bodies using trace element content of chlorite

Abstract

The present invention discloses a method for quickly delineating porphyry deposit ore bodies using chlorite trace element content, and relates to the technical field of ore deposit exploration. The method includes performing multiple three-dimensional spatial sampling from a known porphyry deposit mining area to obtain multiple samples; grinding multiple samples into thin slices, screening thin slices containing chlorite; performing scanning electron microscope analysis to screen out samples to be tested; performing electron probe analysis to obtain the content of major elements; performing LA‑ICP‑MS analysis to obtain the content of trace elements; screening target data; and constructing a porphyry deposit chlorite exploration marker equation based on the relationship between the trace elements in the target data and the spatial information of the corresponding samples. The present application greatly improves the amplitude and range of element anomalies, improves the efficiency and accuracy of porphyry deposit prospecting, effectively proposes forward-looking predictions for prospecting in the deep edge of the deposit, reduces exploration costs and time, and efficiently and reasonably utilizes mineral resources.

Description

Technical Field

[0001] The invention relates to the technical field of mineral deposit exploration, and in particular to a method for rapidly delineating a porphyry mineral deposit ore body by utilizing the trace element content of chlorite. Background Art

[0002] With the continuous development of the world economy, the mineral resources on the surface are becoming increasingly depleted, and the depth of mineral exploration is getting deeper and deeper. However, for deposits in covered areas, especially deep concealed deposits, traditional geochemical exploration methods have limited effects, and geophysical exploration methods often have multiple solutions, which makes the current prospecting and exploration work face huge challenges. Therefore, there is an urgent need for more effective methods to improve the accuracy of concealed ore body exploration, so as to establish efficient mineral exploration signs. Altered minerals are the key objects and important means for studying the genesis of hydrothermal deposits and guiding prospecting and exploration. Systematically sorting out the types, combinations, spatial distribution characteristics and physical and chemical typological characteristics of altered minerals in mining areas will help understand the genetic mechanism of ore deposits and improve the efficiency of prospecting and exploration. Porphyry deposits are easy to open-pit mining, low grade, huge scale and uniform mineralization. They have very important economic value and provide nearly 75% of the world's copper, 50% of molybdenum and 20% of gold, as well as a small amount of other metals such as silver, zinc, lead, bismuth, etc., which is the most important type of copper ore in the world. In the periphery of the porphyry deposits, chlorite is widely developed, usually coexisting with epidote, calcite, quartz and other minerals, and is closely related to the mineralization process.

[0003] As an important hydrothermal alteration mineral, chlorite is an important carrier for recording the hydrothermal process of ore deposits and is of great significance for indicating the genesis of ore deposits. Therefore, the research on its chemical composition and structural characteristics has always been valued by experts and scholars at home and abroad. However, previous studies on chlorite mainly focused on its chemical composition and structural characteristics, and did not use chlorite characteristics, especially trace elements, as a mineral exploration method to determine the mineralization center of porphyry deposits. In addition, chlorite often contains other mineral inclusions and forms a complex symbiotic relationship with other minerals, which interferes with the work of mineral exploration using chlorite components.

[0004] In the prior art, Raman spectroscopy and electron probe data are used to study chlorite to identify the hydrothermal center of porphyry deposits. However, the chlorite elements are only the major element data of chlorite. However, the major element data of chlorite generally has a small variation range and is easily affected by the composition of the surrounding rock. The most important thing is that this method is mainly a qualitative description rather than a quantitative description for identifying the hydrothermal center of porphyry deposits. In addition, the data of chlorite often contains other mineral inclusions, which affect the chlorite data and also affect the accuracy of using chlorite data as an exploration method.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The object of the present invention is to provide a method for rapidly delineating porphyry deposit ore bodies by using the trace element content of chlorite, which can realize quantitative research and has high exploration accuracy.

[0007] The present invention is achieved in that:

[0008] In a first aspect, the present invention provides a method for rapidly delineating a porphyry deposit ore body by using the trace element content of chlorite, comprising:

[0009] (1) performing multiple three-dimensional spatial sampling within a preset radius from the center of the ore body of a known porphyry deposit to obtain multiple samples, and recording the spatial information of each sample;

[0010] (2) grinding each of the samples into thin slices, observing the thin slices under a microscope, and screening the thin slices containing chlorite;

[0011] (3) performing scanning electron microscopy analysis on the chlorite-containing slices, and selecting the slices with uniform chlorite structure and no impurities as samples to be tested;

[0012] (4) performing electron probe analysis on the sample to be tested to obtain and record the content of major elements in the chlorite in the sample to be tested;

[0013] (5) performing LA-ICP-MS analysis on the sample to be tested to obtain and record the trace element content of chlorite in the sample to be tested;

[0014] (6) screening the content of the major elements and the content of the trace elements of each of the samples to be tested to exclude samples to be tested containing other minerals, and taking the remaining qualified sample data to be tested as target data;

[0015] (7) Based on the relationship between the trace elements in the target data and the spatial information of the corresponding sample, the distance of the sample from the center of the ore body is used as the horizontal coordinate, and the trace element index of chlorite in the sample is used as the vertical coordinate to construct the porphyry deposit chlorite exploration indicator equation y=Ae Bx , wherein the calculation formula for the distance of the sample from the center of the ore body is x=B*ln(y / A), wherein y represents the trace element index in chlorite, and A and B are constants determined according to the equation.

[0016] In an optional embodiment, screening to exclude samples containing other minerals includes: screening the same sample to be tested, and selecting samples having a sum of Na2O, K2O and CaO contents less than 0.5wt.%, Si element content between 100000-225000ppm, K element content less than or equal to 1000ppm, Ti element content less than or equal to 1000ppm and Zr element content less than or equal to 2ppm as qualified sample data to be tested.

[0017] In an optional embodiment, the trace element index includes the content of a single trace element or the ratio of the contents of two trace elements.

[0018] In an optional embodiment, the trace element index is the ratio of the contents of two trace elements, and the determination method is: correspond the trace elements in the target data and the spatial information of the corresponding samples, screen out a first element group whose content decreases as the chlorite moves away from the center of the ore body and a second element group whose content increases, screen out the element with the largest change in the first element group as the first target element, screen out the element with the largest change in the second element group as the second target element, and the trace element index is the ratio of the first target element to the second target element.

[0019] In an optional embodiment, the first target element is Ti, and the second target element is Sr.

[0020] In an optional embodiment, the major element includes an element whose content in chlorite is greater than or equal to 0.1%, and the trace element includes an element whose content in chlorite is less than 0.1%.

[0021] In an optional embodiment, the major element includes at least one of Fe, Mg, Si and Al.

[0022] In an optional embodiment, the trace element includes at least one of Na, K, Ti, Sr, Sc, V, Ni, Ga, Ca, Li, Mn and Zn.

[0023] In an optional embodiment, the spatial information of the sample includes at least one of the distance of the sample from the center of the ore body, the longitude of the sample, and the latitude of the sample.

[0024] In an optional embodiment, the thickness of the sheet is 20-40 μm.

[0025] In an optional implementation, the preset radius is 1000-4000m.

[0026] The present invention has the following beneficial effects: the method for quickly delineating the ore body of a porphyry deposit using the trace element content of chlorite provided by the present application selects trace elements as a mark for judging the location of the ore body, and the content thereof varies by two or three orders of magnitude, and is less affected by the composition of the surrounding rock, which can expand the amplitude and range of the index change, and the present application also proposes a process for how to perform chlorite data selection, thereby improving the efficiency and accuracy of porphyry deposit prospecting, and at the same time solving the difficult and inefficient prospecting problems in the deep and edge areas around the mining area. In addition, the method for quickly delineating the ore body of a porphyry deposit using the trace element content of chlorite provided by the present application is a quantitative method, and an equation for the trace element of chlorite and the distance between chlorite and the ore body is also provided, so that the distance between chlorite and the ore body can be quantitatively known using the chlorite composition, rather than qualitatively. Therefore, the method provided by the present application for quickly delineating the ore body of a porphyry deposit using the trace element content of chlorite is a method for accurately and quantitatively finding the location of the hydrothermal center, i.e., the ore body, of a porphyry deposit. The location of the mineralization center is determined by the relationship between the trace elements of chlorite and the distance from the chlorite to the ore body, thereby delineating the target area for prospecting. Compared with previous mineral exploration methods, the present invention uses the trace element content of chlorite as a sign to judge the location of the ore body, greatly improving the amplitude and range of element anomalies, and improving the efficiency and accuracy of prospecting for porphyry deposits. The present invention can effectively remove chlorite containing mineral inclusions and forming a complex symbiotic relationship with other minerals by screening the data, thereby improving the accuracy of delineating the ore body using trace elements of chlorite. The present invention can effectively avoid the leakage of copper ore bodies in porphyry deposits by accurately determining the location of the mineralization center, effectively make forward-looking predictions for prospecting in the deep edge of the ore deposit, reduce exploration costs and time, and efficiently and reasonably utilize mineral resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 The distribution diagram of trace elements of chlorite provided in Example 1 of the present application as the distance of the chlorite from the ore body changes. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0030] The present invention provides a method for quickly delineating a porphyry deposit ore body by using the trace element content of chlorite, which comprises the following steps:

[0031] (1) Sampling.

[0032] Multiple three-dimensional spatial sampling is performed multiple times within a preset radius (e.g., 1000-4000m) from the center of the ore body of a known porphyry deposit to obtain multiple samples, and the spatial information of each sample is recorded. The spatial information of the sample includes at least one of the distance of the sample from the center of the ore body, the longitude of the sample, and the latitude of the sample.

[0033] (2) Select samples.

[0034] Multiple samples were polished into thin slices with a thickness of 20-40 μm, and the slices were observed under a microscope to screen the slices containing chlorite and exclude the slices without chlorite.

[0035] (3) Scanning electron microscopy analysis.

[0036] The thin sections containing chlorite were analyzed by scanning electron microscope, and the thin sections with uniform chlorite structure and without other mineral inclusions were selected as the samples to be tested.

[0037] (4) Electron probe analysis

[0038] The electron probe can perform qualitative or quantitative analysis on the chemical composition of a tiny area (micrometer level) in a sample. In the present application, the electron probe analysis is performed on the sample to be tested to obtain and record the content of major elements in the chlorite in the sample to be tested; the major elements include elements whose content in chlorite is greater than or equal to 0.1%, and the major elements include at least one of Fe, Mg, Si and Al.

[0039] (5) LA-ICP-MS analysis.

[0040] LA-ICP-MS refers to laser ablation inductively coupled plasma mass spectrometry. The analysis accuracy of LA-ICP-MS is higher than that of electron probe. In this application, LA-ICP-MS analysis is performed on the sample to be tested to obtain and record the trace element content of chlorite in the sample to be tested; trace elements include elements with a content of less than 0.1% in chlorite. Trace elements include at least one of Na, K, Ti, Sr, Sc, V, Ni, Ga, Ca, Li, Mn and Zn.

[0041] (6)Data screening.

[0042] The major element content and trace element content of each sample to be tested are screened to exclude samples containing other minerals, and the remaining qualified sample data are used as target data.

[0043] Screening to exclude samples containing other minerals includes: screening the same sample to be tested, selecting samples with a sum of Na2O, K2O and CaO contents less than 0.5wt.%, Si element content between 100000-225000ppm, K element content less than or equal to 1000ppm, Ti element content less than or equal to 1000ppm and Zr element content less than or equal to 2ppm as qualified sample data to be tested.

[0044] Among them, excessively high contents of Na2O, K2O and CaO indicate that chlorite may contain other mineral inclusions, or that chlorite may form a complex symbiotic relationship with other minerals. Such a situation will interfere with the use of chlorite components for mineral exploration, so it is necessary to exclude it. When the contents of Si, K, Ti and Zr exceed the range specified in this application, it means that chlorite may be a mixture. Therefore, in this application, by screening all the detected data and eliminating them when they do not meet the above standards, the reliability of the data in this application can be guaranteed, thereby improving the accuracy of the detection method.

[0045] (7) Construct the equation.

[0046] According to the relationship between the trace elements in the target data and the spatial information of the corresponding samples, the distance between the sample and the center of the ore body is taken as the horizontal coordinate, and the trace element index of chlorite in the sample is taken as the vertical coordinate to construct the chlorite exploration indicator equation y=Ae Bx , where the distance between the sample and the center of the ore body is calculated as x=B*ln(y / A), where y represents the trace element index in chlorite, and A and B are constants determined according to the equation.

[0047] In the present application, the trace element index includes the content of a single trace element or the ratio of the contents of two trace elements.

[0048] Preferably, the trace element index is the ratio of the content of two trace elements, and the determination method is: correspond the spatial information of the trace elements in the target data and the corresponding samples, screen out the first element group whose content decreases as the chlorite moves away from the center of the ore body and the second element group whose content increases, screen out the element with the largest change in the first element group as the first target element, screen out the element with the largest change in the second element group as the second target element, and the trace element index is the ratio of the first target element to the second target element. More preferably, the first target element is Ti and the second target element is Sr.

[0049] Since the major element data of chlorite generally has a small range of variation and is easily affected by the composition of the surrounding rock; generally, the content of trace elements in chlorite varies by two or three orders of magnitude, while the major elements vary by only one order of magnitude at most, therefore, in this application, trace elements are selected as a sign to judge the location of the ore body, especially the ratio of the first target element to the second target element as a trace element indicator, which can expand the amplitude and range of the indicator change, and this application also proposes a process for how to select chlorite data, thereby improving the efficiency and accuracy of porphyry deposit prospecting, and at the same time solving the problem of difficulty and low efficiency in prospecting in the deep and edge parts around the mining area. In addition, the method provided by this application for quickly delineating the ore body of porphyry deposits using the content of trace elements in chlorite is a quantitative method, and an equation for the distance between chlorite trace elements and chlorite and the ore body is also given, so that the distance between chlorite and the ore body can be quantitatively known using the chlorite composition, rather than qualitatively.

[0050] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0051] Example 1

[0052] In these two examples, the three-dimensional spatial information of the samples was recorded in detail through surface sampling in the mining area. The samples collected in the field were selected and ground into thin slices, and then observed under a microscope to find the thin slices containing chlorite; the thin slices containing chlorite were subjected to scanning electron microscope analysis, and the chlorite structure was studied. The thin slices with uniform chlorite structure and no impurities were selected as the samples to be tested, and the thin slices with uneven composition or obvious impurities were removed. Based on the structural research, the chlorite was subjected to electron probe analysis to obtain and record the major element composition of the chlorite; based on the electron probe analysis, the chlorite was subjected to LA-ICP-MS analysis to obtain and record its trace element content; the chlorite data was screened, and the selection criteria were that the sum of the Na2O, K2O and CaO contents of the chlorite was less than 0.5wt.%, the Si content was between 100000–225000ppm, the K content was less than or equal to 1000ppm, the Ti content was less than or equal to 1000ppm, and the Zr content was less than or equal to 2ppm. According to the relationship between the trace elements in the target data and the spatial information of the corresponding samples, the distance between the sample and the center of the ore body is taken as the horizontal coordinate, and the trace element index of chlorite in the sample is taken as the vertical coordinate to construct the chlorite exploration indicator equation y=Ae Bx .

[0053] See also Figure 1 As found in this application, within 3.2 kilometers from the ore body, as the chlorite moves away from the ore body, its Ti / Sr ratio gradually decreases, and the equation is obtained: x=B*ln(y / A), where X represents the distance of the chlorite from the ore body, y represents the chlorite Ti / Sr ratio, and A and B are 600 and -0.0024 respectively. According to the equation provided by this application, the actual distance of the chlorite from the ore body can be known, which provides a forward-looking prediction for subsequent prospecting in the deep side of the ore deposit, reduces exploration costs and time, and makes efficient and reasonable use of mineral resources.

[0054] In summary, the method for quickly delineating the ore body of a porphyry deposit using the trace element content of chlorite provided by the present application selects trace elements as a marker for determining the location of the ore body, and the content thereof varies by two or three orders of magnitude, and is less affected by the composition of the surrounding rock, especially the ratio of the first target element to the second target element is used as a trace element indicator, which can expand the amplitude and range of the indicator change, and the present application also proposes a process for how to perform chlorite data selection, thereby improving the efficiency and accuracy of porphyry deposit prospecting, and at the same time solving the problem of difficulty and low efficiency in prospecting in the deep and edge areas around the mining area. In addition, the method for quickly delineating the ore body of a porphyry deposit using the trace element content of chlorite provided by the present application is a quantitative method, and an equation for the chlorite trace element and the distance of chlorite from the ore body is also provided, so that the distance of chlorite from the ore body can be quantitatively known using the chlorite composition, rather than qualitatively. Therefore, the method provided by the present application for quickly delineating the ore body of a porphyry deposit using the trace element content of chlorite is a method for accurately and quantitatively finding the location of the hydrothermal center, i.e., the ore body, of a porphyry deposit. The location of the mineralization center is determined by the relationship between the trace elements of chlorite and the distance from the chlorite to the ore body, thereby delineating the target area for prospecting. Compared with previous mineral exploration methods, the present invention uses the trace element content of chlorite as a sign to judge the location of the ore body, greatly improving the amplitude and range of element anomalies, and improving the efficiency and accuracy of prospecting for porphyry deposits. The present invention can effectively remove chlorite containing mineral inclusions and forming a complex symbiotic relationship with other minerals by screening the data, thereby improving the accuracy of delineating the ore body using trace elements of chlorite. The present invention can effectively avoid the leakage of copper ore bodies in porphyry deposits by accurately determining the location of the mineralization center, effectively make forward-looking predictions for prospecting in the deep edge of the ore deposit, reduce exploration costs and time, and efficiently and reasonably utilize mineral resources.

[0055] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for rapidly delineating porphyry deposit ore bodies using trace element content of chlorite, characterized in that: It includes: (1) performing multiple three-dimensional spatial sampling within a preset radius from the center of the ore body of a known porphyry deposit to obtain multiple samples, and recording the spatial information of each sample; (2) grinding each of the samples into thin slices, observing the thin slices under a microscope, and selecting the thin slices containing chlorite; (3) performing scanning electron microscopy analysis on the thin slices containing chlorite, and selecting thin slices with uniform chlorite structure and composition and without other mineral inclusions as samples to be tested; (4) performing electron probe analysis on the sample to be tested to obtain and record the content of major elements in the chlorite in the sample to be tested; (5) performing LA-ICP-MS analysis on the sample to be tested to obtain and record the trace element content of chlorite in the sample to be tested; (6) screening the major element content and the trace element content of each of the samples to be tested to exclude samples to be tested containing other mineral inclusions, and taking the remaining qualified sample data to be tested as target data, and screening to exclude samples to be tested containing other minerals includes: screening the same sample to be tested, and selecting the samples to be tested with a sum of Na2O, K2O and CaO contents less than 0.5wt%, Si content between 100000-225000 ppm, K content less than or equal to 1000 ppm, Ti content less than or equal to 1000 ppm and Zr content less than or equal to 2 ppm as qualified sample data to be tested; (7) Based on the relationship between the trace elements in the target data and the spatial information of the corresponding sample, the distance of the sample from the center of the ore body is used as the horizontal coordinate, and the trace element index of chlorite in the sample is used as the vertical coordinate to construct the porphyry deposit chlorite exploration indicator equation y=Ae Bx , wherein the calculation formula of the distance of the sample from the center of the ore body is x=B*ln(y / A), wherein y represents the trace element index in chlorite, A and B are constants determined according to the equation, and the trace element index includes the content of a single trace element or the ratio of the contents of two trace elements; the trace element index is the ratio of the contents of two trace elements, and its determination method is: correspond the spatial information of the trace elements in the target data and the corresponding samples, screen out the first element group whose content decreases as the chlorite moves away from the center of the ore body and the second element group whose content increases, screen out the element with the largest change in the first element group as the first target element, screen out the element with the largest change in the second element group as the second target element, and the trace element index is the ratio of the first target element to the second target element.

2. The method for rapidly delineating porphyry deposit ore bodies by using the trace element content of chlorite according to claim 1, characterized in that: The first target element is Ti, and the second target element is Sr.

3. The method for rapidly delineating porphyry deposit ore bodies by using the trace element content of chlorite according to claim 1, characterized in that: The major elements include elements whose content in chlorite is greater than or equal to 0.1%, and the trace elements include elements whose content in chlorite is less than 0.1%.

4. The method for rapidly delineating porphyry deposit ore bodies by using the trace element content of chlorite according to claim 3, characterized in that: The major element includes at least one of Fe, Mg, Si and Al, and the trace element includes at least one of Na, K, Ti, Sr, Sc, V, Ni, Ga, Ca, Li, Mn and Zn.

5. The method for rapidly delineating porphyry deposit ore bodies by using the trace element content of chlorite according to any one of claims 1 to 4, characterized in that: The spatial information of the sample includes at least one of the distance of the sample from the center of the ore body, the longitude of the sample, and the latitude of the sample.

6. The method for rapidly delineating porphyry deposit ore bodies by using trace element content of chlorite according to any one of claims 1 to 4, characterized in that: The thickness of the sheet is 20-40 μm.

7. The method for rapidly delineating porphyry deposit ore bodies by using the trace element content of chlorite according to any one of claims 1 to 4, characterized in that: The preset radius is 1000-4000m.

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