Method for judging migration path of ore-forming hydrothermal solution by using rutile

Abstract

The invention provides a method for judging a migration path of a metallogenic hydrothermal solution by using rutile, and relates to the field of exploration geology, and the method comprises the following steps: collecting a metallogenic porphyry sample of a research area, and obtaining sampling point data of each sampling point; treating the ore-forming porphyry samples, and determining the characteristic data of rutile in each ore-forming porphyry sample; calculating the mineralization temperature value of each mineralization porphyry sample according to the zirconium content of rutile; testing the average titanium isotope value of each ore-forming porphyry sample; and according to the longitude and latitude data, the temperature value and the titanium isotope value of the sampling point, determining the migration path of the ore-forming hydrothermal solution. The temperature value and the titanium isotope value are determined according to the zirconium content of rutile, the migration path of the ore-forming hydrothermal solution is determined, and the migration path of the ore-forming hydrothermal solution of all porphyry copper ore can be accurately predicted.

Description

Technical Field

[0001] The present application relates to the field of exploration geology, and in particular to a method for determining the migration path of mineralization hydrothermal fluids using rutile. Background Art

[0002] Porphyry deposits are characterized by large scale, shallow ore bodies and easy mining. They account for about 70% of the world's copper production, more than 95% of the world's molybdenum production, and more than 20% of the world's gold. Therefore, they are one of the types of deposits that the industry focuses on. This type of deposit is mainly enriched by hydrothermal fluids exsoluted from magma. Revealing the migration direction of ore-forming fluids and the changes in fluid composition and mineral combinations during the migration process is an effective method to lock metal precipitation. Locking the migration path of ore-forming hydrothermal fluids can quickly lock the scope and location of the ore body.

[0003] In the early stage of porphyry mineralization system, the exsolution fluid generally has high temperature and high oxygen fugacity characteristics, which is conducive to the migration of metals. However, in the metal precipitation stage, the temperature and oxygen fugacity of the fluid will decrease, and the decrease in oxygen fugacity is related to the presence of a large amount of magnetite crystals during the cooling process. Therefore, the definition of the migration path of the hydrothermal fluid in porphyry deposits needs to be combined with the changes in fluid temperature and oxygen fugacity.

[0004] Fluid inclusions are an effective method to limit fluid temperature changes, but this method is difficult to limit the oxygen fugacity of the fluid. Currently, the limitation of fluid oxygen fugacity is usually roughly limited in combination with mineral paragenesis, which is less accurate.

[0005] The main geological methods include geological mapping to identify alteration zoning and mineral paragenesis relationships to determine hydrothermal migration and replacement paths; mineralogical methods use the spatial changes in the mineral geochemistry of altered minerals to determine hydrothermal migration and replacement paths; and the changes in short-wave infrared spectra such as wavelength and absorption peak characteristics of mica, kaolinite and some other clay minerals caused by spatial temperature changes can also be used to identify hydrothermal migration and replacement paths.

[0006] Geological methods such as geological mapping are time-consuming, require a lot of manpower and material resources, are expensive, require technicians to have high professional knowledge, and it is difficult to quantitatively determine the hydrothermal migration and replacement paths; while the mineralogical and spectral methods mainly use the changes in mineral chemistry and spectral characteristics such as wavelength and absorption peaks caused by changes in temperature in space of altered minerals such as chlorite and epidote. This method has certain application prospects in hydrothermal migration and replacement paths, but it is not suitable for all porphyry copper deposits, because most porphyry copper deposits rarely develop alteration minerals such as chlorite and epidote in the potash zone near the hydrothermal center. At the same time, due to the superposition of hydrothermal fluids in different hydrothermal centers in multi-thermal center deposits, the mineral chemistry and spectral characteristics of altered minerals lose their regularity in space, and the hydrothermal migration and replacement paths cannot be accurately judged. Therefore, there is currently a lack of reliable methods for determining the hydrothermal migration and replacement paths of porphyry copper deposits. Summary of the invention

[0007] The purpose of the present invention is to solve the problems mentioned in the above background technology and to provide a method for accurately determining the migration path of mineralization hydrothermal fluids in porphyry deposits based on rutile.

[0008] A method for determining the migration path of ore-forming hydrothermal fluids using rutile, the method comprising the following steps:

[0009] S1: Collect mineralized porphyry samples in the study area, pre-process each sample, and mark the location of rutile in each sample;

[0010] S2: For each sample, the zirconium content in each rutile is measured to obtain the average zirconium content of the sample, and the mineralization temperature of the sample is calculated based on the average zirconium content;

[0011] S3: Get the average titanium isotope value of the sample;

[0012] S4: Determine the migration path of the ore-forming hydrothermal fluid based on the longitude and latitude data, mineralization temperature and average titanium isotope value of each sample.

[0013] Furthermore, step S1 specifically includes: sampling in space according to the exploration grid, collecting mineralized porphyry samples, and recording the collection longitude and latitude coordinate data of each sample sampling point;

[0014] The collected samples were ground into laser sheets, and the output status, size and position of rutile in each sample were observed and recorded.

[0015] Furthermore, step S2 is specifically as follows:

[0016] In-situ micro-area element analysis is performed on the rutile in each sample to determine whether the Zr content in the rutile is uniform, to exclude the presence of Zr-rich inclusions in the rutile, and finally to retain the rutile without inclusions and measure the zirconium content in the rutile; for samples containing multiple rutiles, the zirconium content values ​​measured in each rutile are averaged to obtain the average zirconium content of the sample; combined with the average zirconium content of the sample, the mineralization temperature of the sample is calculated.

[0017] Furthermore, the formula for calculating the sample mineralization temperature T is as follows:

[0018]

[0019] Furthermore, step S3 is specifically as follows:

[0020] The in-situ titanium isotope of each rutile in the test sample is measured; for a sample containing multiple rutiles, the in-situ titanium isotope value of each rutile measured is averaged to obtain the average titanium isotope value of the sample.

[0021] Further, step S4 is specifically as follows:

[0022] Analyze whether the mineralization temperature of each sample changes in space. If there is no change, it means that there is no hydrothermal migration channel in the study area; if there is, then:

[0023] Linear fitting is performed on the mineralization temperature and average titanium isotope value of multiple samples. If the mineralization temperature and average titanium isotope value of the samples are negatively correlated, it means that the study area has mineralization potential. The evolution direction of the mineralization temperature values ​​of multiple samples from high temperature to low temperature is the direction of the migration path of the mineralization hydrothermal fluid.

[0024] If the mineralization temperature and average titanium isotope value of the samples are uncorrelated or positively correlated, it indicates that the study area has no mineralization potential and no hydrothermal migration pathway exists.

[0025] The beneficial effects brought by the technical solution provided by the present invention are:

[0026] The spatial temperature distribution is calculated by measuring the zirconium content in rutile in ore-forming porphyry samples, and the presence of a process of oxygen fugacity reduction in the ore-forming fluid is determined by testing the titanium isotope value in rutile. The migration path of the ore-forming hydrothermal fluids in the porphyry deposits is then determined, solving the complexity and inefficiency problems of geological and geochemical methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present application will be further described below with reference to the accompanying drawings and embodiments, in which:

[0028] Figure 1It is a correlation diagram between temperature and titanium isotope in rutile of the method for judging the migration path of ore-forming hydrothermal fluids in porphyry deposits based on rutile in Example 1 of the present invention. DETAILED DESCRIPTION

[0029] In order to have a clearer understanding of the technical features, purposes and effects of the present application, the specific implementation methods of the present application are now described in detail with reference to the accompanying drawings.

[0030] Rutile minerals are extremely stable, with low element diffusion rates. At the same time, their trace elements are mainly controlled by the trace element content and distribution coefficient in the melt, thus providing the possibility of using rutile to identify the hydrothermal migration and replacement pathways of porphyry deposits. Rutile is the most widely distributed accessory mineral in porphyry deposits. It is widely developed in the potash zone, sericite zone, mud zone and chlorite zone of porphyry copper deposits. The formation of rutile is mainly through the alteration of titanium-rich minerals such as biotite and titanite during the interaction between ore-forming fluids and rocks, and finally forms hydrothermal rutile. Since rutile is difficult to be modified by later hydrothermal alteration after its formation, it is an ideal mineral for studying the hydrothermal migration and replacement pathways of porphyry mineralization systems.

[0031] The temperature of porphyry copper deposits decreases from the hydrothermal center to the periphery. Previous researchers found through experimental petrological studies that when the pressure is close to 1 kbar, the zirconium in rutile and the temperature satisfy the following relationship: By utilizing the change in zirconium content in rutile, we can quickly lock the migration direction of hydrothermal fluid in space and thus determine the migration path.

[0032] However, it is necessary to further determine whether the hydrothermal fluid has mineralization potential. The decrease in oxygen fugacity during the evolution of hydrothermal fluids is an effective method to determine whether the hydrothermal fluid has mineralization potential. The decrease in oxygen fugacity during fluid evolution is affected by the crystallization of magnetite, and the crystallization of fluid magnetite will cause the titanium isotope of the fluid to increase. Therefore, by judging the change in titanium isotopes in the fluid, it can be a good indicator of whether the fluid has mineralization potential. 99% of the crystallized rutile in the fluid is titanium, which is an effective mineral for measuring the titanium isotope of the fluid. Therefore, by testing the zirconium content of rutile in different positions in space, the temperature distribution in space can be calculated, and then by testing the change in titanium isotopes in rutile, it can be determined whether the ore-forming fluid has a decrease in oxygen fugacity, and then the mineralization potential of the ore-forming fluid can be determined, and the migration path of the ore-forming hydrothermal fluid of the porphyry deposit can be determined.

[0033] Therefore, if Figure 1 As shown, the embodiment of the present application provides a method for determining the migration path of mineralization hydrothermal fluid using rutile, comprising:

[0034] S1: Collect mineralized porphyry samples in the study area, pre-process each sample, and mark the location of rutile in each sample;

[0035] Specifically:

[0036] Sampling is carried out spatially according to the exploration grid, collecting mineralized porphyry samples, and recording the longitude and latitude coordinate data of each sampling point;

[0037] The collected samples were ground into laser sheets, and the output status, size and position of rutile in each sample were observed under a microscope and recorded.

[0038] S2: For each sample, measure the zirconium (Zr) content in each rutile to obtain the average zirconium content Zr of the sample. ppm , according to the average zirconium content Zr ppm Calculate the mineralization temperature of the sample; at the same time, the titanium dioxide content in the rutile of each sample can also be obtained, and the average titanium dioxide value of each sample can be obtained similarly.

[0039] Specifically:

[0040] The rutile in each sample was subjected to in-situ micro-area element analysis by laser ablation-inductively coupled plasma mass spectrometry to determine whether the Zr content in the rutile was uniform, to exclude the presence of Zr-rich inclusions in the rutile, and finally to retain the rutile without inclusions and measure the zirconium content in the rutile; since each sample contained multiple rutiles, the zirconium content values ​​of each rutile were averaged to calculate the average zirconium content Zr of the sample. ppm It should be noted that the detection of whether there are Zr-rich inclusions in rutile by laser ablation-inductively coupled plasma mass spectrometry in the present invention is a prior art, and the present invention will not elaborate on the specific detection process;

[0041] According to formula 1, the average zirconium content Zr of the combined sample ppm , calculate the mineralization temperature T of the sample:

[0042]

[0043] S3: Get the average titanium isotope value of the sample;

[0044] Specifically:

[0045] The in-situ titanium isotope of each rutile in the sample is tested by combining a femtosecond laser and a multi-collector inductively coupled plasma mass spectrometer. Since each sample contains multiple rutiles, the in-situ titanium isotope value of each rutile is averaged to obtain the average titanium isotope value of the sample.

[0046] S4: Determine the migration path of the ore-forming hydrothermal fluid based on the longitude and latitude data, mineralization temperature and average titanium isotope value of each sample.

[0047] Specifically:

[0048] Based on the evolution direction of the mineralization temperature values ​​of multiple samples from high temperature to low temperature, the cooling direction of the mineralization fluid is determined. If the mineralization temperature of multiple samples does not change in space, it indicates that there is no hydrothermal migration channel in the study area;

[0049] Linear fitting processing was performed on the mineralization temperature and average titanium isotope value of multiple samples. If the mineralization temperature and the average titanium isotope value of the sample are negatively correlated, it indicates the presence of magnetite crystallization and reduced oxygen fugacity, representing that this series is the mineralization hydrothermal migration path. The evolution direction of the mineralization temperature values ​​of multiple samples from high temperature to low temperature is the direction of the mineralization hydrothermal migration path of the study area. If the mineralization temperature and the average titanium isotope value of the sample are uncorrelated or positively correlated, it indicates that there is no mineralization hydrothermal evolution in the study area and it has no mineralization potential.

[0050] Example 1

[0051] Step 1: Data collection and sample collection in the study area and its surrounding areas.

[0052] A porphyry copper mine in the Gangdise mineralization belt was selected as the research area. Sampling was carried out in space according to the exploration grid of 100m×100m, and 60 mineralization porphyry samples were collected. The length, width and height of the samples were about 3cm*5cm*8cm. Each sampling point needs to collect longitude and latitude coordinate data, take field photos, detailed field records, lithology, alteration and mineralization characteristics of each sample, etc.

[0053] Step 2: Sample pretreatment.

[0054] The collected samples were ground into laser sheets, and the characteristics of the rutile in each sample were observed under a microscope. The production status, size, and location of each rutile were recorded in detail.

[0055] Step 3: Calculation of the mineralization temperature value of the sample.

[0056] The rutile in each sample was subjected to in-situ micro-area element analysis by laser ablation-inductively coupled plasma mass spectrometry. More than 10 rutile particles were analyzed in one sample, and the titanium dioxide content and zirconium content of each rutile were recorded, and the average zirconium content Zr of each sample was obtained. ppm and average TiO2 values.

[0057] The signal curve of laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) was used to determine whether the zirconium content in rutile was uniform, and the presence of zirconium-rich inclusions in rutile was excluded. Finally, the data without zirconium-rich inclusions were retained, and then the average zirconium content Zr of the sample was calculated. ppm The average zirconium content Zr in each sample ppmSubstitute into the formula In the above data, the mineralization temperature of each porphyry sample is calculated.

[0058] Step 4: Average titanium isotope test of the sample.

[0059] In situ titanium isotope analysis of the samples was performed by combining femtosecond laser (fs-LA) and multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS).

[0060] The routine data acquisition consisted of 120 cycles, each set to 0.524s. The first 25 cycles were used to monitor the instrument background, and the subsequent 95 cycles were used to collect the sample signal. The actual titanium isotope ratio was calculated from the signal value of the stable 50-60 cycles. The laser ablation parameters were 1Hz, 20μm, 3.2Jcm -2 , calculate the average titanium isotope (δ 49 Ti) value.

[0061] Step 5: Determine the migration path of mineralizing hydrothermal fluids.

[0062] According to the latitude and longitude coordinates, mineralization temperature and average titanium isotope value of each sample, the migration path of the mineralization hydrothermal fluid is determined. The test data information of each sample is shown in Table 1. The linear fitting results of the mineralization temperature and average titanium isotope value of each sample are shown in Figure 1 shown by Figure 1 It can be seen that the mineralization temperature values ​​and average titanium isotope values ​​of multiple samples in this study area are negatively correlated, indicating that there is magnetite crystallization and reduced oxygen fugacity in the study area, and it has mineralization potential. The mineralization temperature values ​​of multiple sample collection points evolve from high temperature to low temperature, which is the direction of the mineralization hydrothermal migration path in the study area. Combined with the longitude and latitude values ​​of each sample, the location of the migration path in space is depicted.

[0063] Table 1

[0064]

[0065]

[0066] In the present invention, rock samples are collected in a space system, and laser ablation-inductively coupled plasma mass spectrometry is used to analyze the trace elements and titanium isotopes of rutile at different positions in space, and the formation temperature of rutile at each position is calculated. According to the changes in temperature and titanium isotopes, the direction of migration of mineralizing hydrothermal fluids is finally accurately determined, and the porphyry mineralization system is better explored for prospecting breakthroughs. This is an economical and efficient new method for mineral exploration, which saves more than 90% of funds and more than 80% of time compared with traditional exploration methods.

[0067] The above are only exemplary embodiments of the present disclosure and cannot be used to limit the scope of the present disclosure. That is, any equivalent changes and modifications made according to the teachings of the present disclosure are still within the scope of the present disclosure. After considering the disclosure of the specification and the truth of practice, those skilled in the art will easily think of other embodiments of the present disclosure.

[0068] This application is intended to cover any variation, use or adaptation of the present disclosure, which follows the general principles of the present disclosure and includes common knowledge or customary technical means in the art not described in the present disclosure. The description and examples are to be regarded as exemplary only, and the scope and spirit of the present disclosure are defined by the claims.

Claims

1. A method for determining the migration path of ore-forming hydrothermal fluids using rutile, characterized in that: The method comprises the following steps: S1: Collect mineralized porphyry samples in the study area, pre-process each sample, and mark the location of rutile in each sample; S2: For each sample, measure the zirconium content in each rutile to obtain the average zirconium content Zr of the sample. ppm , according to the average zirconium content Zr ppm Calculate the mineralization temperature of the sample; S3: Get the average titanium isotope value of the sample; S4: Determine the migration path of the ore-forming hydrothermal fluid based on the mineralization temperature and average titanium isotope value of each sample.

2. A method for determining the migration path of ore-forming hydrothermal fluids using rutile as claimed in claim 1, characterized in that: Step S1 specifically includes: sampling in space according to the exploration grid, collecting mineralized porphyry samples, and recording the collection longitude and latitude coordinate data of each sample sampling point; The collected samples were ground into laser sheets, and the output status, size and position of rutile in each sample were observed and recorded.

3. A method for determining the migration path of ore-forming hydrothermal fluids using rutile as claimed in claim 1, characterized in that: Step S2 is specifically as follows: The rutile in each sample was subjected to in-situ micro-area element analysis to determine whether the Zr content in the rutile was uniform, and the presence of Zr-rich inclusions in the rutile was excluded. Finally, the rutile without inclusions was retained and the zirconium content in the rutile was measured; for samples containing multiple rutiles, the average value of the zirconium content in each rutile was calculated to obtain the average zirconium content Zr of the sample. ppm ; Combined with the average zirconium content of the sample Zr ppm , calculate the mineralization temperature of the sample.

4. A method for determining the migration path of ore-forming hydrothermal fluids using rutile as claimed in claim 3, characterized in that: The formula for calculating the sample mineralization temperature T is as follows:

5. A method for determining the migration path of ore-forming hydrothermal fluids using rutile as claimed in claim 1, characterized in that: Step S3 is specifically as follows: The in-situ titanium isotope of each rutile in the test sample is measured; for a sample containing multiple rutiles, the in-situ titanium isotope value of each rutile measured is averaged to obtain the average titanium isotope value of the sample.

6. A method for determining the migration path of ore-forming hydrothermal fluids using rutile as claimed in claim 1, characterized in that: Step S4 is specifically as follows: Analyze whether the mineralization temperature of each sample changes in space. If there is no change, it means that there is no hydrothermal migration channel in the study area; if there is, then: Linear fitting is performed on the mineralization temperature and average titanium isotope value of multiple samples. If the mineralization temperature and average titanium isotope value of the samples are negatively correlated, it means that the study area has mineralization potential. The evolution direction of the mineralization temperature values ​​of multiple samples from high temperature to low temperature is the direction of the migration path of the mineralization hydrothermal fluid. If the mineralization temperature and average titanium isotope value of the samples are uncorrelated or positively correlated, it indicates that the study area has no mineralization potential and no hydrothermal migration pathway exists.

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