Method suitable for judging fluid migration direction of hydrothermal deposit

Abstract

The invention discloses a method for judging the fluid migration direction of a hydrothermal deposit. The method comprises the following steps: selecting a hydrothermal deposit with an association relationship in a research area; a hydrothermal mineral sample is collected from each hydrothermal deposit, the metallogenic period corresponding to each hydrothermal deposit is determined and marked, and the hydrothermal deposit is divided into a pre-metallogenic period, a metallogenic period and a post-metallogenic period based on the metallogenic period; respectively carrying out stable isotope testing on the hydrothermal mineral samples before mineralization, during mineralization and after mineralization, and judging mineral stable isotope change rules corresponding to the hydrothermal mineral samples at different mineralization stages before mineralization, during mineralization and after mineralization; comparing and researching mineral stable isotope change rules of hydrothermal mineral samples of more than two hydrothermal deposits in each mineralization stage, and taking a direction in which the mineral stable isotope change rules in the hydrothermal deposits tend to be consistent as a fluid migration direction; selecting another isotope for verification; according to the method, the change rule of the stable isotope is used as an effective means for source tracing and source tracing of the deposit forming hydrothermal solution.

Description

Technical Field

[0001] The present invention relates to the technical field of fluid migration in ore deposits, and in particular to a method for determining the direction of fluid migration in hydrothermal ore deposits. Background Art

[0002] The formation of hydrothermal deposits is inseparable from the participation of ore-forming fluids. Fluid inclusions, as direct records of magmatic and hydrothermal fluid activity trapped in mineral lattices, have long been recognized and utilized by geologists. Since the study of fluid inclusions was introduced into the field of Chinese geology in the 1960s, the continuous advancement and enrichment of research methods have led to a continuous increase in the depth and level of research in ore deposits and other fields. The study of fluid inclusions can provide accurate information on the physical and chemical properties of ore-forming fluids, such as temperature, salinity, composition, pressure, density, pH, and Eh. Therefore, it is one of the most important means and methods for studying the properties of ore-forming fluids, their temporal and spatial evolution characteristics, the depth of rock formation and mineralization, and the mechanism of mineralization in hydrothermal mineralization systems.

[0003] At present, the methods for judging the direction of fluid migration in hydrothermal deposits are mostly based on accurate information on the physical and chemical properties of the ore-forming fluid, such as temperature, salinity, composition, pressure, density, pH and Eh. There are many factors to judge, which makes the judgment procedure complicated. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for determining the direction of fluid migration in hydrothermal deposits, so as to solve the technical problem that the methods for determining the direction of fluid migration in the prior art are mostly based on accurate information on the physical and chemical properties of the ore-forming fluid, such as temperature, salinity, composition, pressure, density, pH and Eh, and there are many judgment factors, which leads to complex judgment procedures and methods.

[0005] In order to solve the above technical problems, the present invention specifically provides the following technical solutions:

[0006] A method for determining the direction of fluid migration in a hydrothermal deposit, comprising the following steps:

[0007] Step 100: Select an area with the same metallogenic background and the same hydrothermal system as a study area, and select two or more hydrothermal deposits with correlation within the study area;

[0008] Step 200: Collect hydrothermal mineral samples from each hydrothermal deposit, analyze the hydrothermal mineral samples respectively, determine and mark the mineralization period corresponding to each hydrothermal mineral sample, and determine the mineralization sequence corresponding to the ore minerals in the hydrothermal deposit based on the mineralization period of each hydrothermal mineral sample and the spatial relative position of each hydrothermal mineral sample in the hydrothermal deposit;

[0009] Step 300: Conduct stable isotope tests on hydrothermal mineral samples before, during, and after mineralization to determine the stable isotope variation patterns of hydrothermal mineral samples at different mineralization stages.

[0010] Step 400: Comparing and studying the variation patterns of stable isotopes of hydrothermal mineral samples in two or more selected hydrothermal deposits, taking the direction in which the variation patterns of stable isotopes of minerals in the hydrothermal deposits tend to be consistent as the direction of fluid migration, and taking the opposite direction of the fluid migration direction as the source area direction of the ore-forming fluid of the hydrothermal deposit;

[0011] Step 500: Verify the mineral stable isotope variation pattern of different mineralization periods obtained in step 300 and the fluid migration direction obtained in step 400 by the direction of variation of the sulfur isotope content in the hydrothermal mineral samples in the hydrothermal deposit.

[0012] As a preferred solution of the present invention, in step 100, the method for selecting an area with the same metallogenic background and the same hydrothermal system as the study area is as follows:

[0013] Based on regional geological survey data and geophysical and geochemical data, a study area with the same mineralization background is selected, and geochemical exploration work is carried out in the study area to confirm that the selected study area is in the same tectonic-hydrothermal background;

[0014] Hydrothermal alteration characteristics or deposit types are used to determine whether the hydrothermal deposits in the selected study area belong to the same hydrothermal system, and two or more hydrothermal deposits in the same hydrothermal system are selected.

[0015] As a preferred embodiment of the present invention, the method of selecting two or more hydrothermal deposits of the same hydrothermal system is as follows: selecting two or more hydrothermal deposits that are spatially correlated in the study area;

[0016] Wherein, the selected space includes vertical space and / or horizontal space;

[0017] Two or more hydrothermal deposits with an associated relationship refer to hydrothermal deposits having the same geochemical anomalies and being located in the same regional structure.

[0018] As a preferred embodiment of the present invention, in step 200, a mineral deposit study is conducted on two or more selected hydrothermal deposits, hydrothermal mineral samples are collected from the hydrothermal deposits, and based on the macroscopic and microscopic characteristics of the ore minerals in the hydrothermal deposits, the hydrothermal mineral samples in the hydrothermal deposits are classified into hydrothermal minerals in different mineralization stages, namely, pre-ore formation, mineralization period, and post-ore formation. The specific implementation method is as follows:

[0019] collecting a plurality of hydrothermal mineral samples from the hydrothermal deposit, and grinding all the hydrothermal mineral samples into thin slices;

[0020] Thin sections made from all hydrothermal mineral samples are identified under a transflective microscope to mark the mineralization sequence of hydrothermal mineral samples in different mineralization stages and determine the current mineralization stage of the hydrothermal mineral samples;

[0021] Mark the specific location of the collected hydrothermal mineral samples at the hydrothermal deposit, and the mineralization stage corresponding to the specific location.

[0022] As a preferred embodiment of the present invention, in step 300, stable isotope testing is performed on hydrothermal mineral samples collected from each hydrothermal deposit, or stable isotope testing is performed on single minerals selected from each hydrothermal deposit to determine stable isotope characteristics formed at different mineralization stages in each hydrothermal deposit.

[0023] The stable isotope test results are marked on the sampling locations of the hydrothermal deposit to determine the variation characteristics of the hydrothermal mineral samples corresponding to the different mineralization stages before, during and after mineralization.

[0024] As a preferred embodiment of the present invention, the method for performing stable isotope testing on hydrothermal mineral samples collected from each hydrothermal deposit is as follows:

[0025] Using a stable gas isotope mass spectrometer to detect hydrogen and oxygen isotopes in each hydrothermal mineral sample, and marking the detection results of the hydrogen and oxygen isotopes with the spatial relative position of the hydrothermal mineral sample in the hydrothermal deposit;

[0026] Determining changes in the hydrothermal process of the hydrothermal deposit based on the variation patterns of the hydrogen and oxygen isotope content ranges corresponding to the hydrogen and oxygen isotope content ranges at different spatial relative positions of the hydrothermal deposit;

[0027] According to the hydrogen and oxygen isotope content ranges corresponding to the same mineralization stage in two or more selected hydrothermal deposits, the fluid migration directions corresponding to the same mineralization stage in different hydrothermal deposits are determined based on the variation pattern of the hydrogen and oxygen isotope content ranges.

[0028] As a preferred embodiment of the present invention, the hydrogen and oxygen isotope variation patterns of hydrothermal mineral samples corresponding to the same mineralization stage in two or more hydrothermal deposits are compared, and the direction in which the hydrogen and oxygen isotope variation patterns tend to be consistent is taken as the fluid migration direction, and the opposite direction of the fluid migration direction is taken as the source area direction of the mineralizing fluid of the hydrothermal deposit.

[0029] As a preferred embodiment of the present invention, in step 500, the method for verifying the variation pattern of stable isotopes of minerals in different metallogenic periods obtained in step 300 by the variation direction of the sulfur isotope content in the hydrothermal mineral sample in the hydrothermal deposit is as follows:

[0030] When collecting hydrothermal mineral samples from the hydrothermal deposit, the collection work is calibrated to the regional scale section, and the spatial relative position corresponding to each sampling work when collecting the hydrothermal mineral samples is determined;

[0031] Identifying the mineralization stage corresponding to the collected hydrothermal mineral sample;

[0032] Laser etching the collected hydrothermal mineral samples and conducting sulfur isotope testing;

[0033] Determine the sulfur isotope variation patterns corresponding to hydrothermal mineral samples in different mineralization stages.

[0034] As a preferred embodiment of the present invention, in step 500, the method for verifying the fluid migration direction obtained in step 400 by the direction of change in the sulfur isotope content in the hydrothermal mineral sample in the hydrothermal deposit is as follows:

[0035] Collecting hydrothermal mineral samples from two or more hydrothermal deposits and determining the mineralization stage corresponding to each hydrothermal mineral sample;

[0036] Laser etching the collected hydrothermal mineral samples and conducting sulfur isotope testing;

[0037] Determine the sulfur isotope variation patterns of the two or more hydrothermal deposits in each mineralization stage, take the direction in which the sulfur isotope variation patterns tend to be consistent as the fluid migration direction, and take the opposite direction of the fluid migration direction as the source area direction of the mineralizing fluid of the hydrothermal deposit.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] The present invention uses the changing pattern of stable isotopes as an effective means to trace the origin of hydrothermal fluids that form mineral deposits, and uses two or more stable isotopes to verify each other at the same time, which may effectively indicate the migration path or direction of regional mineral deposit fluids. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other implementation drawings based on the provided drawings without inventive effort.

[0041] Figure 1 Flowchart of the method for determining the migration direction of mineralization hydrothermal fluids provided in Example 1 of the present invention;

[0042] Figure 2 A specific flow chart for determining the migration direction of ore-forming hydrothermal fluids provided in Example 1 of the present invention;

[0043] Figure 3 For the selection of typical deposits in the area: the mineral structure of the Xiaohe gold mine ore and the formation sequence of the mineral formation;

[0044] Figure 4 The variation range and spatial distribution characteristics of H isotopes in typical deposits in the region, including Xiaohe Gold Mine, Wangzhuang Gold Mine, Gongguan Mercury-Antimony Mine, and Laojunmiao Gold Mine, as well as the spatial migration direction of fluids determined based on the regularity;

[0045] Figure 5 The stable sulfur isotope variation pattern of the metal sulfides formed from the early to the late period of the Xiaohe gold deposit;

[0046] Figure 6 This is the spatial variation pattern of stable isotopes formed by gold mines and mercury-antimony mines in the area. DETAILED DESCRIPTION

[0047] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0048] like Figure 1 and Figure 2 As shown, the present invention provides a method for determining the direction of fluid migration in hydrothermal deposits, comprising the following steps:

[0049] Step 100: Select an area with the same metallogenic background and the same hydrothermal system as a study area, and select two or more hydrothermal deposits with correlation within the study area;

[0050] Step 200: Collect hydrothermal mineral samples from each hydrothermal deposit, analyze the hydrothermal mineral samples, determine and mark the mineralization period corresponding to each hydrothermal mineral sample, and determine the mineralization sequence corresponding to the ore minerals in the hydrothermal deposit based on the mineralization period of each hydrothermal mineral sample and the spatial relative position of each hydrothermal mineral sample in the hydrothermal deposit;

[0051] Step 300: Conduct stable isotope tests on hydrothermal mineral samples before, during, and after mineralization to determine the stable isotope variation patterns of hydrothermal mineral samples at different mineralization stages.

[0052] Step 400: Compare and study the variation patterns of stable isotopes of hydrothermal mineral samples in two or more selected hydrothermal deposits, and use the direction in which the variation patterns of stable isotopes of the minerals in the hydrothermal deposits tend to be consistent as the direction of fluid migration, and use the opposite direction of the fluid migration direction as the source area direction of the ore-forming fluid of the hydrothermal deposit;

[0053] Step 500: Verify the mineral stable isotope variation pattern of different mineralization periods obtained in step 300 and the fluid migration direction obtained in step 400 by the variation direction of the sulfur isotope content in the hydrothermal mineral samples in the hydrothermal deposit.

[0054] In step 100, the method for selecting a hydrothermal deposit is as follows:

[0055] Through regional geological survey data and geophysical and geochemical exploration data, a study area with the same mineralization background was selected, and geochemical exploration work was carried out in the study area to determine that the selected study area was in the same tectonic-hydrothermal background.

[0056] Hydrothermal alteration characteristics or deposit types are used to determine whether the hydrothermal deposits in the selected study area belong to the same system, and then two or more hydrothermal deposits in the same hydrothermal system are selected.

[0057] Furthermore, the method of selecting two or more hydrothermal deposits of the same system is: from the study area, select two or more hydrothermal deposits with a correlation in vertical space and / or lateral space, wherein the two or more hydrothermal deposits with a correlation indicate that the geochemical anomalies of the hydrothermal deposits are the same and are located in the same regional structure.

[0058] By studying regional geological data, especially integrating relevant data and literature on typical mineral deposits, such as geochemical background, ore-controlling structures and geophysical data, and combining geochemical background, ore-controlling structures and geophysical data, we determine the mineral deposits that have the same geochemical anomalies in genesis and are located in the same regional structure.

[0059] In step 200, a mineral deposit study is conducted on two or more selected hydrothermal deposits, hydrothermal mineral samples are collected from the hydrothermal deposits, and based on the macroscopic and microscopic characteristics of the ore minerals in the hydrothermal deposits, the hydrothermal mineral samples at different mineralization stages in the hydrothermal deposits are classified as pre-mineralization, mineralization period, and post-mineralization hydrothermal minerals. The specific implementation method is as follows:

[0060] Collect multiple hydrothermal mineral samples from the hydrothermal deposit, and grind all the hydrothermal mineral samples into smooth thin slices;

[0061] Thin sections made from all hydrothermal mineral samples were identified under the microscope using a transflection microscope to mark the mineralization order and current mineralization stage of the hydrothermal mineral samples. The specific location of the collected hydrothermal mineral samples in the hydrothermal deposit and the corresponding mineralization stage of the location were also marked. The mineralization stages are: pre-mineralization, mineralization period, and post-mineralization.

[0062] When collecting multiple hydrothermal mineral samples from hydrothermal deposits, the collected hydrothermal mineral samples have a certain distribution relationship in space. Typical deposits are selected for research. The vein intersection relationship at the macro level is first determined, and then the generation sequence of each vein is determined. The mineralization stages at the macro level are divided. Based on the mineralization stages, the hydrothermal deposits can be divided into mineral ores of different stages: pre-mineralization, mineralization, and post-mineralization.

[0063] Hydrothermal mineral samples were collected from different periods before, during and after mineralization. The samples were identified indoors. Based on the microscopic mineral intersection relationship, the order of mineral formation during the mineralization period was determined, and a mineral formation sequence table was summarized, such as Figure 3 shown.

[0064] In step 300, stable isotope testing is performed on hydrothermal mineral samples collected from each hydrothermal deposit, or stable isotope testing is performed on single minerals selected from each hydrothermal deposit to determine the stable isotope characteristics formed at different mineralization stages in each hydrothermal deposit;

[0065] The stable isotope test results are marked on the sampling locations of hydrothermal deposits to determine the variation characteristics of hydrothermal mineral samples corresponding to different mineralization stages before, during, and after mineralization.

[0066] Furthermore, when collecting hydrothermal mineral samples from a hydrothermal deposit, the collection work is calibrated to a regional scale section, and the spatial relative position corresponding to each sampling work when collecting the hydrothermal mineral samples is determined;

[0067] Based on the changes in stable isotopes at the regional scale in different hydrothermal mineral samples, the changing patterns of stable isotopes at the regional profile scale are obtained, and the changing patterns of isotopes during the fluid migration process of hydrothermal deposits are displayed.

[0068] The method for conducting stable isotope testing on hydrothermal mineral samples collected from each hydrothermal deposit is as follows:

[0069] Stable gas isotope mass spectrometry is used to detect the hydrogen and oxygen isotopes in each hydrothermal mineral sample, and the detection results of hydrogen and oxygen isotopes are annotated to the spatial relative position of the hydrothermal mineral sample in the hydrothermal deposit;

[0070] Based on the hydrogen and oxygen isotope content ranges corresponding to different spatial relative positions of the same hydrothermal deposit, the changes in the hydrothermal process of the same hydrothermal deposit can be determined based on the variation patterns of the hydrogen and oxygen isotope content ranges;

[0071] According to the hydrogen and oxygen isotope content range corresponding to the same mineralization stage in two or more selected hydrothermal deposits, the fluid migration direction corresponding to the same mineralization stage of different hydrothermal deposits is determined based on the change law of the hydrogen and oxygen isotope content range. That is, the hydrogen and oxygen isotope change laws of hydrothermal mineral samples corresponding to the same mineralization stage in all two or more hydrothermal deposits are compared, and the direction in which the hydrogen and oxygen isotope change laws tend to be consistent is taken as the fluid migration direction, and the opposite direction of the fluid migration direction is taken as the source area direction of the mineralizing fluid of the hydrothermal deposit.

[0072] It should be noted that the stable isotopes involved in the present invention mainly refer to hydrogen and oxygen isotopes. The hydrogen and oxygen isotopes are determined using a stable gas isotope mass spectrometer / 253plus, using DZ / T 0184.19-1997 "Determination of Hydrogen Isotope Composition in Water by Zinc Reduction Method" and DZ / T 0184.20-1997 "Determination of Oxygen Isotope Composition in Water and Oxygen-Free Mineral Inclusions by Bromine Pentafluoride Method". The oxygen isotope test accuracy is ±0.2‰, and the hydrogen isotope test accuracy is ±2‰.

[0073] The principle of determining the migration direction of hydrothermal fluids by changes in hydrogen and oxygen isotopes is that the stable isotopes of hydrothermal fluids at different end members are different. To put it simply, mineral-bearing hydrothermal fluids have independent stable isotope compositions, and water-rock reactions occur in the strata along the fluid migration path during the migration process. Construction water often contains components of atmospheric precipitation, which will cause mixing of mineral-bearing hydrothermal fluids toward the atmospheric precipitation end, forming a changing hydrogen and oxygen isotope composition, which can reflect the migration path of the fluid.

[0074] In the present invention, the variation law of hydrogen and oxygen isotopes is utilized to determine the variation law of hydrogen and oxygen isotopes in different mineralization stages, as well as the variation law of hydrogen and oxygen isotopes in hydrothermal deposits in different directions, and further determine the direction of fluid migration between different hydrothermal deposits.

[0075] Specifically, the method for determining the changing rules of hydrogen and oxygen isotopes in different mineralization stages is as follows: determine the hydrogen and oxygen isotope contents in hydrothermal mineral samples corresponding to different mineralization stages in the same hydrothermal deposit, determine the isotope evolution trend, and compare the isotope change rules according to the relative position of the spatial scale in the hydrothermal deposit. Then, use the stable isotope equilibrium fractionation and kinetic fractionation characteristics to reveal the changes of stable isotopes in the hydrothermal process of the same hydrothermal deposit.

[0076] The method for determining the fluid migration direction between different hydrothermal deposits is as follows: compare the mineral stable isotope variation patterns of hydrothermal mineral samples corresponding to each mineralization stage in two or more hydrothermal deposits, and take the direction in which the mineral stable isotope variation patterns tend to be consistent as the fluid migration direction, that is, use the same type of stable isotopes of two or more hydrothermal deposits to compare and determine the fluid migration direction, select multiple stable isotopes for verification, determine the mineral stable isotope variation patterns of each mineralization stage of two or more hydrothermal deposits, take the direction in which the mineral stable isotope variation patterns tend to be consistent as the fluid migration direction, and take the opposite direction of the fluid migration direction as the source area direction of the mineralizing fluid of the hydrothermal deposit.

[0077] If the ranges of hydrogen isotope compositions during the mineralization period of different mineral deposits are inconsistent, an overall evolutionary trend can be determined based on their relative change trends. This study involves the hydrogen isotope change ranges of multiple mineral deposits during the mineralization period, and the evolutionary trends determined based on relative sizes. Based on the above trends, the stable isotope change laws of different mineral deposits are compared, and ultimately the stable isotope evolution trends between two or more mineral deposits are determined.

[0078] Determine the isotope evolution trend such as Figure 4 As shown, point A represents the Xiaohe gold mine, point B represents the Wangzhuang gold mine, point C represents the Gongguan mercury-antimony mine, and point D represents the Laojunmiao gold mine. Points A and B are located in the western spatial position of the study area, and points C and D are located in the eastern spatial position of the study area. By comparing the isotope variation patterns, it is determined that the fluid migration direction in the different hydrothermal deposits selected in the study area is from west to east.

[0079] In step 500, the method for verifying the variation pattern of stable isotopes of minerals in different metallogenic periods obtained in step 300 by the variation direction of sulfur isotope content in hydrothermal mineral samples in the hydrothermal deposit is as follows:

[0080] When collecting hydrothermal mineral samples from hydrothermal deposits, the collection work is calibrated to the regional scale section, and the spatial relative position corresponding to each sampling work when collecting hydrothermal mineral samples is determined;

[0081] Identify the mineralization stage corresponding to the collected hydrothermal mineral samples;

[0082] The collected hydrothermal mineral samples were laser etched and sulfur isotope tested;

[0083] Determine the sulfur isotope variation patterns corresponding to hydrothermal mineral samples in different mineralization stages.

[0084] Sulfur isotope analysis is performed using the LA-MC-ICP-MS method. The laser ablation system is a 193nm excimer laser ablation system (RESOlution M-50, ASI), using a multi-collector plasma mass spectrometer (NuPlasma 1700MC-ICP-MS). The S isotope resolution is greater than 12,000, the laser energy density is 3.6J / cm², the ablation frequency is 3Hz, and the ablation spot size is 30-37μm. The IAEA-S-1 standard sample is used for calibration, and the accuracy is better than 0.1‰. While the methods used by different laboratories may vary, the general principles are the same.

[0085] The Xiaohe gold mine in the study area was selected as a typical deposit to carry out stable S (sulfur) isotope testing. Figure 5 As shown in the figure, the sulfur isotope composition of each mineralization stage (early mineralization quartz vein stage, pyrite, arsenopyrite, quartz vein stage and quartz vein-sulfide stage) shows an evolution trend from high to low.

[0086] In step 500, the method for verifying the fluid migration direction obtained in step 400 by the change direction of the sulfur isotope content in the hydrothermal mineral sample in the hydrothermal deposit is as follows:

[0087] Collect hydrothermal mineral samples from two or more hydrothermal deposits and determine the mineralization stage corresponding to each hydrothermal mineral sample;

[0088] The collected hydrothermal mineral samples were laser etched and sulfur isotope tested;

[0089] Determine the sulfur isotope variation patterns of two or more hydrothermal deposits in each mineralization stage, take the direction in which the sulfur isotope variation patterns tend to be consistent as the fluid migration direction, and take the opposite direction of the fluid migration direction as the source area direction of the mineralizing fluid of the hydrothermal deposit.

[0090] The gold mines in the west and the mercury-antimony mines in the east of the study area were selected to compare their sulfur isotope ranges during the mineralization period. The content of sulfur isotopes in the range was determined to have an evolutionary trend from low to high from east to west. Figure 6 As shown, it specifically refers to the sulfur isotope ranges of the three mineralization periods of the Carlin-type gold deposit, Qingtonggou mercury-antimony deposit, and Gongguan mercury-antimony deposit in the area.

[0091] Combine Figure 5 The sulfur isotope composition of the three mineralization stages before mineralization, mineralization period and after mineralization shows an evolution trend from high to low. It is concluded that the migration direction of the mineralization hydrothermal fluid in the study area is from west to east, which is consistent with the Figure 4 The evolutionary trend is consistent with that formed.

[0092] Step 400 determined that the change in hydrogen and oxygen stable isotopes from west to east is negative. Based on regional data, the formations in this region have relatively negative isotopic compositions, indicating that the original fluid gradually mixed with a relatively negative fluid, and the fluid migration direction is from west to east, and vice versa. Regarding sulfur isotopes, for example, regional formations have relatively uniform isotopic compositions and are easily measured. Therefore, the exchange of sulfur with the formation during fluid migration will form a trend. This trend can be used to determine the fluid migration direction and to calibrate it with the previously reported hydrogen and oxygen isotopes.

[0093] This embodiment uses the changing pattern of stable isotopes as an effective means to trace the origin of hydrothermal fluids that form mineral deposits, and uses two or more stable isotopes to verify each other at the same time, which may effectively indicate the migration path or direction of regional mineral deposit fluids.

[0094] The above embodiments are merely exemplary embodiments of the present application and are not intended to limit the scope of the present application. The scope of protection of the present application is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present application within the essence and scope of protection of the present application, and such modifications or equivalent substitutions shall also be deemed to fall within the scope of protection of the present application.

Claims

1. A method for determining the direction of fluid migration in hydrothermal deposits, characterized in that: The following steps are involved: Step 100: Select an area with the same metallogenic background and the same hydrothermal system as a study area, and select two or more hydrothermal deposits with correlation within the study area; Step 200: Collect hydrothermal mineral samples from each hydrothermal deposit, analyze the hydrothermal mineral samples respectively, determine and mark the mineralization period corresponding to each hydrothermal mineral sample, and determine the mineralization sequence corresponding to the ore minerals in the hydrothermal deposit based on the mineralization period of each hydrothermal mineral sample and the spatial relative position of each hydrothermal mineral sample in the hydrothermal deposit; Step 300: Conduct stable isotope tests on hydrothermal mineral samples before, during, and after mineralization to determine the stable isotope variation patterns of hydrothermal mineral samples at different mineralization stages. Step 400: Comparing and studying the variation patterns of stable isotopes of hydrothermal mineral samples in two or more selected hydrothermal deposits, taking the direction in which the variation patterns of stable isotopes of minerals in the hydrothermal deposits tend to be consistent as the direction of fluid migration, and taking the opposite direction of the fluid migration direction as the source area direction of the ore-forming fluid of the hydrothermal deposit; Step 500: Verify the mineral stable isotope variation pattern of different mineralization periods obtained in step 300 and the fluid migration direction obtained in step 400 by the direction of variation of the sulfur isotope content in the hydrothermal mineral samples in the hydrothermal deposit.

2. The method for determining the direction of fluid migration in a hydrothermal deposit according to claim 1, wherein: In step 100, the method for selecting an area with the same metallogenic background and the same hydrothermal system as the study area is as follows: Based on regional geological survey data and geophysical and geochemical data, a study area with the same mineralization background is selected, and geochemical exploration work is carried out in the study area to confirm that the selected study area is in the same tectonic-hydrothermal background; Hydrothermal alteration characteristics or deposit types are used to determine whether the hydrothermal deposits in the selected study area belong to the same hydrothermal system, and two or more hydrothermal deposits in the same hydrothermal system are selected.

3. The method for determining the direction of fluid migration in a hydrothermal deposit according to claim 2, wherein: The method of selecting two or more hydrothermal deposits of the same hydrothermal system is as follows: selecting two or more hydrothermal deposits that are spatially correlated within the study area; Wherein, the selected space includes vertical space and / or horizontal space; Two or more hydrothermal deposits with an associated relationship refer to hydrothermal deposits having the same geochemical anomalies and being located in the same regional structure.

4. The method for determining the direction of fluid migration in a hydrothermal deposit according to claim 1, wherein: In step 200, a mineral deposit study is conducted on two or more selected hydrothermal deposits, hydrothermal mineral samples are collected from the hydrothermal deposits, and based on the macroscopic and microscopic characteristics of the ore minerals in the hydrothermal deposits, the hydrothermal mineral samples in the hydrothermal deposits are classified into hydrothermal minerals in different mineralization stages, namely, pre-ore formation, mineralization period, and post-ore formation. The specific implementation method is as follows: collecting a plurality of hydrothermal mineral samples from the hydrothermal deposit, and grinding all the hydrothermal mineral samples into thin slices; Thin sections made from all hydrothermal mineral samples are identified under a transflective microscope to mark the mineralization sequence of hydrothermal mineral samples in different mineralization stages and determine the current mineralization stage of the hydrothermal mineral samples; Mark the specific location of the collected hydrothermal mineral samples at the hydrothermal deposit, and the mineralization stage corresponding to the specific location.

5. The method for determining the direction of fluid migration in hydrothermal deposits according to claim 4, characterized in that: In step 300, stable isotope testing is performed on hydrothermal mineral samples collected from each hydrothermal deposit, or stable isotope testing is performed on single minerals selected from each hydrothermal deposit to determine stable isotope characteristics formed at different mineralization stages in each hydrothermal deposit; The stable isotope test results are marked on the sampling locations of the hydrothermal deposit to determine the variation characteristics of the hydrothermal mineral samples corresponding to the different mineralization stages before, during and after mineralization.

6. The method for determining the direction of fluid migration in a hydrothermal deposit according to claim 5, characterized in that: The method for performing stable isotope testing on hydrothermal mineral samples collected from each hydrothermal deposit is as follows: Using a stable gas isotope mass spectrometer to detect hydrogen and oxygen isotopes in each hydrothermal mineral sample, and marking the detection results of the hydrogen and oxygen isotopes with the spatial relative position of the hydrothermal mineral sample in the hydrothermal deposit; Determining changes in the hydrothermal process of the hydrothermal deposit based on the variation patterns of the hydrogen and oxygen isotope content ranges corresponding to the hydrogen and oxygen isotope content ranges at different spatial relative positions of the hydrothermal deposit; According to the hydrogen and oxygen isotope content ranges corresponding to the same mineralization stage in two or more selected hydrothermal deposits, the fluid migration directions corresponding to the same mineralization stage in different hydrothermal deposits are determined based on the variation pattern of the hydrogen and oxygen isotope content ranges.

7. The method for determining the direction of fluid migration in a hydrothermal deposit according to claim 6, characterized in that: Compare the hydrogen and oxygen isotope variation patterns of hydrothermal mineral samples corresponding to the same mineralization stage in two or more hydrothermal deposits, and take the direction in which the hydrogen and oxygen isotope variation patterns tend to be consistent as the fluid migration direction, and take the opposite direction of the fluid migration direction as the source area direction of the mineralizing fluid of the hydrothermal deposit.

8. The method for determining the direction of fluid migration in a hydrothermal deposit according to claim 6, wherein: In step 500, the method for verifying the variation pattern of stable isotopes of minerals in different metallogenic periods obtained in step 300 by the variation direction of the sulfur isotope content in the hydrothermal mineral sample in the hydrothermal deposit is as follows: When collecting hydrothermal mineral samples from the hydrothermal deposit, the collection work is calibrated to the regional scale section, and the spatial relative position corresponding to each sampling work when collecting the hydrothermal mineral samples is determined; Identifying the mineralization stage corresponding to the collected hydrothermal mineral sample; Laser etching the collected hydrothermal mineral samples and conducting sulfur isotope testing; Determine the sulfur isotope variation patterns corresponding to hydrothermal mineral samples in different mineralization stages.

9. The method for determining the direction of fluid migration in a hydrothermal deposit according to claim 8, characterized in that: In step 500, the method for verifying the fluid migration direction obtained in step 400 by the change direction of the sulfur isotope content in the hydrothermal mineral sample in the hydrothermal deposit is as follows: Collecting hydrothermal mineral samples from two or more hydrothermal deposits and determining the mineralization stage corresponding to each hydrothermal mineral sample; Laser etching the collected hydrothermal mineral samples and conducting sulfur isotope testing; Determine the sulfur isotope variation patterns of the two or more hydrothermal deposits in each mineralization stage, take the direction in which the sulfur isotope variation patterns tend to be consistent as the fluid migration direction, and take the opposite direction of the fluid migration direction as the source area direction of the mineralizing fluid of the hydrothermal deposit.

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