Milma-hydrothermal drive far-end deposit fluid migration path tracing method

Abstract

The invention discloses a magma-hydrothermal drive far-end ore deposit fluid migration path tracing method, and belongs to the technical field of geology and geochemistry, and the method comprises the following steps: S1, collecting geological data, and carrying out summary analysis; s2, performing field geological mapping and structural analysis on the typical fluid migration profile; s3, analyzing fluid inclusion and quartz in-situ trace elements in the quartz veins; s4, recovering the migration path of the ore-forming fluid; the magma-hydrothermal driven far-end ore deposit fluid migration path tracing method provided by the invention provides a solution thought for research on the fluid migration path of a far-end magma hydrothermal deposit.

Description

Technical Field

[0001] The invention relates to the technical field of geology and geochemistry, and in particular to a method for tracing the migration path of fluid in a remote ore deposit driven by magma-hydrothermal fluid. Background Art

[0002] The migration of ore-forming fluids in magmatic hydrothermal systems is the result of the combined effects of fluid mechanics, geology and geochemistry, and the process is very complex. Since magmatic-hydrothermal driven distal deposits are mostly generated in surrounding rock strata at a certain distance from the rock mass, the ore-forming fluids often undergo long-distance migration and are affected by complex geological conditions. At the same time, the evidence of fluid activity is mostly superimposed or destroyed by later mineralization. Tracing the migration path of ore-forming fluids has always been a difficult problem in the academic community, and the research foundation is relatively weak. Although isotope, geochemistry, geology and other methods are widely used in tracing fluid migration, they are also affected by factors such as isotope fractionation effect, multi-stage mineralization and fluid mixing, and the limitations of a single method, resulting in a decrease in the reliability and accuracy of the obtained data, which directly affects the accuracy of the tracing results. Summary of the invention

[0003] The purpose of the present invention is to provide a method for tracing the fluid migration path of a remote ore deposit driven by magma-hydrothermal fluid, so as to solve the problems existing in the above-mentioned background technology.

[0004] To achieve the above object, the present invention provides a method for tracing the fluid migration path of a remote ore deposit driven by magma-hydrothermal fluid, comprising the following steps:

[0005] Step S1, collect geological data and conduct summary analysis;

[0006] Step S2, performing field geological mapping and structural analysis on typical fluid migration profiles;

[0007] Step S3, analyzing the fluid inclusions and in-situ trace elements of quartz in the continuously developed quartz veins in the migration profile;

[0008] Step S4, restoring the migration path of the ore-forming fluid.

[0009] Preferably, the geological data in step S1 include the mineralization geological background, ore deposit geology, geochemistry and geophysical characteristics of the study area and mining area, and also include collecting literature related to the evolution of mineralizing fluids, understanding the research progress, methods and successful cases in this field at home and abroad, and laying the necessary foundation for carrying out the work of this project.

[0010] Preferably, step S2 specifically includes: conducting a field geological survey of the study area, identifying the characteristics of the regional and mining area strata, structures, magmatic rocks and ore bodies, focusing on statistical analysis of the regional and mining area structures (folds and faults), finding and observing the metamorphic deformation structure-alteration zoning in the thermal contact zone of the surrounding rock, the style of the filling quartz vein and the spatial distribution characteristics and other evidence of fluid activity, and identifying possible fluid migration channels; on this basis, combined with the regional metallogenic geological background, geochemistry and geophysical characteristics of the study area, comprehensively determine the ore-controlling rock mass, and design a representative fluid migration profile according to the principle of fluid mapping. The profile should start from the edge of the rock mass and extend through the mining area along the main axis of the surrounding rock deformation structure-alteration zoning; the hydrothermal quartz veins of the same mineralization period that are widely developed on the profile are taken as the main research objects, and the quartz vein samples on and on both sides of the profile are collected as evenly and equidistantly as possible for the next step of analysis and testing.

[0011] Preferably, step S3 includes: petrographic observation and thermodynamic analysis of fluid inclusions in quartz veins, laser Raman spectroscopy component analysis of individual fluid inclusions, and trace element analysis of quartz laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS).

[0012] Preferably, the petrographic observation and thermodynamic analysis of fluid inclusions in step S3 specifically include:

[0013] First, the collected quartz vein samples were made into double-sided polished inclusion slices, and different quartz generations were distinguished under a scanning electron microscope combined with cathodoluminescence (SEM-CL). The petrographic characteristics such as the size, morphology, distribution, type and filling degree of the primary fluid inclusions in the same generation of quartz were recorded. On this basis, the field of view where the inclusions to be measured were selected, removed with a micro drill, and the glass slices were separated from the samples in an acetone container; the samples to be tested were placed in the sample slot of the hot and cold stage, and quickly frozen to -70°C with liquid nitrogen until the inclusions were frozen, and then slowly heated to the freezing point temperature obtained when the last ice began to melt, and then heated again. When it was close to uniform, the uniform temperature was recorded, and the salinity, density and pressure of the fluid inclusions were calculated by the uniform temperature. The salinity calculation formula is:

[0014] S=1.78t m -0.0442t m 2 +0.000557t m 3 ;

[0015] Among them, t m is the freezing temperature;

[0016] The formula for calculating pressure is:

[0017] P1=P0×T1 / T0;

[0018] Among them, P0 = 219 + 2620 × S; T0 = 374 + 920 × S, P0 is the initial pressure, P1 is the mineralization pressure, T1 is the measured homogenization temperature, and T0 is the initial temperature;

[0019] The density is calculated as:

[0020] ρ=A+Bt m +Ct m 2 ;

[0021] Among them, A, B, and C are all functions of salinity, A=A0+A1S+A2S 2 ; B=B0+B1S+B2S 2 ; C=C0+C1S+C2S 2 ; and A0, A1, A2, B0, B1, B2, C0, C1, C2 are all dimensionless constants.

[0022] Preferably, the laser Raman spectroscopy component analysis of a single fluid inclusion in step S3 specifically includes: based on petrographic observation and thermodynamic analysis of fluid inclusions, using a laser Raman probe to analyze the liquid phase (HCO3 - 、CO3 2- 、Na + , K + , Ca 2+ , H2O), gas phase (H2O, CO2, CH4, N2, H2) or solid phase composition is determined, that is, by directly comparing with standard Raman spectra of known molecular groups and mineral structures, qualitative or quantitative analysis of molecular composition and molecular ligand structure information can be achieved, and the variation law of fluid inclusion composition in different spatial positions can be found out; the petrographic observation and thermodynamic analysis of fluid inclusions are combined with the laser Raman spectroscopy component analysis of a single fluid inclusion, and the temperature, salinity, pressure, density and composition variation characteristics of the same period of fluid events on the migration profile are compared, and the spatial evolution law of fluids is summarized.

[0023] Preferably, the LA-ICP-MS trace element analysis of quartz in step S3 specifically includes: making quartz vein samples at different spatial positions on the fluid migration profile into standard polished light sheet targets, observing the shape of quartz crystals under a scanning electron microscope with cathode luminescence (SEM-CL), distinguishing different quartz generations, and performing LA-ICP-MS in situ trace element analysis on coarse-grained quartz of the same generation without obvious visible inclusions, finding out the variation patterns of the trace element content and geochemical characteristic values ​​(mainly including Ti, Li, Al, As, Sb, Li / Al) of the quartz of each sample on a spatial scale, extracting the indicative information on the fluid migration path contained therein, and comparing and verifying it with the results of fluid inclusion analysis, so as to comprehensively obtain the ore-forming fluid migration model of the study area.

[0024] Preferably, step S4 specifically includes: based on the field geological survey of step S2 and the analysis and test results of step S3, integrating the previous research results, finding out the spatial distribution characteristics and evolution laws of the composition, temperature, salinity, etc. of the ore-forming fluid and the distribution characteristics of the temperature field and strain field of the surrounding rock, identifying the fluid channels, and reconstructing the fluid migration path.

[0025] Therefore, the present invention adopts the above-mentioned magma-hydrothermal driven remote ore deposit fluid migration path tracing method, which has the following beneficial effects:

[0026] (1) This tracing method can accurately identify the migration path of magmatic-hydrothermal fluids from the source area to the ore deposit, which helps to better understand the formation mechanism of the ore deposit and make mineralization predictions;

[0027] (2) By tracing the fluid migration path, we can deeply study the changes in fluid chemical composition, temperature, pressure and other parameters during the mineralization process and reveal the mechanism of mineralization;

[0028] (3) This method provides new means and data support for scientific research in the fields of mineralogy and geochemistry, and promotes the development of related disciplines.

[0029] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The present invention is a flow chart of a method for tracing the migration path of fluid in a remote ore deposit driven by magma-hydrothermal fluid. DETAILED DESCRIPTION

[0031] The following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] like Figure 1 As shown, a method for tracing the fluid migration path of a remote ore deposit driven by magma-hydrothermal fluid includes the following steps:

[0033] Step S1, collect geological data and conduct summary analysis;

[0034] Comprehensively collect basic geological data and relevant literature on the study area and mining area, compile geological maps, drill core and trench exploration data, analyze regional and mining area geophysical and geochemical data, master the mineralization geological background of the study area and mining area, and the geological, geochemical and geophysical characteristics of the ore deposits; at the same time, collect literature related to the evolution of ore-forming fluids, understand the research progress, methods and successful cases in this field at home and abroad, and lay the necessary foundation for carrying out this project.

[0035] Step S2, performing field geological mapping and structural analysis on typical fluid migration profiles;

[0036] Targeted field geological surveys were conducted in the study area to further identify the characteristics of the regional and mining area strata, structures, magmatic rocks and ore bodies, with a focus on statistical analysis of regional and mining area structures (folds and faults), to find and observe evidence of fluid activity such as metamorphic deformation structures-alteration zoning in the thermal contact zone of the surrounding rock, the style of filling veins (quartz veins) and spatial distribution characteristics, and to identify possible fluid migration pathways; on this basis, combined with the regional metallogenic geological background, geochemistry and geophysical characteristics of the study area, the ore-controlling rock mass was comprehensively determined, and a representative fluid migration profile was designed according to the principle of fluid mapping. The profile starts from the edge of the rock mass and extends through the mining area along the main axis of the surrounding rock deformation structure-alteration zoning; the hydrothermal quartz veins of the same mineralization period that are widely developed on the profile are taken as the main research objects, and quartz vein samples on and on both sides of the profile are collected as evenly and equidistantly as possible for the next step of analysis and testing.

[0037] Step S3, analyzing the fluid inclusions and in-situ trace elements of quartz in the quartz veins developed in the fluid migration profile;

[0038] (1) Petrographic observation and thermodynamic analysis of fluid inclusions

[0039] The quartz vein samples were ground into double-sided polished inclusion slices, and different quartz generations were distinguished under scanning electron microscopy combined with cathodoluminescence (SEM-CL). The size, morphology, distribution, type and filling degree of primary fluid inclusions in quartz of the same generation were observed and recorded. After photography and positioning, the samples were sent to a hot and cold stage to measure the uniform temperature of the primary fluid inclusions and calculate the thermodynamic parameters such as salinity, density and pressure of the fluid inclusions.

[0040] The specific steps of measuring the temperature of inclusions are as follows: first, the collected quartz vein samples are made into double-sided polished inclusion slices, and the petrographic characteristics such as the size, shape, distribution, type and filling degree of the inclusions are observed under SEM-CL. On this basis, the field of view where the representative inclusions need to be measured is selected, and they are removed with a micro drill, and the glass slices are separated from the samples in an acetone container; the sample to be tested is placed in the sample slot of the hot and cold stage, and liquid nitrogen is used to quickly freeze it to -70°C until the inclusions are frozen, and then the temperature is slowly raised to the freezing point temperature obtained when the last ice begins to melt, and then the temperature is raised again. When it is close to uniformity, the uniform temperature is recorded, and the salinity (wt.% NaCl) of the two-phase (liquid-rich phase gas-liquid) aqueous solution inclusions is recorded. eqv ) is calculated using the following formula:

[0041] S=1.78t m -0.0442t m 2 +0.000557t m 3 ;

[0042] Among them, t m is the freezing point temperature; S is between 1% and 30%;

[0043] For two-phase inclusions, the fluid pressure is calculated based on the homogenization temperature of the inclusions and the fluid salinity using the fluid pressure empirical formula:

[0044] P1=P0×T1 / T0;

[0045] Among them, P0 = 219 + 2620 × S; T0 = 374 + 920 × S, P0 is the initial pressure (Pa), P1 is the mineralization pressure (Pa), T1 is the measured homogenization temperature (℃), and T0 is the initial temperature (℃);

[0046] The density is calculated as:

[0047] ρ=A+Bt m +Ct m 2 ;

[0048] Where ρ is the density of the brine solution (g / cm 3 ), A, B, and C are all functions of salinity, A=A0+A1S+A2S 2 ; B=B0+B1S+B2S 2 ; C=C0+C1S+C2S 2 ; and A0, A1, A2, B0, B1, B2, C0, C1, C2 are all dimensionless constants.

[0049] (2) Laser Raman spectroscopy analysis of single fluid inclusion components

[0050] Based on petrographic observation and thermodynamic analysis of fluid inclusions, a laser Raman probe was used to investigate the liquid phase (HCO3 - 、CO3 2- 、Na + , K + , Ca 2 + , H2O), gas phase (H2O, CO2, CH4, N2, H2) or solid phase composition is determined, that is, by directly comparing with standard Raman spectra of known molecular groups and mineral structures, qualitative or quantitative analysis of molecular composition and molecular ligand structure information can be achieved, and the variation law of fluid inclusion composition in different spatial positions can be found out; the petrographic observation and thermodynamic analysis of fluid inclusions are combined with the laser Raman spectroscopy component analysis of a single fluid inclusion, and the temperature, salinity, pressure, density and composition variation characteristics of the same period of fluid events on the migration profile are compared, and the spatial evolution law of fluids is summarized.

[0051] (3) Quartz LA-ICP-MS trace element analysis

[0052] The contents of trace elements Li, Al, Ti, Ge|, As, Sb, etc. in quartz in magmatic-hydrothermal systems are mainly controlled by cooling along the fluid evolution path. In S-type and A-type granite-greisen systems, the Li / Al ratio of magmatic quartz is high, and the Li and Al contents of hydrothermal quartz gradually decrease due to cooling along the fluid evolution path; in I-type porphyry-ephemeral low-temperature hydrothermal systems, the Li / Al ratio of magmatic quartz is low, and hydrothermal quartz has gradually increasing Li and Al contents controlled by cooling along the fluid evolution path. In various magmatic hydrothermal systems, the changes in the contents of Ti, Ge, As, and Sb are generally positively correlated with Al and Li. Therefore, according to the spatial evolution of the contents of Li, Al, Ti, Ge|, As, and Sb in quartz, the fluid migration path can be traced.

[0053] Quartz vein samples at different spatial positions on the fluid migration profile were made into standard polished light sheet targets. The quartz crystal shapes were observed under SEM-CL to distinguish different quartz generations. LA-ICP-MS in situ trace element analysis was performed on coarse-grained quartz of the same generation without obvious visible inclusions. The variation patterns of trace element content and geochemical characteristic values ​​(Ti, Li, Al, As, Sb, Li / Al) of quartz in each sample on the spatial scale were found out, and the indicative information on the fluid migration path contained therein was extracted. The information was compared and verified with the results of fluid inclusion analysis, and the migration mode of ore-forming fluid in the study area was comprehensively obtained.

[0054] Step S4, restoring the migration path of the ore-forming fluid.

[0055] Based on the field geological survey of step S2 and the analysis and test results of step S3, and combining the previous research results, the spatial distribution characteristics and evolution laws of the composition, temperature, salinity, etc. of the ore-forming fluid and the distribution characteristics of the temperature field and strain field of the surrounding rock are found out, the fluid channels are identified, and the fluid migration path is reconstructed.

[0056] Therefore, the present invention adopts the above-mentioned magma-hydrothermal driven remote deposit fluid migration path tracing method to provide a solution for the study of fluid migration path of remote magmatic hydrothermal deposits.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for tracing the fluid migration path of a remote ore deposit driven by magma-hydrothermal fluid, characterized in that: The following steps are involved: Step S1, collect geological data and conduct summary analysis; Step S2, performing field geological mapping and structural analysis on typical fluid migration profiles; Step S3, analyzing the fluid inclusions in the quartz veins and the in-situ trace elements of the quartz; Step S4, restoring the migration path of the ore-forming fluid.

2. A method for tracing the fluid migration path of a remote ore deposit driven by magma-hydrothermal fluid according to claim 1, characterized in that: The geological data in step S1 include the mineralization geological background, ore deposit geology, geochemistry and geophysical characteristics of the study area and the mining area, and also include the collection of data related to the evolution of mineralization fluids.

3. A method for tracing the fluid migration path of a remote ore deposit driven by magma-hydrothermal fluid according to claim 2, characterized in that: Step S2 specifically includes: conducting field geological surveys in the study area, identifying the characteristics of the regional and mining area strata, structures, magmatic rocks and ore bodies, especially conducting statistical analysis of the regional and mining area structures, finding and observing the metamorphic deformation structure-alteration zoning of the surrounding rock thermal contact zone, the style of the filling quartz veins and the spatial distribution characteristics; on this basis, combined with the regional metallogenic geological background, geochemistry and geophysical characteristics of the study area, comprehensively determine the ore-controlling rock mass, and design a fluid migration profile according to the fluid mapping principle. The profile starts from the edge of the rock mass and extends through the mining area along the main axis of the surrounding rock deformation structure-alteration zoning.

4. A method for tracing the migration path of fluid in a remote ore deposit driven by magma-hydrothermal fluid according to claim 3, characterized in that: Step S3 includes: petrographic observation and thermodynamic analysis of fluid inclusions, laser Raman spectroscopy component analysis of a single fluid inclusion, and trace element analysis of quartz laser ablation-inductively coupled plasma mass spectrometry.

5. A method for tracing the fluid migration path of a remote ore deposit driven by magma-hydrothermal fluid according to claim 4, characterized in that: The petrographic observation and thermodynamic analysis of fluid inclusions in step S3 specifically include: First, the collected quartz vein samples were made into double-sided polished inclusion slices, and different quartz generations were distinguished under a scanning electron microscope with cathode luminescence, and the petrographic characteristics of primary fluid inclusions in the same generation of quartz were recorded. On this basis, the field of view where the inclusions to be measured were selected, removed with a micro drill, and the glass slices were separated from the samples in an acetone container; the samples to be tested were placed in the sample slot of the hot and cold stage, and quickly frozen to -70°C with liquid nitrogen until the inclusions were frozen, and then slowly heated to the freezing point temperature obtained when the last ice began to melt, and then heated again, and the uniform temperature was recorded. The salinity, density and pressure of the fluid inclusions were calculated by the uniform temperature. The salinity calculation formula is: S=1.78t m -0.0442t m 2 +0.000557t m 3 ; Among them, t m is the freezing temperature; The formula for calculating pressure is: P1=P0×T1 / T0; Among them, P0 = 219 + 2620 × S; T0 = 374 + 920 × S, P0 is the initial pressure, P1 is the mineralization pressure, T1 is the measured homogenization temperature, and T0 is the initial temperature; The density is calculated as: ρ1A+Bt m +Ct m 2 100. Among them, A, B, and C are all functions of salinity, A=A0+A1S+A2S 2 ; B=B0+B1S+B2S 2 ; C=C0+C1S+C2S 2 ; and A0, A1, A2, B0, B1, B2, C0, C1, C2 are all dimensionless constants.

6. A method for tracing the fluid migration path of a remote ore deposit driven by magma-hydrothermal fluid according to claim 5, characterized in that: The laser Raman spectral component analysis of a single fluid inclusion in step S3 specifically includes: based on petrographic observations and thermodynamic analysis of fluid inclusions, using a laser Raman probe to measure the liquid, gas or solid phase components of a single primary fluid inclusion in the same generation of quartz in inclusion slices of different quartz vein samples, to find out the variation pattern of the fluid inclusion components in different spatial positions; combining petrographic observations and thermodynamic analysis of fluid inclusions with laser Raman spectral component analysis of a single fluid inclusion, to compare the temperature, salinity, pressure, density and composition variation characteristics of the same period of fluid events on the migration profile, and to summarize the spatial evolution pattern of the fluid.

7. A method for tracing the migration path of fluid in a remote ore deposit driven by magma-hydrothermal fluid according to claim 6, characterized in that: The quartz laser ablation-inductively coupled plasma mass spectrometry trace element analysis in step S3 specifically includes: making quartz vein samples at different spatial positions on the fluid migration profile into standard polished light sheet targets, observing the shape of quartz crystals under a scanning electron microscope with cathode luminescence to distinguish different quartz generations, and performing in situ trace element analysis by laser ablation-inductively coupled plasma mass spectrometry on coarse-grained quartz of the same generation without obvious visible inclusions, finding out the variation patterns of the trace element content and geochemical characteristic values ​​of the quartz of each sample on a spatial scale, extracting the indicative information on the fluid migration path contained therein, and comparing and verifying the results of the fluid inclusion analysis to comprehensively obtain the ore-forming fluid migration model of the study area.

8. A method for tracing the migration path of fluid in a remote ore deposit driven by magma-hydrothermal fluid according to claim 7, characterized in that: Step S4 specifically includes: based on the field geological survey of step S2 and the analysis and test results of step S3, finding out the spatial distribution characteristics and evolution laws of the ore-forming fluid and the distribution characteristics of the temperature field and strain field of the surrounding rock, identifying the fluid migration channel, and reconstructing the fluid migration path.

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