A comprehensive identification method of tin mineralization potential based on tourmaline

Abstract

The invention discloses a comprehensive discrimination method for tin mineralization potential based on tourmaline, comprising the following steps: 1) field geological survey, preliminary classification and sampling; 2) microscopic and detailed observation, and subdividing the types of tourmaline; 3) geochemical analysis; 4) preliminary discrimination of tin mineralization potential: preliminarily indicating the tin mineralization potential of a rock body or hydrothermal vein represented by the tourmaline according to the content of the Sn element; 5) magma evolution analysis: clarifying the genesis and evolution degree of different types of tourmaline, and finding out the spatial position of each type of tourmaline and the mineralization rock body; 6) final discrimination of tin mineralization potential: based on the genesis and evolution degree of the tourmaline determined in step 5 and the spatial position of each type of tourmaline and the mineralization rock body, combined with the preliminary discrimination result of the tin mineralization potential in step 4), finally discriminating the tin mineralization potential. The present invention uses the major element and trace element contents of widely distributed tourmaline as the main index for judging the tin mineralization potential, and combines the genesis, evolution degree and spatial position of tourmaline with the mineralization rock body to quickly and efficiently judge the tin mineralization potential, reduce the cost of tin ore exploration, improve exploration efficiency, and has important economic value.

Description

Technical Field

[0001] The invention relates to the technical field of tin ore exploration, and in particular to a comprehensive identification method of tin mineralization potential based on tourmaline. Background Art

[0002] Tin is a key mineral with a strategic position and is regarded as an indispensable rare metal mineral in various high-tech fields such as information security, energy reserves, aerospace, national defense and military industry. my country is an important tin resource producing area in the world and has long been a world leader in reserves and production. However, in recent years, due to the difficulty in making breakthroughs in deep and marginal prospecting theories and technologies, the traditional tin mineralization potential is mainly based on geological analysis (ore field structure, geological construction, intrusive bodies, etc.), geophysical anomalies (seismic, electromagnetic methods, etc.), and geochemical anomalies (primary ore halos, secondary ore halos, etc.). The methods are inefficient, difficult, and costly, which greatly limits the exploration of tin resources, making my country's tin resource output insufficient to support the development of related industries, and even requires large-scale reliance on imports.

[0003] Tourmaline is a complex borate mineral widely found in various types of mineral deposits. It has an extremely low intracrystalline element diffusion rate (generally believed to be non-diffusion) and a wide temperature and pressure stability range (temperature is 0-950℃, pressure is 0-5GPa). Once crystallized, its physical and chemical properties remain stable, and tourmaline can accommodate a variety of trace elements through substitution. The distribution coefficient of most trace elements between tourmaline and silicate melt is close to 1. The content of major and trace elements in tourmaline can sensitively reflect the geological environment when tourmaline was formed and record the physical and chemical information of the ore-forming fluid.

[0004] The Sn content of tourmaline records the Sn content during the magma evolution process, which makes it possible to use the tourmaline content to determine the tin mineralization potential at a low cost and high efficiency. However, in fact, some tourmalines that are not related to tin mines may also have a high content of Sn, resulting in the ineffectiveness of using only the tourmaline Sn content to determine the tin mineralization potential, and the accuracy is low.

[0005] Therefore, we urgently need to provide a method to improve the accuracy of identifying tin mineralization potential, which provides a more reliable basis for the investigation and evaluation of tin mineralization potential. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a comprehensive method for distinguishing tin mineralization potential based on tourmaline, which can distinguish tin mineralization potential efficiently, accurately and at low cost.

[0007] The technical solution adopted by the present invention to solve the technical problem is: a comprehensive identification method of tin mineralization potential based on tourmaline, comprising the following steps:

[0008] 1) Field geological survey: Conduct detailed field geological survey in the target area, preliminarily classify tourmaline according to its occurrence, and systematically collect different types of tourmaline after preliminary classification to ensure comprehensive sampling without omissions;

[0009] 2) Microscopic observation: Observe the characteristics of different types of tourmaline under a microscope, record the petrographic characteristics of tourmaline in detail, and further subdivide the types of tourmaline according to the occurrence and petrographic characteristics of tourmaline;

[0010] 3) Geochemical analysis: trace element and major element analysis of all types of tourmaline;

[0011] 4) Preliminary identification of tin mineralization potential: The content of Sn in the trace elements contained in tourmaline is used to preliminarily indicate the tin mineralization potential of the rock body or hydrothermal vein represented by the tourmaline;

[0012] 5) Magma evolution analysis: By analyzing the data of trace element and major element content of tourmaline, combined with the occurrence and petrographic characteristics of tourmaline, the origin and evolution degree of different types of tourmaline are clarified, and the spatial position of each type of tourmaline and the mineralization rock body is found out;

[0013] 6) Final determination of tin mineralization potential: Based on the origin and evolution degree of tourmaline determined in step 5) and the spatial position of each tourmaline and mineralization rock mass, combined with the preliminary determination results of tin mineralization potential in step 4), the tin mineralization potential of the rock mass or hydrothermal vein represented by the tourmaline is finally determined, and the tin mineralization target area is delineated.

[0014] Furthermore, target area selection includes but is not limited to areas with abnormal geophysical or geochemical data, areas with confirmed ore bodies, or coupled areas with obvious ore-controlling structures.

[0015] Furthermore, the occurrence of tourmaline that needs to be ascertained during the field geological survey includes, but is not limited to, four characteristics of the spatial distribution relationship between tourmaline and rock mass, surrounding rock, dykes, and ore minerals.

[0016] Furthermore, the spatial distribution relationship also includes the interlacing relationship between different dykes.

[0017] Furthermore, the specific operation steps of step 2) are: making thin slices of different types of tourmaline that have been preliminarily classified, observing the tourmaline using an optical microscope or an electron microscope, and recording the petrographic characteristics of the tourmaline in detail; if there are ring-band characteristics, backscattered photos can be taken to further observe the ring-band characteristics of the tourmaline and further subdivide the tourmaline types.

[0018] Furthermore, petrographic characteristics include but are not limited to the color of tourmaline, its interpenetration with other minerals, mineral structure, and mineral combination.

[0019] Furthermore, the trace elements in step 3) include Li, Be, Co, Sr and Sn.

[0020] If the test results of the Sn element are missing, it is impossible to make a preliminary judgment on the tin mineralization potential in step 4) based on the content of the Sn element; if one or more trace elements among Li, Be, Co, and Sr are missing, it is impossible to judge the evolution degree of the tourmaline in step 5), and thus it is impossible to optimize the result of the preliminary judgment. It is also impossible to make a final judgment on the tin mineralization potential in step 6). Ultimately, it will be impossible to conduct a comprehensive analysis in the final judgment of the tin mineralization potential in step 6), and thus it is impossible to obtain the final judgment result of the tin mineralization potential.

[0021] Furthermore, the major elements in step 3) include SiO2, TiO2, Al2O3, FeO, MnO, MgO, CaO, Na2O, K2O, F and Cl.

[0022] If the test results of FeO or MgO are missing, it is impossible to determine the spatial position of tourmaline and the mineralized rock mass in step 5); if the test results of any one or several of the major elements are missing, it is also impossible to determine the ideal molecular formula of tourmaline based on XY3Z6(T6O 18 )(BO3)3V3W cannot accurately calculate the Ti content, and thus cannot accurately determine the evolution degree of tourmaline in step 5). This will ultimately lead to the inability to conduct a comprehensive analysis in the final determination of tin mineralization potential in step 6), and thus the inability to obtain the final determination result of tin mineralization potential.

[0023] Furthermore, the specific method for preliminary determination of tin mineralization potential in step 4) is as follows: if the content of the Sn element is less than 100 ppm, it is preliminarily determined that the rock mass or hydrothermal vein represented by the tourmaline does not have tin mineralization potential; if the content of the Sn element is ≥100 ppm, it is preliminarily determined that the rock mass or hydrothermal vein represented by the tourmaline has tin mineralization potential.

[0024] Furthermore, the method for determining the origin of tourmaline in step 5) is as follows: tourmaline with a ring-shaped structure and / or formed in hydrothermal veins is caused by hydrothermal fluids, and other tourmalines are caused by magma.

[0025] Furthermore, the method for determining the evolution degree in step 5) is as follows: as the evolution degree of tourmaline increases, the contents of Li, Be and Sr in the system gradually increase, and the contents of Co and Ti gradually decrease.

[0026] Furthermore, the method for determining the spatial position of tourmaline and the mineralized rock mass in step 5) is as follows: when FeO / (FeO+MgO) of tourmaline is greater than 0.8, it indicates that the tourmaline is located inside the mineralized rock mass or at the proximal end of the mineralized rock mass, wherein the proximal end of the mineralized rock mass means that the distance between the tourmaline and the mineralized rock mass is less than 100 meters; when 0.6≤FeO / (FeO+MgO)≤0.8, it indicates that the distance between the tourmaline and the mineralized rock mass is 100 meters to 1000 meters, and the tourmaline is located at the middle end of the mineralized rock mass; when FeO / (FeO+MgO) of tourmaline is less than 0.6, it indicates that the distance between the tourmaline and the mineralized rock mass is greater than 1000 meters, and the tourmaline is located at the distal end of the mineralized rock mass.

[0027] Further, the specific operation steps of step 6) are: according to the result of the preliminary identification of tin mineralization potential in step 4) and the analysis results of the origin, evolution degree and spatial position of tourmaline and mineralization rock mass obtained in step 5), when the tourmaline satisfies the four indicators that the rock mass or hydrothermal vein represented by it is preliminarily identified as having tin mineralization potential, the origin of the tourmaline is hydrothermal, the evolution degree is high, and it is located in the mineralization rock mass or at the proximal end of the mineralization rock mass, it means that the rock mass or hydrothermal vein represented by the tourmaline has tin mineralization potential, and the area with a radius of less than 100 meters from the tourmaline is delineated as a tin mineralization target area, and the tin mineralization target area has high tin mineralization potential; if the tourmaline does not meet these four indicators at the same time, it means that the rock mass or hydrothermal vein represented by the tourmaline does not have tin mineralization potential.

[0028] Beneficial effects of the comprehensive identification method of tin mineralization potential based on tourmaline of the present invention:

[0029] (1) The present invention provides a comprehensive identification method for tin mineralization potential based on tourmaline, which first obtains the occurrence information of tourmaline on the basis of field geological survey and makes a preliminary classification of types; then obtains the petrographic characteristics of tourmaline through microscopic observation and subdivides the types of tourmaline; then determines the contents of trace elements and major elements in tourmaline and makes a preliminary identification of the tin mineralization potential of the rock or hydrothermal vein represented by the tourmaline based on the content of Sn element; then uses the occurrence and petrographic characteristics of tourmaline and the determination results of major elements and trace elements to identify the tin mineralization potential of tourmaline. The origin, evolution sequence and spatial position of tourmaline with the mineralized rock body are determined; finally, based on the four indicators of preliminary identification of tin mineralization potential, origin of tourmaline, evolution degree and spatial position of tourmaline with the mineralized rock body, it is finally determined whether the rock or hydrothermal vein represented by tourmaline has tin mineralization potential, and the tin mineralization target area is delineated; compared with traditional identification methods - geological analysis (such as ore field structure, geological construction, intrusive body, etc.), geophysical anomalies (seismic, electromagnetic method, etc.) and geochemical anomalies (primary ore halo, secondary ore halo) and other methods, this method can significantly improve exploration efficiency and reduce exploration costs.

[0030] (2) Compared with using only the content of Sn in tourmaline to determine the tin mineralization potential, the present invention also integrates field geological surveys, petrographic characteristics such as tourmaline color and structure, and clarifies the genesis and evolution sequence of tourmaline and its spatial position with the mineralization rock body based on geochemical data, so as to further limit the mineralization potential, improve the accuracy of exploration, solve the problem of difficulty and high cost in prospecting in the deep edge of the ore deposit, and provide a new idea and method for the exploration of tin ore deposits;

[0031] (3) The present invention is an economical, green and efficient new method for prospecting. Through the collection of a large amount of data, it is found that the accuracy of finding tin deposits by this method is greater than 90%. It has high application prospects and market potential, and can provide technical support and decision-making basis for scientific researchers, prospectors and enterprises in related fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 — is a schematic flow diagram of a comprehensive method for distinguishing tin mineralization potential based on tourmaline according to the present invention;

[0033] Figure 2 —are the field, hand specimen, optical microscope and backscattered images of Tur-I tourmaline in Example 1;

[0034] Figure 3 —Field, hand specimens, optical microscope and backscattered images of Tur-II tourmaline in Example 1;

[0035] Figure 4 —Field, hand specimen, optical microscope and backscattered images of Tur-III tourmaline in Example 1;

[0036] Figure 5 —Field, hand specimen, optical microscope and backscattered images of Tur-IV tourmaline in Example 1;

[0037] Figure 6 —Field, hand specimen, optical microscope and backscattered image of Tur-V tourmaline in Example 1;

[0038] Figure 7 — is a trace element box diagram of Tur-I, Tur-III, Tur-III, Tur-IV, and Tur-V in Example 1;

[0039] Figure 8 —are the field, single-piece light and orthogonal mirror images of Tur-I, Tur-II, Tur-III and Tur-IV in Example 2;

[0040] Fig. 9— is the trace element box diagram of Tur-I, Tur-II, Tur-III and Tur-IV in Example 2. DETAILED DESCRIPTION

[0041] The present invention is further described below in conjunction with the accompanying drawings and examples, but these specific implementation schemes do not limit the protection scope of the present invention in any way.

[0042] like Figure 1 As shown, the present invention provides a comprehensive method for distinguishing tin mineralization potential based on tourmaline, which specifically includes the following steps:

[0043] 1) Field geological survey: Based on the geological information that has been explored by predecessors (such as the regional strata, structure, magmatic rocks, ore minerals, mineralization conditions and geological age information), select potential tin mineralization target areas. The target area selection includes but is not limited to: ① areas with abnormal geophysical or geochemical data; ② areas where ore bodies have been identified; ③ coupling areas with obvious ore-controlling structures. Conduct a detailed field geological survey of the target area to determine the spatial distribution relationship between tourmaline and rock bodies (such as granite), surrounding rocks, veins (such as quartz veins or fluorite veins) and ore minerals (such as exposed cassiterite). In this process, special attention is paid to the interlacing relationship between different veins. According to the occurrence of the tourmaline obtained, the tourmaline is preliminarily classified, and fresh and representative tourmaline samples of different types are collected comprehensively and systematically, and ensure that the sampling is comprehensive and without omissions;

[0044] 2) Microscopic observation: Grind fresh and representative tourmaline samples into thin slices, probe slices and laser slices, and observe and identify the tourmaline slices in detail under an optical microscope or electron microscope using single-piece light and orthogonal polarized light respectively. If tourmaline zoning is found under the microscope, take backscattered photos to further observe the zoning characteristics of the tourmaline and record the petrographic characteristics of the tourmaline; further subdivide the types of tourmaline based on the petrographic characteristics of tourmaline, such as color (brightness and color difference), structure (mineral eumorphism, inclusion and interlacing relationship with other minerals, whether there are obvious zoning characteristics), mineral combination (symbiotic relationship with cassiterite), etc.

[0045] 3) Geochemical analysis: Geochemical analysis was conducted on different types of tourmaline samples. The main elements tested included SiO2, TiO2, Al2O3, FeO, MnO, MgO, CaO, Na2O, K2O, F and Cl. The trace elements tested included Li, Be, Co, Sr and Sn.

[0046] 4) Preliminary determination of tin mineralization potential: Based on the determination results of the Sn content in trace elements, if the Sn content is less than 100ppm, it is preliminarily determined that the rock body or hydrothermal vein represented by the tourmaline does not have tin mineralization potential; if the Sn content is ≥100ppm, it is preliminarily determined that the rock body or hydrothermal vein represented by the tourmaline has tin mineralization potential. 5) Analysis of magma evolution: By analyzing the data of the trace element and major element content of tourmaline, combined with the occurrence and petrographic characteristics of tourmaline, the genesis and evolution degree of different types of tourmaline are clarified, and the spatial position of each type of tourmaline and the mineralization rock body is found out; specifically:

[0047] The method for distinguishing the origin of tourmaline is as follows: the method for distinguishing the origin of tourmaline in step 5) is as follows: tourmaline with a ring-shaped structure and / or formed in a hydrothermal vein is caused by hydrothermal fluids and is in the late stage of evolution; other tourmalines are caused by magma and are in the early stage of evolution.

[0048] The method for judging the degree of evolution is: as the degree of evolution of tourmaline increases, the content of Li, Be and Sr in the system gradually increases, and the content of Co and Ti gradually decreases. Tourmaline in the late stage of evolution is enriched in incompatible elements such as Li, Be and Sr, and depleted in Co and Ti elements.

[0049] The method for distinguishing the spatial position of tourmaline and the mineralized rock body is as follows: when the FeO / (FeO+MgO) of tourmaline is greater than 0.8, it indicates that the tourmaline is located in the mineralized rock body or at the proximal end of the mineralized rock body, and the proximal end of the mineralized rock body means that the distance between the tourmaline and the mineralized rock body is less than 100 meters; when 0.6≤FeO / (FeO+MgO)≤0.8, it indicates that the distance between the tourmaline and the mineralized rock body is 100 meters to 1000 meters, and it is located in the middle of the mineralized rock body; when the FeO / (FeO+MgO) of tourmaline is less than 0.6, it indicates that the distance between the tourmaline and the mineralized rock body is greater than 1000 meters, and it is located at the distal end of the mineralized rock body. The spatial position of tourmaline and the mineralized rock body can be used to effectively locate the ore body position of the tin mineralization target area.

[0050] 6) Final determination of tin mineralization potential: According to the results of the preliminary determination of tin mineralization potential in step 4) and the results of the analysis of the origin, evolution degree and spatial position of tourmaline and mineralization rock mass obtained in step 5), when tourmaline satisfies the four indicators that the rock mass or hydrothermal vein represented by it is initially determined to have tin mineralization potential, the origin of tourmaline is hydrothermal, the evolution degree is high, and it is located in the mineralization rock mass or at the proximal end of the mineralization rock mass, it indicates that the rock mass or hydrothermal vein represented by the tourmaline has tin mineralization potential, and the area with a radius of less than 100 meters from the tourmaline is defined as a tin mineralization target area, and the tin mineralization target area has high tin mineralization potential; if tourmaline does not meet these four indicators at the same time, it indicates that the rock or hydrothermal vein represented by the tourmaline does not have tin mineralization potential. The organic combination of the various steps of the present invention is the key to ensure accurate identification of tin mineralization potential. Using one of the steps alone may limit the comprehensive grasp of tin mineralization potential. If we only rely on geochemical analysis without combining the magmatic evolution process, we can only make a preliminary judgment on the tin mineralization potential. In actual application, due to the high Sn content in the basement in some areas, the Sn content in the tourmaline with a low evolution degree and far from the mineralization rock body is ≥100ppm, but no tin ore is found in the tin mineralization target area delineated by the tourmaline. Similarly, if we only analyze the magmatic evolution process of tourmaline, due to the presence of hydrothermal tourmaline (such as hydrothermal tourmaline related to tungsten ore) in the late evolution period close to the mineralization rock body that is unrelated to tin mineralization, this type of tourmaline will affect the judgment of the tin mineralization potential. Therefore, when implementing the method of the present invention, the importance of each step should be fully considered, and they should be organically combined to obtain a more reliable and accurate result of the discrimination of tin mineralization potential.

[0051] Taking Example 1 and Example 2 as examples, the method of the present invention is used to respectively survey the tin mineralization potential of ore deposits in different regions.

[0052] Example 1

[0053] This embodiment takes the Xianghualing tin polymetallic deposit in Linwu County, Chenzhou City, Hunan Province as an example. Previous studies have shown that the deposit has proven SnO2 metal resources of 250,000 tons, intermediate-acidic magmatic rocks are widely developed in the mining area, and a well-developed magmatic hydrothermal mineralization system is developed around granite stocks and veins. Therefore, the deposit meets the condition of being selected as an "area with identified ore bodies" in the target target area, and can be used as a target area for the identification of tin mineralization potential.

[0054] Therefore, for the target area, a comprehensive identification method of tin mineralization potential based on tourmaline of the present invention is adopted, which specifically includes the following operating steps:

[0055] 1) We conducted a detailed field geological survey of the target area and found that a large amount of tourmaline was exposed in the target area. Based on the spatial distribution relationship between tourmaline and rock mass, surrounding rock, dyke and ore minerals, we found that tourmaline was exposed in the granite mass, skarn and quartz sandstone beside the granite mass in the target area. In addition, a large amount of tourmaline was also found in a hydrothermal vein (tourmaline-fluorite vein) developed in skarn. Therefore, we preliminarily divided the types of tourmaline into ① tourmaline in granite; ② tourmaline in skarn; ③ tourmaline in hydrothermal veins; ④ tourmaline in quartz sandstone; comprehensively and systematically collected fresh and representative tourmaline samples of different types, and ensured that the sampling was comprehensive and without omissions;

[0056] 2) Microscopic observation: The tourmaline samples were ground into thin slices, probe slices and laser slices. The thin slices were observed in detail under an optical microscope to record the petrographic characteristics of the tourmaline. The results are as follows:

[0057] Tourmaline (Tur-I) in granite is distributed in rock-forming minerals such as biotite in a disseminated manner and is light blue in color under an orthogonal microscope ( Figure 2 );

[0058] Tourmaline in skarn is divided into tourmaline in inner skarn close to the rock body (Tur-II) according to its distance from the rock body. Figure 3 ) and the outer skarn tourmaline (Tur-III) far from the rock mass ( Figure 4 ); The tourmaline in both the inner and outer skarns has a distinct ring-shaped structure. However, the former is produced in long columnar shapes with hexagonal sections and appears pale yellow under a single polarizing microscope, while the latter is produced in long columnar crystal clusters and appears pale yellow under a single polarizing microscope;

[0059] Tourmaline in hydrothermal veins (Tur-IV) is developed in tourmaline-fluorite veins that cut into skarn. It is a tourmaline formed in hydrothermal veins. Its ring bands are clear and wide, and it appears light blue under a single polarizing microscope ( Figure 5 );

[0060] Tourmaline (Tur-V) in quartz sandstone is produced in cassiterite-sulfide-tourmaline-fluorite veins. It is a tourmaline formed in hydrothermal veins. Tourmaline is radial and yellow-green under a single optical microscope ( Figure 6 );

[0061] 3) Geochemical analysis: Geochemical analysis was conducted on different types of tourmaline samples. The main elements tested included SiO2, TiO2, Al2O3, FeO, MnO, MgO, CaO, Na2O, K2O, F and Cl. The trace elements tested included Li, Be, Co, Sr and Sn.

[0062] 4) Preliminary judgment of tin mineralization potential: According to the determination of the content of trace element Sn by geochemical analysis, the contents of Sn in Tur-I, Tur-II, Tur-III, Tur-IV, and Tur-V are 73ppm, 214ppm, 237ppm, 312ppm, and 323ppm respectively. The average Sn content of Tur-I is less than 100ppm, and it is preliminarily judged that the granite represented by Tur-I does not have tin mineralization potential; the contents of Sn in the other four types of tourmaline (Tur-II, Tur-III, Tur-IV, and Tur-V) are all greater than 100ppm, and it is preliminarily judged that the inner skarn represented by Tur-II, the outer skarn represented by Tur-III, the hydrothermal vein represented by Tur-IV, and the quartz sandstone represented by Tur-V all have tin mineralization potential;

[0063] 5) Analysis of magma evolution:

[0064] Identification of the origin of tourmaline: Tur-I does not have zoning characteristics and does not belong to the tourmaline formed in hydrothermal veins. It is determined that this type of tourmaline is of early magmatic origin; Tur-II, Tur-III and Tur-IV all have obvious zoning characteristics, and Tur-IV and Tur-V are all formed in hydrothermal veins. It is determined that Tur-II, Tur-III, Tur-IV and Tur-V are all derived from hydrothermal fluids and are formed later than Tur-I.

[0065] Determination of the degree of evolution: Figure 7 It can be seen that the Sr content corresponding to the magmatic Tur-I is the lowest, and the ore-forming element Sr is an incompatible element, which usually enters the fluid that evolves to the late stage. Therefore, the mineralization potential of Tur-I is the smallest, which further verifies the result that Tur-I obtained in step 4) does not have the potential for tin mineralization;

[0066] Compared with the magmatic Tur-I, Tur-II, Tur-III, Tur-IV and Tur-V all have higher contents of Li, Be and Sr, and lower contents of Co and Ti. The contents of Li, Be and Sr corresponding to Tur-II, Tur-III, Tur-IV and Tur-V all show a trend of increasing gradually; the contents of Co and Ti corresponding to Tur-II, Tur-III, Tur-IV and Tur-V all show a trend of decreasing gradually, indicating that the evolution degree of tourmaline gradually increases from Tur-I to Tur-V.

[0067] Discrimination of the spatial position of tourmaline and mineralized rock bodies: According to the determination of the contents of the major elements FeO and MgO by geochemical analysis, the ratio of FeO / (FeO+MgO) in tourmaline was calculated. The results are as follows: the ratios of FeO / (FeO+MgO) in Tur-I, Tur-II, Tur-III, Tur-IV and Tur-V are 0.98, 0.91, 0.74, 0.64 and 0.95 respectively, among which the ratios of FeO / (FeO+MgO) in Tur-I, Tur-II, Tur-III, Tur-IV and Tur-V are 0.98, 0.91, 0.74, 0.64 and 0.95 respectively. The FeO / (FeO+MgO) corresponding to Tur-II and Tur-V is greater than 0.8, indicating that Tur-I, Tur-II and Tur-V are located in the ore-forming rock mass or near the ore-forming rock mass, and the distance from the ore-forming rock mass is less than 100 meters; the FeO / (FeO+MgO) corresponding to Tur-III and Tur-IV is between 0.6 and 0.8, indicating that Tur-III and Tur-IV are located in the middle of the ore-forming rock mass, and the distance from the ore-forming rock mass is 100-1000 meters;

[0068] 6) Final judgment of tin mineralization potential: According to the results of the preliminary judgment of tin mineralization potential in step 4) (the granite represented by Tur-I has no tin mineralization potential, the inner skarn represented by Tur-II, the outer skarn represented by Tur-III, the hydrothermal vein represented by Tur-IV, and the quartz sandstone represented by Tur-V all have tin mineralization potential) and the origin of tourmaline obtained in step 5) (Tur-I is derived from hydrothermal fluids, Tur-II, Tur-III, Tur-IV and Tur-V are all derived from hydrothermal fluids), the degree of evolution (from low to high: Tur-I, Tur-II, Tur-III, Tur-IV, Tur-V) -V) and the spatial position of tourmaline and mineralization rock body (Tur-I, Tur-II, Tur-V are located in the mineralization rock body or at the proximal end of the mineralization rock body, and Tur-III and Tur-IV are located in the middle end of the mineralization rock body) analysis results show that Tur-V meets the four indicators that the quartz sandstone it represents is initially judged to have tin mineralization potential, is hydrothermal in origin, has a high degree of evolution, and is located in the mineralization rock body or at the proximal end of the mineralization rock body. This shows that the quartz sandstone represented by tourmaline Tur-V has tin mineralization potential, and the area with a radius of less than 100 meters from tourmaline Tur-V is a tin mineralization target area, which has high tin mineralization potential. After later verification, a Paojinshan-like layered tin ore body (a stockwork-type ore body with quartz sandstone as the host rock) was found near tourmaline Tur-V (about 50m away).

[0069] Example 2

[0070] This embodiment takes the Wangxianling area in Suxian District, Chenzhou City, Hunan Province, where a large number of tungsten-tin polymetallic deposits are developed, as an example. Previous studies have shown that the proven tin resource reserves of the deposit exceed 190,000 tons and the tungsten resource reserves exceed 110,000 tons, and it has good mineralization potential. Therefore, the deposit meets the condition of being selected as the "area with identified ore bodies" in the target area, and can be used as a target area for the identification of tin mineralization potential.

[0071] Therefore, for the target area, a comprehensive identification method of tin mineralization potential based on tourmaline of the present invention is adopted, which specifically includes the following operating steps:

[0072] 1) A detailed field geological survey of the target area was conducted, and it was found that a large amount of tourmaline was exposed in the target area. Based on the spatial distribution relationship between tourmaline and rock mass, surrounding rock, rock veins and ore minerals, we found that tourmaline was exposed in the two-mica granite and biotite granite in the target area. In addition, tourmaline was also found in the hydrothermal veins in the two types of granite, but not in the surrounding rock or around ore minerals such as cassiterite and scheelite. Therefore, we preliminarily divided the types of tourmaline into ① tourmaline in two-mica granite; ② tourmaline in biotite granite; ③ tourmaline in hydrothermal veins; comprehensively and systematically collected different types of fresh and representative tourmaline samples, and ensured that the sampling was comprehensive and without omissions;

[0073] 2) Microscopic observation: Grind the sampled tourmaline into thin slices, probe slices and laser slices, observe the thin slices in detail under an optical microscope, and record the petrographic characteristics of tourmaline (such as Figure 8 According to petrographic characteristics, it can be divided into the following four categories:

[0074] ① Tourmaline (Tur-I) is distributed in two-mica granite in a disseminated manner. This type of tourmaline is euhedral granular or short columnar, and coexists with rock-forming minerals such as quartz, feldspar, and mica. The ring zoning feature is not obvious, and it appears light yellow to light brown under an orthogonal microscope;

[0075] ② Tourmaline (Tur-II) is distributed in the biotite granite in a disseminated manner. This type of tourmaline has a low content and is dispersed in the form of long columnar single particles. It is yellow-brown in color under an orthogonal microscope, with uniform composition and no obvious zoning.

[0076] ③Tourmaline (Tur-III) in the quartz veins that cut through the two-mica granite. This type of tourmaline is mostly euhedral fine-grained and needle-shaped under the microscope, with no obvious zoning characteristics, and is light blue under the orthogonal microscope;

[0077] ④ Tourmaline (Tur-IV) in quartz veins that cut through biotite granite. This type of tourmaline has a good degree of crystallization, a particle size of 0.2-1mm, and is euhedral / semi-euhedral long columnar or forms radioactive aggregates that coexist with quartz (fluorite can be seen locally). The cross section is hexagonal and the ring zoning characteristics are not obvious;

[0078] 3) Geochemical analysis: Geochemical analysis was conducted on different types of tourmaline samples. The main elements tested included SiO2, TiO2, Al2O3, FeO, MnO, MgO, CaO, Na2O, K2O, F and Cl. The trace elements tested included Li, Be, Co, Sr and Sn.

[0079] 4) Preliminary determination of tin mineralization potential: According to the determination of the content of trace element Sn by geochemical analysis, the contents of Sn in Tur-I, Tur-II, Tur-III and Tur-IV are 29ppm, 34ppm, 38ppm and 115ppm respectively. Only the content of Sn in Tur-IV is greater than 100ppm, and it is preliminarily determined that the quartz veins cut through biotite granite represented by Tur-IV have tin mineralization potential; the contents of Sn in the other three types of tourmaline (Tur-I, Tur-II and Tur-III) are all less than 100ppm, and it is preliminarily determined that the two-mica granite represented by Tur-I, the biotite granite represented by Tur-II and the quartz veins cut through two-mica granite represented by Tur-III do not have tin mineralization potential. However, further analysis of the magmatic evolution process is still needed to further determine whether the quartz veins cut through the biotite granite represented by Tur-IV have tin mineralization potential and to delineate the tin mineralization target area;

[0080] 5) Analysis of magma evolution:

[0081] Identification of the origin of tourmaline: Tur-I and Tur-II do not have zoning characteristics and do not belong to tourmaline formed in hydrothermal veins. It is determined that these two types of tourmaline are early magmatic tourmaline; although Tur-III and Tur-IV do not have zoning characteristics, they are produced in quartz veins and are tourmaline formed in hydrothermal veins. It is determined that Tur-III and Tur-IV are both derived from hydrothermal fluids and were formed later than Tur-I and Tur-II.

[0082] Determination of the degree of evolution: Fig. 9 It can be seen that the contents of Li, Be, and Sr from Tur-I to Tur-IV all show a trend of gradual increase, while the contents of Co and Ti elements all show a trend of gradual decrease, which indicates that the evolution degree of tourmaline gradually increases from Tur-I to Tur-IV.

[0083] Discrimination of the spatial position of tourmaline and mineralization rock body: According to the determination of the content of the major elements FeO and MgO by geochemical analysis, the ratio of FeO / (FeO+MgO) in tourmaline was calculated. The results are as follows: the ratios of FeO / (FeO+MgO) in Tur-I, Tur-II, Tur-III and Tur-IV are 0.68, 0.72, 0.77 and 0.98 respectively, among which the FeO / (FeO+MgO) corresponding to Tur-IV is>0.8, indicating that Tur-IV is located in the mineralization rock body or at the near end of the mineralization rock body, and the distance from the mineralization rock body is less than 100 meters; the FeO / (FeO+MgO) corresponding to the other three types of tourmaline (Tur-I, Tur-II, Tur-III) is 0.6-0.8, indicating that Tur-I, Tur-II and Tur-III are all located in the middle end of the mineralization rock body, and the distance from the mineralization rock body is 100-1000 meters;

[0084] 6) Final judgment of tin mineralization potential: According to the results of the preliminary judgment of tin mineralization potential in step 4) (the two-mica granite represented by Tur-I, the biotite granite represented by Tur-II, and the quartz vein cutting through the two-mica granite represented by Tur-III do not have tin mineralization potential, and the quartz vein cutting through the biotite granite represented by Tur-IV has tin mineralization potential) and the origin of tourmaline obtained in step 5) (Tur-I and Tur-II are derived from magma; Tur-III and Tur-IV are derived from tourmaline in hydrothermal veins, and it is determined that Tur-III and Tur-IV are both derived from hydrothermal fluids), evolution degree (from low to high: Tur-I, Tur-II, Tur-III The results of the analysis of the spatial positions of tourmaline and mineralization rock bodies (Tur-IV is located in the mineralization rock body or at the proximal end of the mineralization rock body, and Tur-I, Tur-II and Tur-III are located in the middle end of the mineralization rock body) show that Tur-IV satisfies the four indicators that the quartz veins that cut through the biotite granite represented by it are initially judged to have tin mineralization potential, are hydrothermal in origin, have a high degree of evolution, and are located in the mineralization rock body or at the proximal end of the mineralization rock body. This indicates that the quartz veins that cut through the biotite granite represented by tourmaline Tur-IV have tin mineralization potential, and the area with a radius of less than 100 meters from tourmaline Tur-IV is a tin mineralization target area, which has high tin mineralization potential. After later verification, the Hehuaping cassiterite sulfide tin ore body was discovered near tourmaline Tur-IV (about 20m away).

[0085] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A comprehensive method for distinguishing tin mineralization potential based on tourmaline, characterized in that: The following steps are involved: 1) Field geological survey: Conduct detailed field geological survey in the target area, preliminarily classify tourmaline according to its occurrence, and systematically collect different types of tourmaline after preliminary classification to ensure comprehensive sampling without omissions; 2) Microscopic observation: Observe the characteristics of different types of tourmaline under a microscope, record the petrographic characteristics of tourmaline in detail, and further subdivide the types of tourmaline according to the occurrence and petrographic characteristics of tourmaline; 3) Geochemical analysis: All types of tourmaline are analyzed for trace elements and major elements; the trace elements in step 3) include Li, Be, Co, Sr and Sn, and the major elements include SiO2, TiO2, Al2O3, FeO, MnO, MgO, CaO, Na2O, K2O, F and Cl; 4) Preliminary identification of tin mineralization potential: The content of Sn in the trace elements contained in tourmaline is used to preliminarily indicate the tin mineralization potential of the rock body or hydrothermal vein represented by the tourmaline; 5) Magma evolution analysis: By analyzing the data of trace element and major element content of tourmaline, combined with the occurrence and petrographic characteristics of tourmaline, the origin and evolution degree of different types of tourmaline are clarified, and the spatial position of each type of tourmaline and the mineralization rock body is found out; 6) Final determination of tin mineralization potential: Based on the origin and evolution degree of tourmaline determined in step 5) and the spatial position of each tourmaline and the mineralization rock mass, combined with the preliminary determination results of tin mineralization potential in step 4), the tin mineralization potential of the rock mass or hydrothermal vein represented by the tourmaline is finally determined, and the tin mineralization target area is delineated; the specific operation steps are: according to the results of the preliminary determination of tin mineralization potential in step 4) and the analysis results of the origin, evolution degree and spatial position of tourmaline and the mineralization rock mass obtained in step 5), when the tourmaline meets both the requirements If the rock mass or hydrothermal vein represented by the tourmaline is preliminarily judged to have tin mineralization potential, the tourmaline is hydrothermal in origin, has a high degree of evolution, and is located within or near the mineralization rock mass, then it means that the rock mass or hydrothermal vein represented by the tourmaline has tin mineralization potential, and the area with a radius of less than 100 meters from the tourmaline is identified as a tin mineralization target area, which has high tin mineralization potential. If the tourmaline does not meet these four indicators at the same time, then it means that the rock mass or hydrothermal vein represented by the tourmaline does not have tin mineralization potential.

2. A comprehensive identification method of tin mineralization potential based on tourmaline as claimed in claim 1, characterized in that: The occurrence of tourmaline that needs to be ascertained during the field geological survey includes, but is not limited to, the spatial distribution relationship between tourmaline and rock mass, surrounding rock, dykes, and ore minerals.

3. A comprehensive determination method of tin mineralization potential based on tourmaline as claimed in claim 1, characterized in that: The specific operation steps of step 2) are: making thin slices of different types of tourmaline that have been initially classified, observing the tourmaline using an optical microscope or an electron microscope, and recording the petrographic characteristics of the tourmaline in detail; if there are ring-band characteristics, backscattered photos can be taken to further observe the ring-band characteristics of the tourmaline and further subdivide the types of tourmaline.

4. A comprehensive determination method of tin mineralization potential based on tourmaline as claimed in claim 1, characterized in that: The specific method for the preliminary determination of tin mineralization potential in step 4) is as follows: if the content of the Sn element is less than 100 ppm, it is preliminarily determined that the rock mass or hydrothermal vein represented by the tourmaline does not have tin mineralization potential; if the content of the Sn element is ≥100 ppm, it is preliminarily determined that the rock mass or hydrothermal vein represented by the tourmaline has tin mineralization potential.

5. A comprehensive determination method of tin mineralization potential based on tourmaline as claimed in claim 1, characterized in that: The method for determining the origin of the tourmaline in step 5) is as follows: tourmaline with a ring-shaped structure and / or formed in a hydrothermal vein is caused by hydrothermal fluid, and other tourmalines are caused by magma.

6. A comprehensive determination method of tin mineralization potential based on tourmaline as claimed in claim 1, characterized in that: The method for judging the evolution degree in step 5) is as follows: as the evolution degree of tourmaline increases, the contents of Li, Be and Sr in the system gradually increase, and the contents of Co and Ti gradually decrease.

7. A comprehensive method for distinguishing tin mineralization potential based on tourmaline as claimed in claim 1, characterized in that: The method for determining the spatial position of tourmaline and the mineralized rock mass in the step 5) is as follows: when FeO / (FeO+MgO) of tourmaline is greater than 0.8, it indicates that the tourmaline is located within the mineralized rock mass or at the proximal end of the mineralized rock mass, wherein the proximal end of the mineralized rock mass means that the distance between the tourmaline and the mineralized rock mass is less than 100 meters; when 0.6≤FeO / (FeO+MgO)≤0.8, it indicates that the distance between the tourmaline and the mineralized rock mass is 100 meters to 1000 meters, and the tourmaline is located at the middle end of the mineralized rock mass; when FeO / (FeO+MgO) of tourmaline is less than 0.6, it indicates that the distance between the tourmaline and the mineralized rock mass is greater than 1000 meters, and the tourmaline is located at the distal end of the mineralized rock mass.

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