A method for prospecting and predicting MVT lead-zinc ore deposit

Abstract

The present application relates to a kind of MVT lead-zinc deposit prospecting method, belong to resource exploration technical field.The present application observes MVT lead-zinc deposit host dolomite region, identifies the different alteration zoning of host dolomite, obtains the alteration zoning pattern diagram of dolomite;Collect the dolomite sample of different zoning of host dolomite, prepare different alteration zoning dolomite probe piece sample;Different alteration zoning dolomite probe piece sample is observed to obtain the single polarizing microscope feature map of dolomite, the cathodoluminescence microscope feature map of different alteration zoning of dolomite and the grain size statistical histogram of different alteration zoning dolomite;According to the single polarizing microscope feature map of dolomite, the cathodoluminescence microscope feature map of dolomite and the grain size statistical histogram of different alteration zoning dolomite, the position of ore body in MVT lead-zinc deposit is predicted.The present application establishes the quantitative relationship between the macro-microscopic feature difference variation of MVT lead-zinc deposit host dolomite and lead-zinc mineralization, and realizes prospecting positioning prediction by difference variation.

Description

Technical Field

[0001] This invention relates to a method for predicting the prospecting of MVT lead-zinc deposits, belonging to the field of resource exploration technology. Background Technology

[0002] The MVT lead-zinc deposits, hosted in carbonate rocks, contribute more than 16% of global lead-zinc resources and are generally accompanied by critical metals (In, Ga, Ge, Cd, etc.). Compared to limestone, dolomite is the main host rock in MVT lead-zinc deposits. Dolomitization is the main alteration type in MVT lead-zinc deposits and records fluid information of the corresponding mineralization stages. Dolomite plays a crucial role in the entire MVT lead-zinc deposit mineralization process, manifested in the following ways: 1) Before the precipitation of metal sulfides, water / rock interaction occurs between dolomite and ore-forming fluids, forming large-scale dolomitization, which prepares the necessary lithological, material, and spatial conditions for mineralization; 2) During the precipitation of metal sulfides, the dolomite dissolution-recrystallization (CO2 degassing) cycle buffers the changes in the mineralization environment (such as pH) caused by the large-scale precipitation of metal sulfides, promoting the precipitation and emplacement of dense massive ore bodies and forming a large number of snowflake-shaped (dolomite / calcite spots) characteristic ores; 3) After the precipitation of metal sulfides, carbonate minerals fill and cement the mineralization sites, which is conducive to ore preservation and also becomes an important indicator mineral for prospecting. Because the alteration range of dolomite is much larger than the ore body, it is extremely difficult to use dolomitization as an alteration feature for MVT deposit prospecting and prediction. This technical bottleneck limits the further application of dolomite in MVT deposit prospecting and prediction.

[0003] In existing literature, the steps of using carbonate minerals as key mineral prospecting markers to locate carbonate-type lead-zinc deposits include: Step 1, field screening, classifying carbonate minerals (rocks) developed on the deposit surface and in tunnels according to macroscopic characteristics, systematically collecting (quasi-)syngenetic dolomite, burial-stage dolomite, and hydrothermal dolomite according to their distribution, marking the coordinates of sampling points and taking photos; Step 2, indoor screening, performing cathodoluminescence observation on the obtained carbonate mineral samples to identify carbons with concentric brown-red and dark red cathodoluminescence bands. Step 3: Identify rare earth element geochemical indicators: Perform solution-based or LA-ICPMS in-situ rare earth element geochemical analysis on the key mineral exploration indicator carbonate minerals to obtain rare earth element composition data, and construct a chondrite-normalized distribution diagram of rare earth elements to determine rare earth element index parameters; Step 4: Identify carbon-oxygen-strontium isotope geochemical indicators: Perform carbon-oxygen-strontium isotope composition analysis on the key mineral exploration indicator carbonate minerals to obtain δ¹⁸O₂O₃ ... 13 C、δ 18 O and 87 Sr / 86Step 5 involves determining the Sr value to establish carbon-oxygen-strontium isotope parameters, and then establishing a mineral exploration geochemical index system and drawing anomaly maps to guide mineral exploration. However, the literature requires rare earth element geochemical analysis of carbonate minerals from the macroscopic scale in the field to the microscopic scale in laboratory experiments, as well as the determination of rare earth element index parameters using chondrite-normalized distribution diagrams. This necessitates mineral exploration based on carbon-oxygen-strontium isotope parameters, making the process cumbersome and the analysis difficult. Summary of the Invention

[0004] To address the challenges of using dolomite in MVT (Metal-Oxide-Zinc) deposit prospecting and prediction, this invention proposes a method for MVT lead-zinc deposit prospecting and prediction. This method is based on field dolomitic geological mapping, polarized light microscopy of dolomite, and cathodoluminescence growth zoning observation. Using dolomite as the main host rock in MVT lead-zinc deposits, the macroscopic zoning characteristics of dolomite and ore bodies are identified through field dolomitic geological mapping of the relationship between the host dolomite and the ore body. Typical specimens from each lithofacies zone are selected and ground into probe slides for transmission light microscopy to observe the dolomite structure and grain size, and cathodoluminescence is used to observe the dolomite growth zoning. Quantitative statistics are performed on the dolomite grain size in different zones of the host dolomite. Based on the macroscopic and microscopic characteristics of the host dolomite, the relationship between the host dolomite and the mineralization of the MVT lead-zinc deposit is established, and prospecting prediction is performed through changes in the color, structure, grain size, and cathodoluminescence growth zoning of the host dolomite.

[0005] A prospecting and prediction method for MVT lead-zinc deposits, the specific steps of which are as follows:

[0006] (1) Observe the host dolomite area of ​​the MVT lead-zinc deposit, identify the different alteration zones of the host dolomite, and obtain the alteration zoning pattern diagram of the dolomite; among them, the alteration zones of the host dolomite from the far end to the near end are, in order, dark gray medium-crystalline dolomite zone, gray medium-coarse-crystalline dolomite zone, and light gray-grayish-white coarse-coarse-crystalline dolomite zone.

[0007] (2) Collect dolomite samples from different alteration zones, grind them into probe slides, and obtain dolomite probe slide samples from different alteration zones; avoid weathering and contamination affecting the observation of the slides of the dolomite samples;

[0008] (3) Single polarized light microscopy was used to observe the dolomite probe samples with different alteration zones to identify the changes in dolomite structure from nonplaner→planer-e→planer-s from the far ore end to the near ore end, and the characteristic map of dolomite under single polarized light was obtained.

[0009] (4) Cathodic emission microscopy was used to observe the dolomite probe samples with different alteration zones to identify the five growth zones of the ore-hosting dolomite and obtain the cathodic emission microscopy characteristic images of dolomite with different alteration zones.

[0010] (5) Using Nano Measurer 1.2 software, quantitative particle size statistical analysis was performed on the microscopic feature images of dolomite probe specimens with different alteration zones to obtain the particle size statistical histogram of dolomite with different alteration zones.

[0011] (6) Based on the single polarizing microscope characteristic map of dolomite, the cathodoluminescence microscope characteristic map of dolomite, and the grain size statistical histogram of dolomite in different alteration zones, predict the location of the ore body in the MVT lead-zinc deposit.

[0012] In step (4), the vacuum level observed by the cathodoluminescence microscope is 0.3-0.4 Pa, the beam voltage is 11-12 KV, the beam current is 300-305 μA, the spot diameter is 10-10.5 mm, the gun type is a cold cathode, and the atmosphere is a vacuum.

[0013] In step (4), the growth zones of the ore-bearing dolomite from the far end to the near end are, in sequence, bright red Zone 1, dark red Zone 2, dark red Zone 3, medium bright red Zone 4, and bright red Zone 5.

[0014] The method for predicting the location of the ore body in the MVT lead-zinc deposit in step (6) is as follows:

[0015] 1) The structure of dolomite at the far end, the middle region and the near end was analyzed by the single polarizing microscope. The dolomite at the far end has a nonplaner structure, the dolomite in the middle region has a planer-e structure and the dolomite at the near end has a planer-s structure.

[0016] 2) The cathodoluminescence characteristics of dolomite in different alteration zones were analyzed to determine the luminescence color and thickness of dolomite in the far-ore end, the middle region, and the near-ore end. The far-ore end dolomite mainly developed bright red Zone 1 and dark red Zone 2, with a thickness of 20-200 μm; the middle region dolomite mainly developed dark red Zone 3 and very thin medium-bright red Zone 4 and bright red Zone 5, with a thickness of 7-10 μm; the near-ore end dolomite developed dark red Zone 3, medium-bright red Zone 4, and bright red Zone 5, with a thickness of 150-160 μm.

[0017] 3) The proportion of coarse to very coarse-grained dolomite in the dolomite at the far end of the ore deposit, the dolomite in the middle area, and the dolomite at the near end of the ore deposit was analyzed by the histogram of grain size of dolomite in different alteration zones. The proportion of coarse to very coarse-grained dolomite was 13-26%, and the proportion of coarse to very coarse-grained dolomite in the dolomite in the middle area and near end of the ore deposit was 52-81%.

[0018] 4) The area of ​​light gray to grayish-white coarse to very coarse crystalline dolomite belt with a coarse to very coarse crystalline dolomite content of not less than 52% and dolomite with a planer-s structure and a bright red Zone 5 with a thickness of 150-160μm is the location of the ore body in the adjacent MVT lead-zinc deposit.

[0019] The beneficial effects of this invention are:

[0020] (1) This invention links the trends of dolomite color, structure, grain size, and cathodic luminescence growth zoning with the distance from the ore body to the mineralization of the MVT lead-zinc deposit. Based on the response of the macro- and micro-scale characteristics of dolomite at different locations from the ore body to the ore-forming fluid, the relationship between the trends of dolomite color, structure, grain size, and cathodic luminescence growth zoning with the distance from the ore body and the ore body of the MVT lead-zinc deposit is established.

[0021] (2) This invention combines field and indoor observation results to quickly and accurately identify the characteristics of color, structure, grain size and cathodic luminescence rings of dolomite at different locations away from the ore body, clarify the strength and weakness of the response characteristics of dolomite to ore-forming fluids, reflect the mineralization process, and make mineral exploration predictions through the changes in color, grain size and cathodic luminescence rings of dolomite. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the alteration zoning of ore body (group) I in a certain lead-zinc deposit;

[0023] Figure 2 Microscopic image of the host dolomite of ore body (group) I in a certain lead-zinc deposit;

[0024] Figure 3 A histogram of dolomite grain size in the host dolomite of ore body I (group) of a certain lead-zinc deposit;

[0025] Figure 4 This is a cathodic emission image of dolomite in ore body I (group) of a lead-zinc deposit. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0027] Overview of the Invention

[0028] A prospecting and prediction method for MVT lead-zinc deposits, the specific steps of which are as follows:

[0029] (1) Observe the host dolomite area of ​​the MVT lead-zinc deposit, identify the different alteration zones of the host dolomite, and obtain the alteration zoning pattern diagram of the dolomite; among them, the alteration zones of the host dolomite from the far end to the near end are, in order, dark gray medium-crystalline dolomite zone, gray medium-coarse-crystalline dolomite zone, and light gray-grayish-white coarse-coarse-crystalline dolomite zone.

[0030] (2) Collect dolomite samples from different alteration zones, grind them into probe slides, and obtain dolomite probe slide samples from different alteration zones; avoid weathering and contamination affecting the observation of the slides of the dolomite samples;

[0031] (3) Single polarized light microscopy was used to observe the dolomite probe samples with different alteration zones to identify the changes in dolomite structure from nonplaner→planer-e→planer-s from the far ore end to the near ore end, and the characteristic map of dolomite under single polarized light was obtained.

[0032] (4) Cathodoluminescence microscopy was used to observe the dolomite probe samples with different alteration zones to identify five growth zones of the host dolomite and obtain cathodoluminescence microscopic feature images of dolomite with different alteration zones. The vacuum degree of the cathodoluminescence microscopy was 0.3-0.4 Pa, the beam voltage was 11-12 KV, the beam current was 300-305 μA, the spot diameter was 10-10.5 mm, the gun type was a cold cathode, and the atmosphere was a vacuum. The growth zones of the host dolomite from the far end to the near end of the ore were, in order, bright red Zone 1, dark red Zone 2, dark red Zone 3, medium bright red Zone 4, and bright red Zone 5.

[0033] (5) Using Nano Measurer 1.2 software, quantitative particle size statistical analysis was performed on the microscopic feature images of dolomite probe specimens with different alteration zones to obtain the particle size statistical histogram of dolomite with different alteration zones.

[0034] (6) Based on the single polarizing microscope characteristic map of dolomite, the cathodoluminescence microscope characteristic map of dolomite, and the grain size statistical histogram of dolomite in different alteration zones, predict the location of the ore body in the MVT lead-zinc deposit.

[0035] The method for predicting the location of ore bodies in the MVT lead-zinc deposit is as follows:

[0036] 1) The structure of dolomite at the far end, the middle region and the near end was analyzed by the single polarizing microscope. The dolomite at the far end has a nonplaner structure, the dolomite in the middle region has a planer-e structure and the dolomite at the near end has a planer-s structure.

[0037] 2) The cathodoluminescence characteristics of dolomite in different alteration zones were analyzed to determine the luminescence color and thickness of dolomite in the far-ore end, the middle region, and the near-ore end. The far-ore end dolomite mainly developed bright red Zone 1 and dark red Zone 2, with a thickness of 20-200 μm; the middle region dolomite mainly developed dark red Zone 3 and very thin medium-bright red Zone 4 and bright red Zone 5, with a thickness of 7-10 μm; the near-ore end dolomite developed dark red Zone 3, medium-bright red Zone 4, and bright red Zone 5, with a thickness of 150-160 μm.

[0038] 3) The proportion of coarse to very coarse-grained dolomite in the dolomite at the far end of the ore deposit, the dolomite in the middle area, and the dolomite at the near end of the ore deposit was analyzed by the histogram of grain size of dolomite in different alteration zones. The proportion of coarse to very coarse-grained dolomite was 13-26%, and the proportion of coarse to very coarse-grained dolomite in the dolomite in the middle area and near end of the ore deposit was 52-81%.

[0039] 4) The area of ​​light gray to grayish-white coarse to very coarse crystalline dolomite belt with a coarse to very coarse crystalline dolomite content of not less than 52% and dolomite with a planer-s structure and a bright red Zone 5 with a thickness of 150-160μm is the location of the ore body in the adjacent MVT lead-zinc deposit.

[0040] Example 1: This example uses the 683m, 610m, and 439m sections of the Upper Devonian Zaige Formation in a lead-zinc deposit in northeastern Yunnan as an example. This deposit is located in the north-central part of the eastern Yunnan depression zone on the southwestern margin of the Yangtze Platform. The bedrock of the Upper Devonian Zaige Formation is dolomite, and most of the lead-zinc ore bodies are hosted within it. For this deposit, prospecting and prediction have not yet been conducted from the perspective of the dolomite surrounding rocks. This example utilizes the MVT lead-zinc deposit prospecting and prediction method to conduct field dolomitization mapping, polarized light microscopy, and cathodoluminescence microscopy observations on carbonate rock samples from this deposit. The obtained data and images are analyzed and compared to compare the color, structure, grain size, and cathodoluminescence zoning differences of the dolomite, thereby achieving MVT lead-zinc deposit prospecting and prediction.

[0041] A prospecting and prediction method for MVT lead-zinc deposits, the specific steps of which are as follows:

[0042] (1) Observe the host dolomite area of ​​a lead-zinc deposit in northeastern Yunnan, identify the different alteration zones of the host dolomite, and obtain the alteration zoning pattern diagram of the dolomite (see Figure 1 The alteration zones of the host dolomite, from the far ore end to the near ore end, are successively dark gray medium-crystalline dolomite zone, gray medium- to coarse-crystalline dolomite zone, and light gray to grayish-white coarse- to very coarse-crystalline dolomite zone.

[0043] (2) Collect dolomite samples from three different alteration zones (dark gray medium-gray dolomite zone, gray medium- to coarse-gray dolomite zone, and light gray to grayish-white coarse to very coarse-gray dolomite zone from the far end to the near end of the ore deposit), grind them into probe sections, and obtain dolomite probe section samples of different alteration zones; select fresh dolomite samples to avoid the influence of weathering and contamination on the slice observation; select dolomite area block samples for dolomite probe section samples to avoid areas where other minerals are developed;

[0044] (3) Single-polarized light microscopy was used to observe dolomite probe samples from three different alteration zones (dark gray medium-crystalline dolomite zone, gray medium- to coarse-crystalline dolomite zone, and light gray to grayish-white coarse- to very coarse-crystalline dolomite zone from the far ore end to the near ore end). The change in dolomite structure from nonplaner to planer-e to planer-s was identified from the far ore end to the near ore end. The characteristic images of dolomite under single-polarized light microscopy were obtained (see...). Figure 2 (a and b are seen at the far end of the ore deposit, c and d are seen in the middle area, and e and f are seen at the near end of the ore deposit);

[0045] (4) Cathodoluminescence microscopy was used to observe dolomite probe samples from three different alteration zones (the dark gray medium-gray dolomite zone, the gray medium- to coarse-grained dolomite zone, and the light gray to grayish-white coarse- to very coarse-grained dolomite zone from the far ore end to the near ore end) to identify five growth zones of the host dolomite (see Figure 4 The dolomite exhibits five growth zones (zones 1-5) from the far ore end (a and b), zone 2-3 in the middle region (c and d), and zone 4-5 near the ore end (e and f). These zones are described as bright red (Zone 1), dark red (Zone 2), dark red (Zone 3), medium bright red (Zone 4), and bright red (Zone 5). Cathodoluminescence microscopy was used to obtain cathodoluminescence microscopic images of dolomite with different alteration zones. The vacuum level for the cathodoluminescence microscope observation was 0.3–0.4 Pa, the beam voltage was 11–12 KV, the beam current was 300–305 μA, the spot diameter was 10–10.5 mm, the cathode was cold, and the atmosphere was vacuum. The growth zones of the host dolomite from the far ore end to the near ore end are, in sequence, bright red (Zone 1), dark red (Zone 2), dark red (Zone 3), medium bright red (Zone 4), and bright red (Zone 5).

[0046] (5) Using Nano Measurer 1.2 software, quantitative grain size statistical analysis was performed on the microscopic feature images of dolomite probe samples from three different alteration zones (dark gray medium-crystalline dolomite zone, gray medium- to coarse-crystalline dolomite zone, and light gray to grayish-white coarse- to very coarse-crystalline dolomite zone from the far ore end to the near ore end). Grain size statistical histograms of dolomite from different alteration zones were obtained (see...). Figure 3 ), where AC is seen at the far end of the ore deposit, DF is seen in the middle area, and G and H are seen at the near end of the ore deposit;

[0047] (6) Based on the single polarizing microscope characteristic map of dolomite, the cathodoluminescence microscope characteristic map of dolomite, and the grain size statistical histogram of dolomite in different alteration zones, predict the location of the ore body in the MVT lead-zinc deposit.

[0048] The method for predicting the location of ore bodies in the MVT lead-zinc deposit is as follows:

[0049] 1) The structure of dolomite at the far end, the middle region and the near end was analyzed by the single polarizing microscope. The dolomite at the far end has a nonplaner structure, the dolomite in the middle region has a planer-e structure and the dolomite at the near end has a planer-s structure.

[0050] 2) The cathodoluminescence characteristics of dolomite in different alteration zones were analyzed to determine the luminescence color and thickness of dolomite in the far-ore end, the middle region, and the near-ore end. The far-ore end dolomite mainly developed bright red Zone 1 and dark red Zone 2, with a thickness of 20-200 μm; the middle region dolomite mainly developed dark red Zone 3 and very thin medium-bright red Zone 4 and bright red Zone 5, with a thickness of 7-10 μm; the near-ore end dolomite developed dark red Zone 3, medium-bright red Zone 4, and bright red Zone 5, with a thickness of 150-160 μm.

[0051] 3) The proportion of coarse to very coarse-grained dolomite in the dolomite at the far end of the ore deposit, the dolomite in the middle area, and the dolomite at the near end of the ore deposit was analyzed by the histogram of grain size of dolomite in different alteration zones. The proportion of coarse to very coarse-grained dolomite was 13-26%, and the proportion of coarse to very coarse-grained dolomite in the dolomite in the middle area and near end of the ore deposit was 52-81%.

[0052] 4) The area of ​​light gray to grayish-white coarse to very coarse crystalline dolomite belt with a coarse to very coarse crystalline dolomite content of not less than 52% and dolomite with a planer-s structure and a bright red Zone 5 with a thickness of 150-160μm is the location of the ore body in the adjacent MVT lead-zinc deposit.

[0053] The specific embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for predicting lead-zinc deposit exploration using the MVT technique, characterized in that, The specific steps are as follows: (1) Observe the host dolomite area of ​​the MVT lead-zinc deposit, identify the different alteration zones of the host dolomite, and obtain the alteration zoning pattern diagram of the dolomite; among them, the alteration zones of the host dolomite from the far end to the near end are, in order, dark gray medium-crystalline dolomite zone, gray medium-coarse-crystalline dolomite zone and light gray-grayish white coarse-very coarse-crystalline dolomite zone. (2) Collect dolomite samples from different alteration zones, grind them into probe pieces, and obtain dolomite probe piece samples from different alteration zones. (3) Single-polarized light microscopy was used to observe the dolomite probe samples with different alteration zones to identify the changes in dolomite structure from nonplaner→planer-e→planer-s from the far ore end to the near ore end, and the characteristic map of dolomite under single polarized light was obtained. (4) Cathodoluminescence microscopy was used to observe the dolomite probe samples with different alteration zones to identify five growth zones of the host dolomite and obtain cathodoluminescence microscopic feature images of dolomite with different alteration zones; the growth zones of the host dolomite from the far ore end to the near ore end are, in order, bright red Zone 1, dark red Zone 2, dark red Zone 3, medium bright red Zone 4, and bright red Zone 5. (5) Using Nano Measurer 1.2 software, quantitative grain size statistical analysis was performed on the microscopic feature images of dolomite probe specimens with different alteration zones to obtain the grain size statistical histogram of dolomite with different alteration zones. (6) Based on the characteristic images of dolomite under a single polarizing microscope, the characteristic images of dolomite under a cathodoluminescence microscope, and the grain size statistical histograms of dolomite in different alteration zones, predict the location of the ore body in the MVT lead-zinc deposit; the method for predicting the location of the ore body in the MVT lead-zinc deposit is as follows: 1) The structure of dolomite at the far end, the middle region and the near end was analyzed by the single polarizing microscope. The dolomite at the far end has a nonplaner structure, the dolomite in the middle region has a planer-e structure and the dolomite at the near end has a planer-s structure. 2) The cathodoluminescence characteristics of dolomite in different alteration zones were analyzed to determine the luminescence color and thickness of dolomite in the far-ore end, the middle region, and the near-ore end. The far-ore end dolomite mainly developed bright red Zone 1 and dark red Zone 2, with a thickness of 20-200 μm; the middle region dolomite mainly developed dark red Zone 3 and very thin medium-bright red Zone 4 and bright red Zone 5, with a thickness of 7-10 μm; the near-ore end dolomite developed dark red Zone 3, medium-bright red Zone 4, and bright red Zone 5, with a thickness of 150-160 μm. 3) Histogram analysis of grain size of dolomite in different alteration zones revealed the proportion of coarse to very coarse-grained dolomite in the dolomite at the far ore end, the middle area, and the near-ore end. The proportion of coarse to very coarse-grained dolomite was 13-26%, while the proportion of coarse to very coarse-grained dolomite in the middle area and near-ore end was 52-81%. 4) The area of ​​light gray to grayish-white coarse to very coarse crystalline dolomite belt with a coarse to very coarse crystalline dolomite content of not less than 52% and dolomite with a planer-s structure and a bright red Zone 5 with a thickness of 150-160μm is the location of the ore body in the adjacent MVT lead-zinc deposit.

2. The MVT lead-zinc deposit prospecting and prediction method according to claim 1, characterized in that: Step (4) The vacuum degree observed by the cathodoluminescence microscope is 0.3~0.4 Pa, the beam voltage is 11~12 KV, the beam current is 300~305 μA, the spot diameter is 10~10.5 mm, the gun type is a cold cathode, and the atmosphere is a vacuum.

Images