A method for evaluating the rare earth mineralization potential in carbonate rocks

Abstract

The invention discloses a method for evaluating the mineralization potential of carbonate rocks. The method takes a sample rich in calcite as a research object, uses a hot cathode microscope to determine whether it is carbonate rock, and on this basis, analyzes the rare earth element content in the calcite, and then uses the change of the rare earth content in magmatic calcite and hydrothermal calcite to determine the mineralization potential. When the mineralization potential exists, it is analyzed whether it is heavy rare earth mineralization or light rare earth mineralization. The method is simple, efficient and accurate for evaluating the rare earth mineralization potential in carbonate rocks, overcomes the problems of low efficiency and inability to determine the type of carbonate rocks in traditional geological methods, and has broad application prospects.

Description

Technical Field

[0001] The invention belongs to the field of mineral exploration and evaluation, and in particular relates to a method for evaluating the mineralization potential of carbonate rocks. Background Art

[0002] About 98% of rare earth resources come from carbonate-type rare earth deposits, among which igneous carbonate is a special type of rock from deep in the earth, mostly exposed in small veins, stocks, dykes or cones, and often closely associated with alkaline silicate rocks (such as syenite, pyroxenite, nepheline, etc.). It is extremely difficult to identify whether it is carbonate, and it is even more difficult to further evaluate the rare earth mineralization potential in carbonate. Since the main component of carbonate is calcite, which is basically consistent with the mineral composition of sedimentary carbonate or metamorphic marble, traditional prospecting methods such as geological methods have difficulties in judging whether it is carbonate. In addition, since carbonate is usually small in size in space, the activity of rare earth elements in it is relatively weak, and it is difficult to find anomalies in geochemical exploration of stream sediments, which seriously restricts the prospecting and exploration of carbonate-type rare earth deposits.

[0003] At present, the method to determine the rare earth mineralization potential in carbonate rocks is to collect calcite-rich rock samples on site, and then measure the content of rare earth oxides in the collected samples, and judge whether it has been mineralized or not by industrial grade. This method is indeed the best method to determine whether it is a mine or not, but this method is suitable for all mineral deposit exploration, and carbonate rocks are not easy to identify in the field, and are easily confused with carbonate rocks and marbles, etc., requiring technicians to have high professional knowledge. At the same time, this method cannot determine whether the carbonate rock outcrop scale has mineralization potential.

[0004] At present, there is no research on the evaluation method of the mineralization potential of carbonate rocks. Therefore, there is an urgent need to explore a new and efficient mineral exploration method to evaluate the rare earth mineralization potential in carbonate rocks, so as to quickly achieve breakthroughs in the exploration of carbonate-type rare earth deposits. Summary of the invention

[0005] The purpose of the present invention is to provide a method for evaluating the mineralization potential of carbonate rocks, which can determine whether a collected sample is carbonate rock, and at the same time determine whether the carbonate rock has the potential to form a rare earth deposit, whether it is heavy rare earth mineralization or light rare earth mineralization, with high accuracy and high prospecting efficiency, and has important practical value.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A method for evaluating the mineralization potential of carbonate rocks is provided, comprising the following steps:

[0008] 1) Delineation of mineralization areas

[0009] Identify favorable areas with potential for carbonate rare earth mineralization;

[0010] 2) Sample collection

[0011] The mineralization screened out in step 1) advantageously collects samples containing a large amount of calcite;

[0012] 3) Determine the type of magma and hydrothermal calcite

[0013] Grind the collected samples into probe pieces and take photos under a hot cathode microscope for observation. If the system is all dark red magmatic calcite, it means that the sample is magmatic calcite and has not undergone the magma-hydrothermal conversion process, and has no potential to form rare earth deposits; if the sample is all orange calcite, it means that the sample is hydrothermal calcite formed in hydrothermal and supergene environments and has no mineralization potential; if only dark red and orange calcite exist, it means that it is an igneous carbonate rock sample, and proceed to the following steps for judgment;

[0014] 4) Sample trace element analysis test

[0015] Conduct in-situ micro-area element analysis on the magma and hydrothermal calcite determined in step 3), and analyze the content of rare earth elements in the magma and hydrothermal calcite respectively, where the content of light rare earth is LREE= La+Ce+Pr+Nd+Sm+Eu, and the total content of rare earth elements is ΣREE;

[0016] 5) Determination of mineralization potential

[0017] If the ΣREE in both magma and hydrothermal calcite is less than 100 ppm, it means that the magma has a low rare earth content and is not necessarily carbonate rock, or that the carbonate rock has a low rare earth content and does not have mineralization potential;

[0018] If the ΣREE in both magma and hydrothermal calcite is greater than 100ppm, it means that the magma has a high rare earth content and is a carbonate rock, but it has not undergone the magmatic hydrothermal conversion process, and the rare earths have not been unloaded to form rare earth minerals, so there is no mineralization potential;

[0019] If the ΣREE in magmatic calcite is greater than 100 ppm, while the ΣREE in hydrothermal calcite is less than 100 ppm, it indicates that there is unloading of rare earths during the conversion from magma to hydrothermal, and there is the potential to form rare earth deposits.

[0020] 6) Identification of heavy rare earth or light rare earth mineralization potential

[0021] On the basis of determining the rare earth mineralization potential in step 5), further determine the mineralization potential of light rare earth and heavy rare earth;

[0022] If the ΣREE and LREE in magmatic calcite are both greater than 100 ppm, while the rare earth ΣREE and LREE in hydrothermal calcite are both less than 100 ppm, it indicates light rare earth unloading and has the potential to form light rare earth deposits;

[0023] If the ΣREE in magmatic calcite is greater than 100 ppm and the LREE is less than 100 ppm, while both the ΣREE and LREE in hydrothermal calcite are less than 100 ppm, it indicates heavy rare earth unloading and has the potential to form heavy rare earth deposits.

[0024] According to the above scheme, in step 1), the existing geological, geophysical, geochemical and remote sensing data in the study area are systematically collected, their mineralization potential is comprehensively analyzed, and favorable areas with possible carbonate rare earth mineralization potential are delineated.

[0025] According to the above scheme, in step 3), before taking pictures with the HC1-LM hot cathode microscope, the sample slice is first coated with gold or carbon film, the electron beam energy is 14keV, and the beam density is 9μA / mm 2 .

[0026] According to the above scheme, in step 4), laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) is used to perform in-situ micro-area element analysis.

[0027] According to the above scheme, in step 4), the rare earth elements are La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

[0028] REE is an incompatible element. It is generally believed that they will remain in the residual magma and be enriched. To form a high-grade rare earth deposit, it usually requires strong magmatic differentiation evolution and later hydrothermal superposition and transformation. Therefore, the change law of rare earth in the magma and hydrothermal evolution process is an important step in limiting rare earth mineralization. The most critical process is that in the process of carbonate magma-hydrothermal evolution, REE must be unloaded from calcite to form independent rare earth minerals to form economically valuable rare earth deposits. How to judge the unloading process of REE in carbonate magma is the key to the present invention. Therefore, the present invention uses a hot cathode microscope to determine whether it is igneous carbonate rock, which solves the problem that carbonate rock is difficult to determine in field work. On this basis, by measuring the rare earth content in magma and hydrothermal calcite, the change in the rare earth content of calcite can be used to determine whether the carbonate magma is enriched in rare earths, and whether rare earths have been unloaded during the magma-hydrothermal conversion process. The unloading process of rare earths can be used to well determine whether the carbonate rock has the potential to form a rare earth deposit; the change in the ratio of light to heavy rare earths can be used to determine whether it is a heavy rare earth unloading process or a light rare earth unloading process, thereby quickly distinguishing the mineralization process of light and heavy rare earths in carbonate rocks.

[0029] Beneficial effects of the present invention:

[0030] 1. The present invention provides a method for evaluating the rare earth mineralization potential in carbonate rocks. The sample rich in calcite is taken as the research object, and a hot cathode microscope is used to determine whether it is carbonate rock. On this basis, the rare earth element content in the calcite is analyzed, and then the mineralization potential is determined by the change of the rare earth content in the magmatic calcite and the hydrothermal calcite. When the mineralization potential exists, it is analyzed whether it is heavy rare earth mineralization or light rare earth mineralization. The method is simple, efficient and accurate for evaluating the rare earth mineralization potential in carbonate rocks, and overcomes the problems of low efficiency of traditional geological methods and inability to determine the type of carbonate rocks, and has broad application prospects.

[0031] 2. Compared with traditional exploration methods, it saves more than 80% of funds and more than 60% of time. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Graph showing the relationship between calcite LREE and ΣREE in an embodiment of the present invention.

[0033] Figure 2 This is a picture taken under a hot cathode microscope in Example 1 of the present invention.

[0034] Figure 3 This is a relationship diagram between calcite LREE and ΣREE in Example 1 of the present invention. DETAILED DESCRIPTION

[0035] The present invention is described in detail below in conjunction with the embodiments and drawings, but it should be understood that the embodiments and drawings are only used to exemplify the present invention and do not constitute any limitation on the protection scope of the present invention. All reasonable changes and combinations within the scope of the inventive concept of the present invention fall within the protection scope of the present invention.

[0036] The embodiment of the present invention provides a method for evaluating the rare earth mineralization potential in carbonate rocks, comprising the following steps:

[0037] 1) Regional data collection and comprehensive analysis

[0038] Systematically collect existing geological, geophysical, geochemical and remote sensing data in the study area, comprehensively analyze its mineralization potential, and identify favorable areas with possible carbonate rare earth mineralization potential.

[0039] 2) Sample collection

[0040] Samples containing a large amount of calcite are collected from the mineralization selected above. Each sampling point is located by GPS, coordinate data is collected, field photos are taken, and detailed field records are made for each observation point.

[0041] 3) Determine the type of magma and hydrothermal calcite

[0042] The collected samples were ground into probe pieces and carefully observed under a microscope. The size of the calcite and other information were recorded in detail. Then the color of the calcite was observed under color cathode luminescence. Since the content of Fe and rare earth elements in magmatic calcite and hydrothermal calcite is different, and iron, as the main non-luminescent element, will inhibit cathode luminescence, there will be a big difference between magmatic and hydrothermal calcite in the cathode luminescence image. The dark red calcite has a high content of iron and rare earth, which is magmatic calcite, while the orange one has a low content of iron and rare earth, which is hydrothermal calcite and sedimentary autogenous calcite. Therefore, the HC1-LM hot cathode microscope was used for photography and observation. Before observation, the thin slice was first coated with gold or carbon film, the electron beam energy was 14keV, and the beam density was 9μA / mm 2 . Use a high-sensitivity digital microscope camera to take microscopic photos, and use CL photos to determine the types of magmatic and hydrothermal calcite. If the system is all dark red magmatic calcite, it means that the sample is magmatic calcite, has not undergone the magma-hydrothermal conversion process, and does not have the potential to form rare earth deposits. If the sample is all orange calcite, it means that the sample is hydrothermal calcite formed in hydrothermal and supergene environments and has no mineralization potential. Only when both dark red and orange calcite exist, it means that the sample is an igneous carbonate rock sample, and you can proceed to the following steps to make a judgment.

[0043] 4) Sample trace element analysis test

[0044] Laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) in situ micro-area elemental analysis was carried out on magmatic and hydrothermal calcite to analyze the contents of elements such as La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu in calcite, among which the content of light rare earth LREE = La+Ce+Pr+Nd+Sm+Eu, and ΣREE is the total content of the above rare earths.

[0045] 5) Determination of mineralization potential

[0046] If the ΣREE in both magma and hydrothermal calcite is less than 100 ppm, it means that the magma has a low rare earth content and is not necessarily a carbonate rock, or that the carbonate rock has a low rare earth content and does not have mineralization potential.

[0047] If the ΣREE in both magma and hydrothermal calcite is greater than 100 ppm, it means that the magma has a high rare earth content and is a carbonate rock, but it has not undergone a magmatic hydrothermal conversion process, the rare earths have not been unloaded to form rare earth minerals, and therefore has no mineralization potential.

[0048] If the ΣREE in magmatic calcite is greater than 100 ppm, while the rare earth in hydrothermal calcite is less than 100 ppm, it indicates that there is unloading of rare earths during the conversion from magma to hydrothermal, and there is the potential to form rare earth deposits.

[0049] 6) Identification of heavy rare earth or light rare earth mineralization potential

[0050] Process the analysis data from step 4) and draw a LREE vs. ΣREE plot. For details, see Figure 1 , the mineralization potential of light rare earth and heavy rare earth can be determined through this relationship diagram;

[0051] If the ΣREE and LREE in the magmatic calcite are greater than 100 ppm, the Figure 1 The rare earth ΣREE and LREE in hydrothermal calcite are less than 100 ppm, falling in region 2. Figure 1 Area 4 in the figure indicates light rare earth unloading and has the potential to form light rare earth deposits;

[0052] If the magmatic calcite ΣREE is greater than 100ppm and LREE is less than 100ppm, it falls in Figure 1 In region 3, the hydrothermal calcite ΣREE and LREE are less than 100 ppm, falling in Figure 1 Area 4 in the figure indicates heavy rare earth unloading and has the potential to form heavy rare earth deposits.

[0053] Example 1

[0054] A method for evaluating the rare earth mineralization potential in carbonate rocks is provided, comprising the following steps:

[0055] (1) A set of samples containing calcite were collected at the coordinates of N36°18′43″, E101°49′56″

[0056] (2) Probe the sample and then take photos under a hot cathode microscope. Figure 2 ), there are dark red magmatic calcite and orange hydrothermal calcite, indicating that the sample is an igneous carbonate rock sample, not calcite formed during the sedimentation process.

[0057] (3) The rare earth content in magma and hydrothermal calcite analyzed by LA-ICP-MS is shown in Table 1:

[0058] Table 1. Rare earth content in samples of Example 1 (ppm)

[0059]

[0060] (4) Determination of mineralization potential: The ΣREE in magmatic calcite is greater than 100 ppm, while the rare earth in hydrothermal calcite is less than 100 ppm, indicating that there is rare earth unloading during the conversion from magma to hydrothermal, and there is the potential to form rare earth deposits.

[0061] (5) Identification of heavy rare earth or light rare earth mineralization potential: Draw a LREE vs. ΣREE relationship diagram, see Figure 3 , where magmatic calcite falls Figure 3 in region 2, while hydrothermal calcite falls Figure 3 In Area 4, there is unloading of light rare earths, which has the potential to form light rare earth deposits. The super-large Shangzhuang REE-P deposit was discovered in this area.

[0062] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. A method for evaluating the rare earth mineralization potential in carbonate rocks, characterized in that: The following steps are involved: 1) Delineation of mineralization areas Identify favorable areas with potential for carbonate rare earth mineralization; 2) Sample collection The mineralization screened out in step 1) advantageously collects samples containing calcite; 3) Determine the type of magma and hydrothermal calcite Grind the collected samples into probe pieces, take photos and observe them under a hot cathode microscope. When dark red magmatic calcite and orange hydrothermal calcite are observed at the same time, proceed to the following steps for judgment; 4) Sample trace element analysis test Conduct in-situ micro-area element analysis on the magma and hydrothermal calcite determined in step 3), and analyze the content of rare earth elements in the magma and hydrothermal calcite respectively, where the content of light rare earth is LREE= La+Ce+Pr+Nd+Sm+Eu, and the total content of rare earth elements is ΣREE; 5) Determination of mineralization potential If the ΣREE in both magmatic and hydrothermal calcite is less than 100 ppm, it has no mineralization potential; If the ΣREE in both magmatic and hydrothermal calcite is greater than 100 ppm, it has no mineralization potential; If the ΣREE in magmatic calcite is greater than 100ppm, and the ΣREE in hydrothermal calcite is less than 100ppm, it has the potential to form rare earth deposits; 6) Identification of heavy rare earth or light rare earth mineralization potential On the basis of determining the rare earth mineralization potential in step 5), further determine the mineralization potential of light rare earth and heavy rare earth; If the ΣREE and LREE in magmatic calcite are both greater than 100 ppm, and the rare earth ΣREE and LREE in hydrothermal calcite are both less than 100 ppm, there is the potential to form light rare earth deposits; If the ΣREE in magmatic calcite is greater than 100 ppm and the LREE is less than 100 ppm, while both the ΣREE and LREE in hydrothermal calcite are less than 100 ppm, there is the potential to form heavy rare earth deposits.

2. The method for evaluating the rare earth mineralization potential in carbonate rocks according to claim 1, characterized in that: In the step 3), before taking photos and observing with the hot cathode microscope, the sample slice is first coated with gold or carbon film.

3. The method for evaluating the rare earth mineralization potential in carbonate rocks according to claim 1, characterized in that: In step 3), the electron beam energy of the hot cathode microscope is 14 keV, and the beam density is 9 μA / mm 2 .

4. The method for evaluating the rare earth mineralization potential in carbonate rocks according to claim 1, characterized in that: In the step 3), if the system contains dark red magmatic calcite, it means that the sample is magmatic calcite, has not undergone the magma-hydrothermal conversion process, and does not have the potential to form a rare earth deposit; if the sample contains orange calcite, it means that the sample is hydrothermal calcite formed in a hydrothermal and supergene environment and does not have mineralization potential; only when both dark red and orange calcite exist, proceed to the following step for judgment.

5. The method for evaluating the rare earth mineralization potential in carbonate rocks according to claim 1, characterized in that: In the step 4), laser ablation inductively coupled plasma mass spectrometry is used to perform in-situ micro-area element analysis.

6. The method for evaluating the rare earth mineralization potential in carbonate rocks according to claim 1, characterized in that: In the step 4), the rare earth elements are La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

Images