Place type deposit prospecting method based on geochemical characteristics of sphene minerals
By collecting intrusive rock samples from the mining area in porphyry deposits, testing the titanite element data and determining the oxygen fugacity and water content, and eliminating hydrothermal titanite, the problem of low prospecting efficiency was solved, and efficient and accurate prospecting for porphyry deposits was achieved.
Patent Information
- Application Number
- CN202510816489.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-18
- Publication Date
- 2025-09-05
AI Technical Summary
The existing technology for prospecting porphyry deposits is inefficient and requires a lot of time for drilling and core logging.
By collecting intrusive rock samples in the mining area, testing the elemental data of titanite, using the oxygen fugacity and water content discrimination method to determine whether the porphyry body is a mineral-bearing rock body, eliminating hydrothermal titanite to improve detection accuracy, and using polarizing microscope and scanning electron microscope combined with electron probe and laser ablation inductively coupled plasma mass spectrometry to obtain elemental data.
No drilling construction and core logging are required, which significantly shortens field work time and improves prospecting efficiency and accuracy.
Smart Images
Figure CN120594514A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of minerals, and in particular relates to a method for prospecting porphyry deposits based on the geochemical characteristics of sphene minerals. Background Art
[0002] Porphyry deposits, a significant global source of copper, molybdenum, gold, and other metals, are typically characterized by large scale, stable mineralization grades, low burial depths, high adaptability to open-pit mining, and excellent ore processing capabilities. Due to the multi-phase nature of magmatic activity, porphyry deposits often contain multiple intrusions from different periods. However, not every intrusion is ore-bearing, making the identification of ore-bearing intrusions a primary task in porphyry deposit exploration.
[0003] In existing technologies, finding ore-bearing porphyry bodies within porphyry deposits typically requires field drilling and sampling, followed by core observation and chemical analysis to determine whether the intrusion is a ore-bearing porphyry body. However, the time required for drilling and core logging in existing technologies results in low prospecting efficiency. Summary of the Invention
[0004] The present invention provides a porphyry deposit prospecting method based on the geochemical characteristics of sphene minerals, which aims to solve the problem of low prospecting efficiency in the prior art.
[0005] In order to achieve the above object, the present invention provides a porphyry deposit prospecting method based on the geochemical characteristics of sphene minerals, comprising the following steps:
[0006] S1, collecting intrusive rock samples from the mining area;
[0007] S2, elemental data of sphene in intrusive rock samples;
[0008] S3, using the obtained element data to determine oxygen fugacity and water content;
[0009] S4, if both the oxygen fugacity and water content standards are met, the rock mass is a mineral-bearing intrusive rock.
[0010] This approach involves collecting intrusive rock samples from mining areas, then performing elemental testing to obtain elemental data. This elemental data is then used to determine oxygen fugacity and water content, ultimately determining whether the porphyry is ore-bearing. This prospecting method, disclosed in this approach, eliminates the need for drilling and core logging, significantly reducing fieldwork time and improving prospecting efficiency.
[0011] To improve detection accuracy, hydrothermal titanite is preferably removed from the sample. In S1 of this solution, the intrusive rock sample is observed under a microscope to determine the occurrence of titanite in the intrusive rock sample. The occurrence of titanite in the intrusive rock sample is then determined to determine whether it meets the exclusion criteria. If not, the subsequent steps are performed. After hydrothermal titanite is identified and removed through microscopy, the validity of subsequent analytical data is significantly improved, enhancing the accuracy of prospecting.
[0012] To ensure accurate screening, preferably, the occurrence of sphene in the intrusive rock sample is first observed using a polarizing microscope for preliminary screening and removal. Then, the occurrence of sphene in the intrusive rock sample is observed using a scanning electron microscope. This approach uses polarizing microscope observation to initially remove hydrothermal sphene. A secondary screening observation using a scanning electron microscope is then performed. Scanning electron microscopy provides a clearer view of the occurrence and structure of sphene, helping to obtain more accurate information and improve screening accuracy.
[0013] To improve detection accuracy, hydrothermal titanite is preferably removed from the sample. In step S2 of this solution, the elemental data obtained is used to determine whether the titanite in the intrusive rock sample meets the exclusion criteria for hydrothermal titanite. If it does not meet the exclusion criteria, subsequent steps are performed. The elemental data obtained allows for more accurate identification of hydrothermal titanite, which is then removed to ensure the accuracy of subsequent testing.
[0014] Preferably, in order to facilitate observation of the intrusive rock sample, in S1 of this solution, the intrusive rock sample is made into a probe sheet. By making the intrusive rock sample into a probe sheet for observation, accurate observation of the intrusive rock sample can be facilitated.
[0015] Preferably, the thickness of the probe sheet is preferably 0.05 mm to 0.07 mm.
[0016] Preferably, in order to accurately obtain the major element data of sphene, in S2 of this solution, an electron probe test is performed on the sphene in the intrusive rock sample to obtain the major element data of the sphene.
[0017] Preferably, the main element data include element data of CaO, TiO2, Al2O3, Fe2O3 and F.
[0018] Preferably, to accurately obtain trace element data for sphene, in step S2 of this solution, after completing the electron probe test, the sphene sample is subjected to laser ablation inductively coupled plasma mass spectrometry to obtain trace element data for the sphene. This solution facilitates the distinction between hydrothermal sphene and igneous sphene by identifying trace elements and analyzing the trace element data, thereby improving prospecting accuracy.
[0019] Preferably, the trace element data includes element data of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y.
[0020] To improve prospecting accuracy and eliminate hydrothermal titanite, this solution selects rare earth elements from the trace elements and uses them to create a rare earth element distribution curve. This rare earth element distribution curve further eliminates hydrothermal titanite, ensuring the accuracy of subsequent prospecting.
[0021] The beneficial effects of this invention lie in: This solution collects intrusive rock samples from mining areas, then performs elemental testing to obtain elemental data. Based on this data, oxygen fugacity and water content are determined to ultimately determine whether the porphyry body is ore-bearing. The prospecting method disclosed in this solution does not require drilling or core logging, significantly reducing field work time and improving prospecting efficiency. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 The figure is a flow chart of a prospecting method for porphyry deposits based on the geochemical characteristics of sphene minerals. DETAILED DESCRIPTION
[0023] In order to make the objectives, technical solutions and advantages of the embodiments more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. Instead, they are merely examples of devices and methods consistent with certain aspects of the present disclosure as detailed in the appended claims.
[0024] In this disclosure, unless otherwise stated, directional terms such as "inner" and "outer" are defined based on the contours of the corresponding components. Terms such as "first" and "second" used in this disclosure are intended to distinguish one element from another and do not have a sequential or important meaning.
[0025] Example 1
[0026] Basically as attached Figure 1 As shown, a method for prospecting porphyry deposits based on the geochemical characteristics of sphene minerals includes the following steps:
[0027] S1, collect different types of intrusive rock samples in the mining area and make the intrusive rock samples into probe pieces.
[0028] To distinguish different types of intrusive rock samples, each sample can be numbered, such as QDP-1, QDP-2, QDP-3, and so on. The number of intrusive rock samples collected depends on the actual testing needs. For example, if only two types of intrusive rock samples are needed, two samples are sufficient; if three types of intrusive rock samples are needed, three samples are sufficient. The collected intrusive rock samples are located at the surface, eliminating the need for drilling and core logging, which improves sampling and prospecting efficiency.
[0029] The probe sheet of this embodiment is rectangular in shape, with a thickness of preferably 0.05 mm to 0.07 mm, and more preferably 0.06 mm. This thickness prevents insufficient thickness due to laser ablation. The probe sheet can be 50 mm x 25 mm in size, allowing for simultaneous placement of up to three samples for probe testing. This reduces the number of probe sheet changes and the time required to replace them, thereby improving work efficiency.
[0030] In order to remove hydrothermal sphene from the intrusive rock samples, this embodiment first observes the occurrence of sphene in the intrusive rock samples using a polarizing microscope and performs preliminary screening; then, the occurrence of sphene in the intrusive rock samples is observed using a scanning electron microscope and screened out again.
[0031] The occurrence of sphene in the intrusive rock sample described in this step includes the euhedral degree, particle size and paragenetic combination of sphene.
[0032] Initial screening criteria include sphene particle size, the association of sphene with hydrothermal minerals, and the euhedral nature of the sphene. If the sphene particle size is small (less than 100 μm), the sphene is associated with hydrothermal minerals, and the euhedral nature of the sphene is poor, it indicates hydrothermal sphene and requires screening. Otherwise, proceed to the next step.
[0033] During re-screening, the criteria for re-screening are sphene associated with hydrothermal minerals (e.g., potassium feldspar, chlorite, epidote, etc.) and sphene that meets the rejection criteria for euhedral degree. The rejection criteria for euhedral degree can be set by the user.
[0034] It should be noted that this embodiment discloses a method of preliminary observation and screening using a polarizing microscope, followed by observation using a scanning electron microscope. However, in other embodiments, other observation methods known in the art may be used to observe intrusive rock samples and screen out intrusive rock samples that meet the screening criteria. The purpose of microscopic identification and screening in this step is to eliminate hydrothermal titanite samples, ensuring that the titanite used in subsequent analysis is, as much as possible, igneous titanite, avoiding interference with the analysis and improving the accuracy of subsequent screening.
[0035] S2: Electron microprobe testing is performed on the intrusive rock sample made into the probe sheet to obtain major element data for sphene. After the electron microprobe testing is completed, the sphene sample is then subjected to laser ablation inductively coupled plasma mass spectrometry testing to obtain trace element data for sphene.
[0036] The major element data obtained in this step include the content data of elements such as CaO, TiO2, Al2O3, Fe2O3 and F. The trace element data include the content data of elements such as La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y.
[0037] In this example, the electron probe analysis was preferably performed using a JEOL JXA-8100 electron probe microanalyzer. This analytical device is equipped with a characteristic X-ray probe that collects characteristic X-rays of various elements, enabling electron probe composition analysis. This device also features high precision, rapid analysis, and ease of use.
[0038] In this embodiment, when performing laser ablation inductively coupled plasma mass spectrometry testing, in order to improve the accuracy and efficiency of the test, the first 20 s of the analysis work are used as the background signal, the middle 40 s are used as the laser ablation signal, and the last 20 s are used as the blank signal, with a total analysis time of 80 s. By using the background signal in the first 20 s and the blank signal in the last 20 s, the accuracy of the data is ensured, errors are reduced, instrument abnormalities are checked, and measurement accuracy is optimized, which helps to obtain stable and reliable analysis results. At the same time, when the device is working, the laser beam spot size is 40 μm, the sample movement speed is 15~40 μm / s, the beam spot energy density reaches 2 J / cm², and the ablation frequency is 8Hz.
[0039] By obtaining major and trace element data for sphene, we can more accurately distinguish hydrothermal sphene from magmatic sphene, thereby more accurately eliminating hydrothermal sphene. The physical properties and chemical element profiles of hydrothermal sphene and magmatic sphene differ significantly. During screening, hydrothermal sphene and magmatic sphene can be distinguished based on their physical properties and chemical element profiles.
[0040] Screening by physical properties: Magmatic titanite coexists with magmatic minerals such as hornblende, plagioclase, and quartz, has good euhedral form, mostly wedge-shaped, but also envelope-shaped, with straight boundaries and large mineral grains (>100 μm). Hydrothermal titanite coexists with hydrothermal minerals such as potassium feldspar, chlorite, epidote, and biotite, has poor euhedral form, irregular shape, smooth boundaries, and small mineral grains (<100 μm).
[0041] Screening by chemical properties: Magmatic titanite has a high Th / U ratio, mostly greater than 1. Hydrothermal titanite has a low Th / U ratio, mostly less than 1.
[0042] It should be noted that this embodiment discloses obtaining elemental data of sphene by combining electron probe testing and laser ablation inductively coupled plasma mass spectrometry testing. The screening accuracy of hydrothermal sphene and igneous sphene is higher, which improves the accuracy of the test results.
[0043] S3, after completing the above screening steps, the oxygen fugacity and water content are judged based on the obtained element data.
[0044] The criteria for identification are: when the Eu / Eu* value of sphene is greater than 0.4 and the Ce / Ce* value is between 0.92 and 1.27, the melt in which the sphene was formed is a high oxygen fugacity environment; otherwise, it is a low oxygen fugacity environment. When the La / Yb value is between 3.957507 and 40.827589 and the Sr / Y ratio is between 0.010752 and 0.225818, the sphene was formed in a water-rich environment. At the same time, when the Eu / Eu* / Y ratio is between 1.29×10 -4 –0.002604, the Ce / Nd / Y ratio is 5.150000×10 -4 The range of –0.025588 indicates that sphene was formed in a water-rich environment.
[0045] S4. If the titanite sample meets the standards of oxygen fugacity and water content at the same time, then the rock mass is a mineral-bearing intrusive rock; otherwise, it is a non-mineralized intrusive rock.
[0046] Example 2
[0047] The difference between this embodiment and embodiment 1 is that in S2 of this embodiment, rare earth elements are selected from the trace elements, and a rare earth element distribution curve is prepared using the rare earth element distribution curve, so that hydrothermal titanite can be further accurately removed.
[0048] In S2, if the rare earth element distribution curve shows a right-dipping type and negative Eu / Eu* is obvious, it is magmatic titanite; if the rare earth element distribution curve shows a left-dipping type or is enriched in rare earths and positive Eu / Eu* is obvious, it is hydrothermal titanite.
[0049] Comparative Example 1
[0050] The difference between this comparative example and Example 1 is that the thickness of the probe sheet in this comparative example is set to 0.07 mm.
[0051] Comparative Example 2
[0052] The difference between this comparative example and Example 1 is that the thickness of the probe sheet in this comparative example is set to 0.08 mm.
[0053] Comparative Example 3
[0054] The difference between this comparative example and Example 1 is that the thickness of the probe sheet in this comparative example is set to 0.05 mm.
[0055] Comparative Example 4
[0056] The difference between this comparative example and Example 1 is that the thickness of the probe sheet in this comparative example is set to 0.04 mm.
[0057] The probe pieces obtained in Example 1, Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4 were observed under a microscope and tested by laser ablation inductively coupled plasma mass spectrometry, and the following results were obtained.
[0058] Table 1
[0059] From Table 1 we can see that:
[0060] (1) When the thickness of the probe sheet is between 0.05 and 0.07 mm, microscopic observation and laser ablation inductively coupled plasma mass spectrometry testing can be carried out normally, thus facilitating the final acquisition of accurate detection results.
[0061] (2) When the thickness of the probe piece is less than 0.05 mm, the thickness of the probe piece is too small, and the probe piece will be damaged during the laser ablation inductively coupled plasma mass spectrometry test, causing the laser ablation inductively coupled plasma mass spectrometry test to fail and the final test result cannot be obtained.
[0062] (3) When the thickness of the probe sheet is less than 0.07 mm, the thickness of the probe sheet is too large and the microscope cannot observe the occurrence of sphene through the probe sheet, resulting in inaccurate detection results.
[0063] The above is only an embodiment of the present invention, and the common knowledge such as the specific structure and characteristics of the scheme is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several variations and improvements can be made, which should also be regarded as the scope of protection of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.
Claims
1. A method for prospecting porphyry deposits based on the geochemical characteristics of sphene minerals, characterized by: The following steps are included: S1, collecting intrusive rock samples from the mining area; S2, elemental data of sphene in intrusive rock samples; S3, using the obtained element data to determine oxygen fugacity and water content; S4, if both the oxygen fugacity and water content standards are met, the rock mass is a mineral-bearing intrusive rock.
2. The prospecting method according to claim 1, wherein: In S1, the intrusive rock sample is observed under a microscope to obtain the occurrence of sphene in the intrusive rock sample; Determine whether the occurrence of sphene in the intrusive rock sample meets the screening criteria. If not, proceed to the subsequent steps.
3. The prospecting method according to claim 1 or 2, characterized in that: In S2, the element data obtained are used to determine whether the sphene in the intrusive rock sample meets the screening criteria for hydrothermal sphene. If it does not meet the screening criteria, the subsequent steps are performed.
4. The prospecting method according to claim 1, wherein: In the above-mentioned S1, the intrusive rock sample is made into a probe piece.
5. The prospecting method according to claim 4, characterized in that: The thickness of the probe sheet is 0.05 mm to 0.07 mm.
6. The prospecting method according to claim 4, characterized in that: In S2, the sphene in the intrusive rock sample is subjected to an electron probe test to obtain major element data of the sphene.
7. The prospecting method according to claim 6, characterized in that: The major element data include CaO, TiO2, Al2O3, Fe2O3 and F element data.
8. The prospecting method according to claim 6, characterized in that: In S2, after the electron probe test is completed, the sphene sample is subjected to a laser ablation inductively coupled plasma mass spectrometry test to obtain trace element data of the sphene.
9. The prospecting method according to claim 8, characterized in that: The trace element data include La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y element data.
10. The prospecting method according to claim 8, characterized in that: Rare earth elements are selected from trace elements, and rare earth element distribution curves are prepared using rare earth element examples.