Gold ore prospecting method based on biotite altered mineral mapping

Abstract

The invention discloses a gold ore prospecting method based on biotite alteration mineral mapping, which comprises the following steps: (1) according to pit exploration, drilling and surface outcrop conditions of a gold ore exploration area, systematically collecting representative samples containing mineralized alteration biotite on a contact zone of an ore body and surrounding rock; (2) grinding the alteration zone sample into a probe sheet, analyzing through an electronic probe to obtain the main component of biotite, calculating the alteration strength parameter Mg / (Mg + Fe) atomic ratio and the like of biotite, and calculating the mineralization alteration temperature by using a biotite Ti thermometer; and (3) based on the sampling position, carrying out space mapping on the alteration intensity and the alteration temperature, and delineating a prediction region with high alteration intensity and high alteration temperature as a deep edge prospecting target region according to the disclosed positive correlation between the biotite alteration intensity and the ore body thickness and between the alteration temperature and the ore body grade.

Description

Technical Field

[0001] The present invention belongs to the field of mineral exploration and evaluation, and particularly relates to a prospecting method for the deep margin of a gold mining area based on biotite alteration mineral mapping. By using the chemical composition of biotite, the alteration mineralization intensity and temperature are calculated to judge the extension trend of high-grade thick ore bodies, and prospecting target areas are arranged accordingly. Background Art

[0002] Alteration mineral mapping is an important and direct means to evaluate the mineralization trend, so it is often used to delineate prospecting target areas for gold deposits. At present, the multi-spectral portable analyzers used for alteration mineral mapping, although having the characteristics of simple and rapid analysis, the spectral measurement belongs to semi-quantitative analysis, and the probe aperture of the analyzer is relatively large, making it difficult to accurately identify samples of smaller alteration minerals. Therefore, the biotite alteration mineral mapping method based on the mature and popular electron probe analysis is not only simple and easy to operate and belongs to quantitative analysis, but also because the electron probe analysis beam spot can be as low as 1 micron, it overcomes the problems caused by smaller alteration minerals. Summary of the Invention

[0003] The present invention provides a gold prospecting method based on biotite alteration mineral mapping. This method is based on electron probe analysis to determine parameters such as the alteration intensity and alteration temperature of altered biotite at different spatial positions, so as to evaluate the extension direction of high-grade thick ore bodies, and thus delineate prospecting target areas for the deep margin.

[0004] To achieve the above object, the present invention adopts the following technical solutions: A gold prospecting method based on biotite alteration mineral mapping, comprising the following steps: (1) According to the adit, drilling and surface outcrop conditions in the gold ore exploration area, systematically collect representative samples of mineralized altered biotite on the contact zone between the ore body and the surrounding rock; (2) After grinding the alteration zone samples into probe slices, obtain the main components of biotite through electron probe analysis, calculate the alteration intensity parameter such as the Mg / (Mg+Fe) atomic ratio of biotite, and calculate the mineralization alteration temperature using the biotite Ti thermometer; (3) Based on the sampling positions, project the alteration temperature and intensity spatially. According to the positive correlation between the revealed biotite alteration intensity and the ore body thickness, and between the alteration temperature and the ore body grade, circle the prediction areas with large alteration intensity and high alteration temperature as prospecting target areas for the deep margin.

[0005] Further, in step (1), 3-5 representative biotite samples of the alteration zone are collected at each engineering position, and the samples are larger than 3×3×5 cm.

[0006] Furthermore, the biotite test components in step (2) include SiO2, TiO2, Al2O3, FeO, MnO, MgO, CaO, Na2O, K2O, F and Cl; the alteration intensity Mg / (Mg+Fe) and other parameters are calculated based on the atomic ratio; the formula for calculating the mineralization alteration temperature based on the biotite Ti thermometer of Henry et al. (2005) is: T = {[ln(Ti) – a – c( X Mg ) 3 ] / b} 0.333 ,in, X Mg = Mg / (Mg + Fe), a = –2.3594, b = 4.6482 × 10 –9 , c = –1.7283, applicable range X Mg = 0.275–1.000, Ti = 0.04–0.60 apfu, T = 480–800 °C.

[0007] Furthermore, in step (3), based on the positive correlation between biotite alteration intensity and ore body thickness, and alteration temperature and ore body grade, the extension direction of the high-grade and thick mineralized body is delineated.

[0008] Furthermore, this method is suitable for prospecting in the deep margins of gold mining areas where biotite alteration minerals are developed during the survey and exploration stages.

[0009] The beneficial effects of the present invention are as follows: The present invention proposes a method for prospecting in the deep edge of a gold mining area based on biotite altered mineral mapping, which belongs to the technical field of mineral resource exploration, solves the problem of small number and small particle size of altered minerals for existing multi-spectral analysis prospecting methods belonging to semi-quantitative analysis, and the single sample usage of the present invention is small and non-destructive, which is convenient for further carrying out other research. The present invention calculates parameters such as alteration intensity and alteration temperature according to altered mineral biotite samples of different exploration degrees, different exploration grids, and different engineering locations in the gold mining area, performs three-dimensional mapping according to the spatial position, analyzes the extension direction of high-grade thick gold ore bodies, and quickly delineates prospecting target areas. Samples containing altered mineral biotite are easy to obtain in the field and can be identified by the naked eye. The difficulty and cost of making probe sheets and electronic probe analysis are relatively small, and the sample is not damaged after analysis. The present invention not only improves the prospecting efficiency and success rate, but also greatly reduces the exploration time and cost, which is of great significance for prospecting in the deep edge of a gold mining area where biotite altered minerals are developed. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 The composition difference between the mineralized altered biotite and metamorphic biotite in the Dulanggou gold deposit; Figure 2 The alteration intensity of biotite in the mineralization alteration of Dulanggou Gold Mine is positively correlated with the thickness of the ore body; Figure 3 The Ti temperature of biotite in the mineralization alteration of Dulanggou Gold Mine is positively correlated with the grade of the ore body; Figure 4 It is a simplified vertical longitudinal projection diagram for estimating the resource volume of Orebody 1 in Dulanggou Gold Mine. Detailed implementation manners

[0011] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. Embodiment

[0012] A prospecting method for the deep edge of a gold mining area based on biotite alteration mineral mapping: Taking Dulanggou Gold Mine in Danba County, Sichuan Province as an example, it specifically includes the following steps: (1) Through field geological surveys and adit and drill hole logging, altered biotite samples are obtained at 78 locations on the contact alteration zone between the ore body and the surrounding rock in Dulanggou Gold Mine.

[0013] (2) At each engineering location, 3 - 5 representative biotite samples from the alteration zone are collected. The samples are larger than 3×3×5 cm, and the spatial positions (X, Y, Z) are registered.

[0014] (3) Sample preparation: The samples collected in the field are ground into probe slices (length × width is 25 mm × 50 mm, thickness is 0.03 - 0.1 mm), and fresh biotite grains are selected and circled under a polarized light microscope.

[0015] (4) Sample testing: After the probe slices are carbon - sprayed, the main components (SiO2, TiO2, Al2O3, FeO, MnO, MgO, CaO, Na2O, K2O, F, Cl) of the circled biotite grains are determined using an electron probe analyzer.

[0016] (5) Data processing: Calculate alteration intensity parameters such as Mg / (Mg + Fe) according to the atomic ratio ( Figure 1 、 Figure 2 ); Import parameters such as the number of Ti atoms, X Mg etc. into an Excel calculation sheet, and calculate the alteration mineralization temperature according to the biotite Ti thermometer formula of Henry et al. (2005) ( Figure 3 ).

[0017] (6) Ore prospecting target area delineation: Based on the spatial positions of the biotite samples collected from the alteration zones, planar and sectional projections are made, and isograms of alteration intensity and alteration temperature are produced. According to the revealed law that there is a positive correlation between the biotite alteration intensity and the ore body thickness, and between the alteration temperature and the ore body grade ( Figure 2 , Figure 3 ), the extension direction of the high-grade and thick gold mineralization bodies is determined. In the area where the alteration intensity is continuous and the alteration temperature continues to increase in the deep part north of the Dulanggou Gold Mine, it is delineated as the ore prospecting target area. Through the verification of adit and borehole construction, a new high-grade gold ore body ( Figure 4 ) is discovered. The thickness of the ore body is 2.3 m and the grade is 8.6 g / t, which proves the effectiveness of the proposed ore prospecting method based on biotite alteration mineral mapping this time.

Claims

1. A gold prospecting method based on biotite alteration mineral mapping, characterized in that: The following steps are involved: (1) Based on the pit exploration, drilling and surface outcrop conditions in the gold exploration area, systematically collect representative samples of mineralized altered biotite in the contact zone between the ore body and the surrounding rock; (2) After the alteration zone samples were ground into probe pieces, the main components of biotite were obtained by electron probe analysis, and the alteration intensity parameters of biotite, such as the atomic ratio of Mg / (Mg+Fe), were calculated. The biotite Ti thermometer of Henry et al. (2005) was used to calculate the mineralization alteration temperature. The calculation formula of the biotite Ti thermometer is: T = {[ln(Ti) – a – c( X Mg ) 3 ] / b} 0.333 ,in X Mg = Mg / (Mg + Fe), a = –2.3594, b = 4.6482 × 10 –9 , c = –1.7283, applicable range X Mg = 0.275–1.000, Ti = 0.04–0.60 apfu, T = 480–800 °C; (3) Based on the sampling location, the alteration intensity and alteration temperature are spatially mapped. According to the positive correlation between biotite alteration intensity and ore body thickness, and between alteration temperature and ore body grade, the predicted area with high alteration intensity and high alteration temperature is identified as the deep edge prospecting target area.

2. A gold prospecting method based on biotite alteration mineral mapping according to claim 1, characterized in that: In step (1), 3-5 representative alteration zone biotite samples are collected at each engineering location, and the samples are larger than 3×3×5 cm.

3. A gold prospecting method based on biotite alteration mineral mapping according to claim 1, characterized in that: The biotite components in step (2) include SiO2, TiO2, Al2O3, FeO, MnO, MgO, CaO, Na2O, K2O, F and Cl.

4. A gold prospecting method based on biotite alteration mineral mapping according to claim 1, characterized in that: It has been revealed that the intensity of biotite alteration is positively correlated with the thickness of the ore body, and the alteration temperature is positively correlated with the grade of the ore body.

5. A gold prospecting method based on biotite alteration mineral mapping according to claim 1, characterized in that: It is simple and easy to operate. The main testing method, electronic probe, is mature and popular. It is suitable for prospecting in the deep edges of gold mining areas where biotite alteration minerals are developed from the survey to the exploration stage.

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