A method for determining the position of barite deposition center by using sulfur isotope values

Abstract

The present invention discloses a method for judging the position of barite deposition center by using sulfur isotope values, which comprises the following steps: (1) taking barite samples and performing crushing and pretreatment; (2) weighing samples meeting the working standards, tightly wrapping them with special tin capsules, and storing them in a desiccator; (3) the samples fall into the EA reaction furnace through an automatic sampler and burn instantaneously; (4) adding oxygen to assist the full decomposition of the samples, and the products are purged by ammonia and enter the separation column; (5) the separated SO2 enters the IRMS for δ 34 S determination; (6) judging the position of the deposition center according to the δ 34 S value. The present invention adopts EA-IRMS to analyze sulfur isotopes online and judges the position of the deposition center according to δ 34 S. The results are accurate and widely applicable. This identification method provides working steps and specific indicators for correctly judging the barite deposition center, provides new ideas for the research on barite deposition and mineralization, and is of great significance for the exploration and discovery of new types of super-large barite deposits in China and for solving the problem of the bottleneck of barite resources.

Description

Technical Field

[0001] The present invention belongs to the field of geological prospecting for minerals, and particularly relates to a method for judging the position of barite sedimentation center by using sulfur isotope values. Background Art

[0002] China is one of the countries with the richest reserves of barite resources in the world. The deposits are mainly distributed in the Qinling Mountains on the northern margin of the Yangtze Block and the Jiangnan area on the southern margin. Guizhou is located in the southwestern margin of the Jiangnan barite metallogenic belt, and it is the area with the richest barite resources, the most representative and research value of deposit types in this metallogenic belt. As one of the dominant minerals in Guizhou Province, sedimentary barite ore is the most typical, mainly distributed in areas such as Tianzhu, Yuping, Zhenning, Majiang, etc. Tianzhu has the world's largest sedimentary barite deposit, and the Zhenning sedimentary barite deposit reaches 70 million tons. However, most of them are mainly small deposits, and the proportion of large and super-large deposits is significantly low.

[0003] A large number of studies show that Guizhou has great potential and prospects for barite prospecting. For example, the mineralization of the Zhenning Leji Devonian barite deposit shows obvious regularity. Evidence from many aspects indicates that the center of barite mineralization is likely to be close to the Leji area. Moreover, the southeastern extension section and the western area of the Leji mining area show good prospecting potential. Another example is that the geological characteristics and element / isotope compositions of the Tianzhu barite deposit also show certain regular changes in the Yundong and Dahebian mining areas. Moreover, the changes in the redox state of seawater, oxygen fugacity, and sulfate concentration under the restriction of biological action in the ore-controlling basin are considered to have an important control on the differential mineralization of regional barite. In addition, large-scale stratiform lead-zinc ore bodies have been newly discovered in the Doushantuo Formation strata under the Tianzhu Yundong barite deposit, and they are likely to belong to the same metallogenic system. Due to the lack of a method for judging the sedimentation center, traditional methods such as a large number of boreholes and profile measurements have been used for a long time to judge the sedimentation center, which requires a large amount of manpower and financial resources, restricts the discovery and evaluation of barite deposits, and leads to the long-term failure to find barite deposits in China or the high cost of prospecting. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for judging the position of barite sedimentation center by using sulfur isotope values. This method uses EA-IRMS to analyze sulfur isotopes online and judges the position of the sedimentation center according to the δ 34 S value, so as to solve the problems of the large difficulty in prospecting for existing barite deposits and the high cost of determining the sedimentation center and the distribution of ore bodies.

[0005] To achieve the above purpose, the technical solution of the present invention is realized as follows:

[0006] A method for judging the position of barite sedimentation center by using sulfur isotope values, comprising the following steps:

[0007] (1) Select barite ore deposits exposed on the surface within the ore-forming area and barite samples from existing drill holes, and perform crushing and pretreatment on the samples.

[0008] (2) Weigh 5 mg of samples that meet the working standards, wrap them tightly with special tin capsules, and store them in a desiccator for later use.

[0009] (3) The samples fall into the EA reaction furnace through an automatic sampler and burn instantly.

[0010] (4) During the reaction, oxygen is added to assist the complete decomposition of the samples, and the products are purged by ammonia and enter the separation column.

[0011] (5) The separated SO2 enters the IRMS for the determination of δ 34 S.

[0012] (6) Based on the δ 34 S value, determine the position of the deposition center: when the δ 34 S value is relatively high, the sampled location is closer to the deposition center; when the δ 34 S value is medium, the sampled location is at a moderate distance from the deposition center; when the δ 34 S value is relatively low, the sampled location is far from the deposition center.

[0013] Optionally, in step (1), the pretreatment of the barite sample crushing includes crushing the massive barite, grinding it into powder, and passing it through a 200-mesh sieve for standby.

[0014] Optionally, in step (1), the tool for sample crushing is a pollution-free agate mortar.

[0015] Optionally, in step (2), the working standard is calculated based on 75 μg ± 5 μg of sulfur element.

[0016] Optionally, in step (3), the temperature of the reaction furnace is 1030 °C.

[0017] Optionally, in step (4), the column temperature of the separation column is 90 °C.

[0018] Optionally, during the determination in step (5), an internal standard Ag2S needs to be added to control the data accuracy.

[0019] Optionally, during the determination in step (5), the measured samples are at least determined in parallel 2 times.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] The present invention uses EA-IRMS to analyze sulfur isotopes online. Based on δ 34The S judges the position of the sedimentation center, with accurate results and wide applications. This identification method provides working steps and specific indicators for correctly judging the baryte sedimentation center, offers new ideas for the research on baryte sedimentation and mineralization, and provides technical solutions for exploring and discovering hidden sedimentary baryte ore bodies in China, reducing the exploration cost of baryte, and solving the problem of bottleneck in baryte resources. Description of the Drawings

[0022] Figure 1 It is the ore body distribution map of the Zhenning-Ziyun Devonian baryte ore deposit;

[0023] Figure 2 It is the variation trend map of sulfur isotope composition of the Zhenning-Ziyun Devonian baryte deposit;

[0024] Figure 3 It is the metallogenic model map of the Zhenning-Ziyun Devonian baryte deposit. Detailed Implementation Modes

[0025] It should be noted that the described embodiments are only part of the embodiments of the present invention, not all of them.

[0026] The present invention will be described in detail below in conjunction with the drawings and embodiments of the present invention.

[0027] Embodiment 1 (Leji Section):

[0028] A method for judging the position of the baryte sedimentation center by using sulfur isotope values in this embodiment specifically includes the following steps:

[0029] (1) Select the Leji baryte deposit section, collect baryte samples such as banded, laminated, brecciated, clastic, massive, etc., and grind them with a pollution-free agate mortar to below 200 mesh;

[0030] (2) Weigh 5 mg of the sample meeting the working standard (calculated based on 75 μg ± 5 μg of sulfur element), wrap it tightly with a special tin capsule, and store it in a desiccator for later use;

[0031] (3) The sample falls into the EA reaction furnace (column temperature is 90 °C) through an automatic sampler and burns instantly;

[0032] (4) Add oxygen during the reaction to help the sample decompose fully, and the product is purged by ammonia and enters the separation column (column temperature 90 °C);

[0033] (5) The separated SO2 enters the IRMS to measure δ 34 S, add an internal standard Ag2S during the analysis process to control the data accuracy, and the measured samples are at least measured in parallel 2 times;

[0034] (6) The δ 34The S value varies between +41.9‰ and +68.4‰, with an average of +59.9‰, δ 34 The S value is relatively high, thus it is determined that the distance from the sedimentation center is relatively close. See Figures 1 - 3 .

[0035] Example 2 (Millimeter Profile):

[0036] A method for judging the position of the barite sedimentation center by using sulfur isotope values in this example specifically includes the following steps:

[0037] (1) Select the millimeter barite deposit profile, take massive barite and barite samples with siliceous bands, and grind them to less than 200 mesh with a pollution-free agate mortar;

[0038] (2) Weigh 5 mg of samples meeting the working standard (calculated based on 75 μg ± 5 μg of sulfur element), wrap them tightly with a special tin capsule, and store them in a desiccator for later use;

[0039] (3) The sample falls into the EA reaction furnace (column temperature is 90 °C) through an automatic sampler and burns instantaneously;

[0040] (4) Add oxygen during the reaction to assist the full decomposition of the sample, and the product is purged by ammonia and enters the separation column (column temperature 90 °C);

[0041] (5) The separated SO2 enters the IRMS to measure δ 34 S, and an internal standard Ag2S is added during the analysis process to control the data accuracy. The samples to be measured are at least determined in parallel 2 times;

[0042] (6) The δ 34 S value of the millimeter profile barite, except for the sample ZM13 (δ 34 The S value is +63.3‰), varies between +41.3‰ and +47.0‰, with an average of +43.9‰, δ 34 The S value is medium, thus it is determined that the distance from the sedimentation center is moderate. See Figures 1 - 3 .

[0043] Example 3 (Luocheng Profile):

[0044] A method for judging the position of the barite sedimentation center by using sulfur isotope values in this example specifically includes the following steps:

[0045] (1) Select the Luocheng barite deposit profile, take massive, laminated, and striped barite samples, and grind them to less than 200 mesh with a pollution-free agate mortar;

[0046] (2) Weigh 5 mg of samples meeting the working standard (calculated based on 75 μg ± 5 μg of sulfur element), wrap them tightly with a special tin capsule, and store them in a desiccator for later use;

[0047] (3) The sample falls into the EA reaction furnace (column temperature is 90 °C) through the auto-sampler and burns instantly;

[0048] (4) During the reaction process, oxygen is added to assist the full decomposition of the sample, and the products are purged by ammonia and enter the separation column (column temperature 90 °C);

[0049] (5) The separated SO2 enters the IRMS for δ 34 S determination. During the analysis process, an internal standard Ag2S is added to control the data accuracy, and the samples to be measured are at least determined in parallel 2 times;

[0050] (6) The δ 34 S value of barite in the Luocheng section varies between +27.6‰ and +36.4‰, with an average of +32.7‰. The δ 34 S value is relatively low, from which it is determined that the distance from the deposition center is relatively far. See Figures 1 - 3 .

[0051] Working principle: The sulfur isotope value of the Zhenning-Ziyun Devonian barite deposit is abnormally high, mainly related to the sulfate reduction under the action of bacteria. From Leji to the area of Mohao and Luocheng, the δ 34 S value of barite shows a gradually decreasing trend, which is mainly related to the rapid decrease in the number of microbial bacteria and the more open environment. The sulfur isotope analysis results of the Zhenning-Ziyun Devonian barite deposit are shown in Table 1.

[0052] Table 1. Sulfur isotope analysis results of the Zhenning-Ziyun Devonian barite deposit

[0053]

[0054] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claimed rights.

Claims

1. Application of a method for judging the position of barite deposition center by using sulfur isotope values, characterized in that: Including the following steps: (1) Select barite ore deposits exposed on the surface within the ore-forming area and barite samples from existing drill holes, and conduct crushing and pretreatment of the samples; (2) Weigh 5 mg of samples that meet the working standards, tightly wrap them with special tin capsules, and store them in a desiccator for future use; (3) The samples fall into the EA reaction furnace through an automatic sampler and burn instantaneously; (4) During the reaction, oxygen is added to assist the full decomposition of the samples, and the products are purged by ammonia and enter the separation column; (5)The separated SO2 is subjected to IRMS for δ 34 S determination; (6) Based on δ 34 the S value, determine the position of the deposition center: δ 34 The S value varies between +41.9‰ and +68.4‰, with an average of +59.9‰, δ 34 The S value is relatively high, thus it is determined that the distance from the sedimentation center is relatively close; δ 34 The S value varies between +41.3‰ and +47.0‰, with an average of +43.9‰, δ 34 The S value is medium, thus it is determined that the distance from the sedimentation center is moderate; δ 34 The S value varies between +27.6‰ and +36.4‰, with an average of +32.7‰, δ 34 The S value is relatively low, thus it is determined that the distance from the sedimentation center is relatively far; In the pretreatment of barite sample crushing in step (1), it includes crushing massive barite, grinding it into powder, and passing it through a 200-mesh sieve for standby; In step (1), the tool for sample crushing is a pollution-free agate mortar; In step (2), the working standard is based on 75 μg ± 5 μg of sulfur element; In step (3), the temperature of the reaction furnace is 1030 °C; In step (4), the column temperature of the separation column is 90 °C; During the determination process in step (5), an internal standard Ag2S needs to be added to control the data accuracy.

2. Application of a method for determining the baryte deposition center position by using sulfur isotope values according to claim 1, characterized in that: During the determination process in step (5), the samples to be measured are at least determined in parallel 2 times.

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