CN110737973A - Judgment method of large-scale activity time and stage of hydrothermal fluid in sandstone-type uranium mining area - Google Patents

Abstract

The invention belongs to the technical field of uranium ore, and specifically relates to a method for judging the time and stage of large-scale thermal fluid activity in a sandstone-type uranium mining area. Rich ore samples and non-ore samples; Step S2: Use the rich ore samples for the formulation of fluid inclusion sheets, and the non-ore samples for the selection of heavy mineral apatite; Step S3: On the basis of the fine observation and research of the fluid inclusion sheets, Complete the temperature measurement of the fluid inclusion sheet, and comprehensively analyze the homogeneous temperature data to obtain the homogeneous temperature peak; Step S4: invert the thermal evolution history of the ore-bearing layer in the sandstone-type uranium mining area through the apatite fission track; Step S5: convert the The uniform temperature peak value obtained in step S3 is projected onto the thermal evolution history of the ore-bearing layer obtained in step S4, so as to indirectly determine the time and stage of large-scale activity of thermal fluid in the sandstone-type uranium mining area.

Description

Judgment method of large-scale activity time and stage of hydrothermal fluid in sandstone-type uranium mining area

technical field

The invention belongs to the technical field of uranium mines, and in particular relates to a method for judging the large-scale activity time and stage of thermal fluid in a sandstone-type uranium mine area.

Background technique

In recent years, with the in-depth exploration and research of sandstone-type uranium deposits at home and abroad, more and more uranium geologists have found that Meso-Cenozoic Meso-basic volcanic rocks are developed in the basin or at the margin of the basin, and the surrounding areas are developed Most of the sandstone-type uranium deposits (Kazakhstan, Uzbekistan, Russia, Ordos Basin, Songliao Basin, Erlian Basin, Bayingobi Basin) show strong thermal fluid transformation characteristics, such as hydrothermal erosion of sandstone-type uranium deposits. The uranium mineral type is generally developed, the uranium mineral type has hydrothermal origin, and the ore-forming fluid has the characteristics of medium-low temperature hydrothermal, which reflects that the thermal fluid activity has a strong superimposed transformation effect on the uranium metallogenic process. It is generally known that different thermal fluid activity times (before, during and after uranium mineralization) in sandstone-type uranium deposits have obvious differences in the process of uranium mineralization. The age of the hydrothermal fluid can be estimated by the age of the basic volcanic rock or the structural thermal evolution of the ore-bearing layer. However, when the hydrothermal fluid migrated to the sandstone-type uranium ore-bearing layer and acted on the uranium metallogenic process has not been solved. At the same time, it also affects the further accurate evaluation of the relationship between thermal fluid activity and uranium mineralization in uranium-producing basins.

Based on the above analysis, the sandstone-type uranium deposit field urgently needs a technology to determine the time and stage of large-scale hydrothermal fluid activity, and then to evaluate the relationship between hydrothermal fluid activity and uranium mineralization in uranium-producing basins.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method for judging the large-scale activity time and stage of thermal fluid in sandstone-type uranium mining areas, which is used to solve the problem that in the prior art, it is impossible to judge when the thermal fluid migrates to the sandstone-type uranium mine ore-bearing layer, and the effect of technical issues in the uranium mineralization process.

The technical scheme of the present invention is as follows:

A method for judging the time and stage of large-scale thermal fluid activity in sandstone-type uranium mining areas, the method specifically includes the following steps:

Step S1: collecting sandstone samples of ore-bearing layers in the sandstone-type uranium mining area, including rich ore samples and ore-free samples;

Step S2: the rich ore sample is used for the formulation of fluid inclusion sheets, and the non-ore sample is used for the selection of heavy mineral apatite;

Step S3: On the basis of the fine observation and research of the fluid inclusion sheet, the temperature measurement of the fluid inclusion sheet is completed, and the uniform temperature data is comprehensively analyzed to obtain a uniform temperature peak value;

Step S4: inverting the thermal evolution history of the ore-bearing layer in the sandstone-type uranium mining area through apatite fission track;

Step S5: Project the uniform temperature peak value obtained in step S3 onto the thermal evolution history of the ore-bearing layer obtained in step S4, thereby indirectly judging the large-scale activity time and stage of thermal fluid in the sandstone-type uranium mining area.

The detailed study of the fluid inclusion sheet in the step S3 includes: finding out the genetic age of the inclusions through the study of fluid inclusion schist facies and microbeam fluorescence spectroscopy, and selecting an appropriate inclusion group to complete the measurement of the uniform temperature. Statistical analysis of the data to determine the statistical peak temperatures of inclusions of different generations.

The research on the thermal evolution history of the ore-bearing layer in the sandstone-type uranium mining area in the step S4 includes: applying the theory and method of low-temperature thermochronology, combined with the analysis of the regional structural evolution of the sandstone-type uranium mining area, and using HeFTy software to invert the ore-bearing layer in the uranium mining area. thermal evolution history.

The step S5 also includes: comprehensively studying the large-scale activity time and stage of the obtained thermal fluid in the sandstone-type uranium mining area, the tectonic movement of the sandstone-type uranium mining area, and the volcanic rocks developed around and inside, and verifying the measured large-scale thermal fluid. Accuracy of activity time and session.

In the step S1, the rich ore sample is massive coarse sandstone, the size of the rich ore sample is 3cm×6cm×9cm, the ore-free sample is coarse sandstone-gravel-bearing coarse sandstone, and the weight of the ore-free sample is 5Kg-10Kg.

The step S2 also includes: using 502 cementation to grind the rich ore sample into a fluid inclusion sheet; the non-ore sample is subjected to coarse crushing, fine crushing, screening, elutriation, magnetic separation, heavy liquid separation process, and then under the binocular lens. Apatite single mineral was selected, and the number of apatite single mineral was more than 100 grains. .

The temperature of the thermal fluid is a fluid >75°C.

The beneficial effects of the present invention are:

The method for judging the large-scale activity time and stage of thermal fluid in sandstone-type uranium mining areas designed by the invention covers the process from field geological observation and sampling to indoor experiments and data analysis. The test requirements are clear and the operability is strong.

The method of the invention is extended from the traditional method of indirect dating of fluid inclusions. It not only inherits the advantages of the traditional method of indirect dating of fluid inclusions, but also directly carries out temperature measurement and comprehensive analysis of inclusions and phosphorus in ore-bearing sandstone by improving the Limestone Fission Track (AFT) thermal history simulation is used to finely determine the time and stage of large-scale hydrothermal fluid activity, which can be used to accurately evaluate the superimposed transformation of hydrothermal fluid activity and uranium mineralization in sandstone-type uranium deposits, and complement and improve sandstone-type uranium deposits. The theory has great theoretical significance, has practical significance for the positioning of deep uranium deposits and the expansion of uranium resources, and provides clues and ideas for the research and exploration of deep sandstone-type uranium deposits in various basins in northern China, and has guiding significance.

Description of drawings

Fig. 1 is the flow chart of the method for judging the large-scale activity time and stage of thermal fluid in the sandstone-type uranium mining area designed by the present invention;

Fig. 2 is the homogeneous temperature and comprehensive analysis diagram of sandstone fluid inclusions in the sandstone-type uranium ore-bearing layer of the Ordos Basin in the embodiment of the present invention;

Fig. 3 is the simulation result diagram of apatite fission track temperature-time in the sandstone of the ore-bearing layer of the Ordos Basin sandstone-type uranium ore in the embodiment of the present invention and the large-scale activity time and phase diagram of hydrothermal fluid;

Detailed ways

The following describes in detail the method for judging the large-scale activity time and stage of the thermal fluid in the sandstone-type uranium mining area designed by the present invention with reference to the accompanying drawings and examples.

A method for judging the time and stage of large-scale activity of thermal fluid in a sandstone-type uranium mining area, the method specifically comprises the following steps:

Step S1: collecting sandstone samples of ore-bearing layers in the sandstone-type uranium mining area, including rich ore samples and non-ore samples;

Step S2: the rich ore sample is used for the formulation of fluid inclusion sheets, and the non-ore sample is used for the selection of heavy mineral apatite;

Step S3: On the basis of the fine observation and research of the fluid inclusion sheet, the temperature measurement of the fluid inclusion sheet is completed, and the uniform temperature data is comprehensively analyzed to obtain a uniform temperature peak value;

Step S4: inverting the thermal evolution history of the ore-bearing layer in the sandstone-type uranium mining area through apatite fission track;

Step S5: Project the uniform temperature peak value obtained in step S3 onto the thermal evolution history of the ore-bearing layer obtained in step S4, thereby indirectly judging the large-scale activity time and stage of thermal fluid in the sandstone-type uranium mining area.

The detailed study of the fluid inclusion sheet in the step S3 includes: finding out the genetic age of the inclusions through the study of fluid inclusion schist facies and microbeam fluorescence spectroscopy, and selecting an appropriate inclusion group to complete the measurement of the uniform temperature. Statistical analysis of the data to determine the statistical peak temperatures of inclusions of different generations.

The research on the thermal evolution history of the ore-bearing layer in the sandstone-type uranium mining area in the step S4 includes: applying the theory and method of low-temperature thermochronology, combined with the analysis of the regional structural evolution of the sandstone-type uranium mining area, and using HeFTy software to invert the ore-bearing layer in the uranium mining area. thermal evolution history.

The step S5 also includes: comprehensively studying the large-scale activity time and stage of the obtained thermal fluid in the sandstone-type uranium mining area, the tectonic movement of the sandstone-type uranium mining area, and the volcanic rocks developed around and inside, and verifying the measured large-scale thermal fluid. Accuracy of activity time and session.

In the step S1, the rich ore sample is massive coarse sandstone, the size of the rich ore sample is 3cm×6cm×9cm, the ore-free sample is coarse sandstone-gravel-bearing coarse sandstone, and the weight of the ore-free sample is 5Kg-10Kg.

The step S2 also includes: using 502 cementation to grind the rich ore sample into a fluid inclusion sheet; the non-ore sample is subjected to coarse crushing, fine crushing, screening, elutriation, magnetic separation, heavy liquid separation process, and then under the binocular lens. Apatite single mineral was selected, and the number of apatite single mineral was more than 100 grains.

The temperature of the thermal fluid is a fluid >75°C.

As shown in Figure 1, taking the sandstone-type uranium mining area in the northern margin of the Ordos Basin as an example, the method for judging the large-scale activity time and stage of thermal fluid in the sandstone-type uranium mining area designed by the present invention includes field geological observation and sampling to indoor experiments and data analysis. The specific steps are as follows:

(1) Collection of sandstone samples from ore-bearing layers in the sandstone-type uranium mining area in the northern margin of the Ordos Basin

The rich ore samples and ore-free samples were collected from the same borehole and the same horizon in the sandstone-type uranium mining area of the northern margin of the Ordos Basin. Gravel coarse sandstone, the weight of non-ore samples is 5Kg-10Kg;

(2) Sandstone-type uranium mining area in the northern margin of the Ordos Basin

The rich ore samples are used for the formulation of fluid inclusion sheets, and the non-ore samples are used for the selection of apatite single mineral. The rich ore samples are first cemented with 502 to grind the fluid inclusion sheets; , elutriation, magnetic separation, heavy liquid separation process, and then select apatite single mineral under binocular, the number of apatite single mineral > 100;

(3) Temperature measurement and comprehensive analysis of ore-bearing inclusions in the sandstone-type uranium mining area in the northern margin of the Ordos Basin

Through the detailed petrographic study of the fluid inclusion sheet formulated in step 2, the genetic age of the inclusions was identified, and the carbonate cements, quartz secondary enlargements and secondary inclusion groups that cut through the quartz fractures were selected, and the completion of 42 The homogeneous temperature of 323 inclusions was measured for 323 samples, and the homogeneous temperature distribution was between 65 °C and 133 °C. Considering that previous studies believed that the normal temperature that can be achieved by normal burial of the Zhiluo Formation in the Ordos Basin should be around 70 °C and the thermal According to the definition of fluid, the fluid with a paleofluid temperature > 75°C is called a thermal fluid. Through the statistical analysis of the data of uniform temperature, it is believed that there are mainly two stages of large-scale activities of thermal fluid, with temperatures of 80-90°C and 100-120°C, respectively. Figure 2.

(4) Inversion of thermal evolution history of ore-bearing layers in the sandstone-type uranium mining area in the northern margin of the Ordos Basin;

First, the apatite selected in step 2 is subjected to target making, polishing, etching, radiation and mica etching operations, and then the corresponding software is used to complete the apatite spontaneous, induced track statistics, and Dpar length measurement under reflected light. The data was imported into HeFTy software, and finally an optimal temperature-time curve of the fission track was fitted to invert the thermal evolution history of the ore-bearing layer in the sandstone-type uranium mining area in the northern margin of the Ordos Basin, as shown in Figure 3;

(5) Time and period of large-scale activity of hydrothermal fluids in the sandstone-type uranium mining area in the northern margin of the Ordos Basin

The homogeneous temperature peaks of 80-90 °C and 100-120 °C obtained in step 3 are projected onto the thermal evolution history of the ore-bearing target layer obtained in step 4, and it is obtained that there are two large-scale activities of thermal fluids in the sandstone-type uranium mining area in the northern margin of the Ordos Basin. The time is 98Ma-121Ma and 18Ma-10Ma respectively, as shown in Fig. 3, the time is related to the basalt thermal event (126Ma) developed in the Heitougou area of the sandstone-type uranium mining area in the northern margin of Ordos (126Ma) and the basalt intercalation thermal event (22.7Ma) developed in the Dongshanliang area. Ma ~ 10.2Ma), thereby verifying the correctness of the method for judging the time and stage of large-scale hydrothermal fluid activity in the sandstone-type uranium mining area.

Claims (7)

1. The judgment method of the large-scale activity time and stage of thermal fluid in sandstone type uranium mining area is characterized in that specifically comprising the following steps: Step S1: collecting sandstone samples of ore-bearing layers in the sandstone-type uranium mining area, including rich ore samples and non-ore samples; Step S2: the rich ore sample is used for the formulation of fluid inclusion sheets, and the non-ore sample is used for the selection of heavy mineral apatite; Step S3: On the basis of the fine observation and research of the fluid inclusion sheet, the temperature measurement of the fluid inclusion sheet is completed, and the uniform temperature data is comprehensively analyzed to obtain a uniform temperature peak value; Step S4: inverting the thermal evolution history of the ore-bearing layer in the sandstone-type uranium mining area through apatite fission track; Step S5: Project the uniform temperature peak value obtained in step S3 onto the thermal evolution history of the ore-bearing layer obtained in step S4, thereby indirectly judging the large-scale activity time and stage of thermal fluid in the sandstone-type uranium mining area. 2. The method for judging the large-scale activity time and stage of thermal fluid in sandstone-type uranium mining area according to claim 1, is characterized in that, in described step S3, the meticulous study of fluid inclusion sheet comprises: by fluid inclusion schist facies , Microbeam fluorescence spectroscopy to find out the origin of inclusions and select appropriate inclusion groups to complete the determination of uniform temperature, through the statistical analysis of uniform temperature data, to determine the statistical peak temperature of inclusions of different generations. 3. The method for judging the large-scale activity time and stage of thermal fluid in a sandstone-type uranium mining area according to claim 2, wherein: in the step S4, the research on the thermal evolution history of the ore-bearing layer in the sandstone-type uranium mining area includes: applying low-temperature heat Based on the chronological theory and method, combined with the analysis of the regional tectonic evolution of the sandstone-type uranium mining area, HeFTy software was used to invert the thermal evolution history of the ore-bearing layer after the formation of the uranium mining area. 4. the judgment method for the large-scale activity time and stage of thermal fluid in sandstone-type uranium mining area according to claim 3, it is characterized in that: in described step S5, also comprise: by the large-scale activity of thermal fluid in sandstone-type uranium mining area gained The time and stage, the tectonic movement of the sandstone-type uranium mining area, and the volcanic rocks developed around and inside are comprehensively studied to verify the accuracy of the measured large-scale activity time and stage of thermal fluids. 5. The method for judging the large-scale activity time and stage of thermal fluid in a sandstone-type uranium mining area according to claim 4, characterized in that: in the step S1, the rich ore sample is massive coarse sandstone, and the rich ore sample size is 3cm×6cm× 9cm, the ore-free sample is coarse sandstone-gravel-bearing coarse sandstone, and the weight of the ore-free sample is 5Kg-10Kg. 6. The method for judging the large-scale activity time and stage of thermal fluid in sandstone-type uranium mining area according to claim 5, characterized in that: the step S2 also comprises: the rich ore sample uses 50 2 cemented and ground fluid inclusion sheets; Mineral-free samples are subjected to coarse crushing, fine crushing, sieving, panning, magnetic separation, and heavy liquid separation, and then single apatite mineral is selected under binoculars. The number of apatite single mineral is >100. 7 . The method for judging the large-scale activity time and stage of thermal fluid in a sandstone-type uranium mining area according to claim 6 , wherein the temperature of the thermal fluid is a fluid with a temperature of >75° C. 8 .

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