CN109932365A - A method for determining the origin of bleaching alteration zones in sandstone-type uranium deposits and the relationship between uranium mineralization - Google Patents

Abstract

The invention belongs to geological sciences technical fields, and in particular to a kind of sandrock-type uranium deposit bleach alteration band origin cause of formation and uranium mineralization relationship determine method.The present invention determines the distributing position of bleached sandstone the following steps are included: be directed to interlayer oxidation zone type uranium deposit, and its with mineralized layer, oxidized zone and intermediate zone distribution relation；Establish the primary smalt rock of research area's target zone containing mine and bleached sandstone gross feature distinguishing mark；Field study is carried out for geology-geochemistry phenomenon of sandstone bleach alteration band and acquires sample, and rock-mineral determination analysis, Geochemical Parameters analysis, the analysis of fluid inclusion microscopic observation are carried out to sample；Based on the analysis results, determine interlayer oxidation zone sandstone-type uranium deposits bleach alteration with the origin cause of formation and its with the relationship of uranium mineralization.The present invention can efficiently and accurately determine interlayer oxidation zone sandstone-type uranium deposits bleach alteration the band origin cause of formation and uranium mineralization relationship, have important practical significance to instructing interlayer oxidized zone Prospecting Sandstone-type Uranium Deposits and uranium resource to expand.

Description

A method for determining the origin of bleaching alteration zones in sandstone-type uranium deposits and the relationship between uranium mineralization

technical field

The invention belongs to the field of geological science and technology, and particularly relates to a method for determining the genesis of a bleaching alteration zone of a sandstone-type uranium deposit and a uranium mineralization relationship.

Background technique

Sandstone-type uranium deposits in the interlayer oxidation zone in my country (Mengqigur uranium deposit in Yili Basin, Dongsheng uranium deposit in Ordos Basin, Qianjiadian uranium deposit in Songliao Basin, etc.) The Brovoli, West Agda, Yim deposits, etc.) all have bleached sandstone belts. According to the spatial distribution relationship and color characteristics of the alteration zone, the predecessors believed that the post-oxidized yellow or red rock faded into a white rock, and the uranium ore body was mainly controlled by the contact zone of the bleached alteration zone and the primary color sandstone in the deposit. Alteration zones are important prospecting signs.

Therefore, it is urgent to study the genesis of the bleaching-alteration zone of the sandstone-type uranium deposits in the interlayer oxidation zone and the relationship between uranium mineralization.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is: to propose a method, which can efficiently and accurately determine the genesis of the bleaching alteration zone and the relationship of uranium mineralization in the interlayer oxidation zone sandstone type uranium deposit.

The technical scheme of the present invention is as follows:

A method for determining the genesis of bleaching and alteration zones of sandstone-type uranium deposits and the relationship between uranium mineralization, comprising the following steps: Step 1, for interlayer oxidation zone-type uranium deposits, determine the distribution position of bleached sandstone, and its relationship with mineralized layers, oxidized uranium deposits The distribution relationship between the belt and transition zone; step 2, establish the macro-characteristic identification marks of primary color sandstone and bleached sandstone in the ore-bearing target layer of the study area; step 3, conduct field investigation and collect samples for the geological-geochemical phenomenon of the sandstone bleaching and alteration zone, Perform rock and mineral identification analysis, geochemical parameter analysis, and fluid inclusion microscopic observation analysis on the sample; step 4, according to the analysis results of step 3, determine the cause of the bleaching alteration zone of the sandstone-type uranium deposit in the interlayer oxidation zone and its relationship with uranium mineralization Relationship.

As a preferred solution: Step 1 includes the following operations:

Step 1.1, for the bleaching and alteration zone of the interlayer oxidation zone type uranium deposit, determine the spatial distribution of bleached sandstone through literature research and field geological phenomenon observation;

Step 1.2, determine the morphological characteristics of the ore body in the interlayer oxidation zone type uranium ore mineralization, and its relationship with the positional distribution of the oxidation zone and transition zone, and spatially identify the relationship between the bleaching alteration phenomenon and uranium mineralization.

As a preferred solution: Step 2 includes the following operations:

Based on the primary color of sandstone in the ore-bearing target layer in the study area, combined with the characteristics of field geological profiles and borehole sampling results, the macro identification marks of bleached sandstone and primary-color sandstone in the interlayer oxidation zone of the ore-bearing target layer in the study area are determined.

As a preferred solution: Step 3 includes the following operations:

Step 3.1, select typical boreholes in the deposit in the study area for sampling, and select representative bleached sandstone samples, Primary color sandstone samples, mineralized zone sandstone samples;

Step 3.2, carry out rock and mineral identification analysis of hand specimens and optical thin sections on the sample obtained in step 3.1, and determine its structure, mineral composition, and composition characteristics in combination with X-ray diffraction analysis;

Step 3.3, perform XRF geochemical parameter analysis on the samples obtained in step 3.1, and calculate the average value of each geochemical parameter of bleached altered sandstone samples, primary color sandstone samples and mineralized sandstone samples according to the analysis results, and use this as an important The rock geochemical indicators of bleached sandstone, primary color sandstone and mineralized sandstone;

In step 3.4, microscopic observation of fluid inclusions is carried out on the bleached and altered sandstone samples and the mineralized zone sandstone samples to determine the background characteristics of the geological environment causing the mineralization and alteration.

The beneficial effects of the present invention are:

The invention provides a method for determining the origin of the bleaching alteration zone of a sandstone-type uranium deposit and the relationship of uranium mineralization. Through rock and mineral identification analysis, new geochemical analysis, and microscopic observation of fluid inclusions, the interlayer oxidation zone can be determined efficiently and accurately. The genesis of bleaching alteration zone and uranium mineralization relationship of sandstone-type uranium deposits can be applied to the geological exploration of sandstone-type uranium deposits in the interlayer oxidation zone, which is an important reality for guiding the prospecting of sandstone-type uranium deposits in the interlayer oxidation zone and the expansion of uranium resources significance.

Description of drawings

Fig. 1 shows the spatial distribution of bleaching alteration zone and uranium mineralization zone;

Figure 2 is a cross-sectional view of the exploration line of an interlayer oxidation zone-type uranium deposit.

Detailed ways

The genesis of the bleaching alteration zone of a sandstone-type uranium deposit and the method for determining the uranium mineralization relationship of the present invention will be described in detail below with reference to the accompanying drawings and examples.

A method for determining the genesis of the bleaching alteration zone of a sandstone-type uranium deposit and a uranium mineralization relationship of the present embodiment includes the following steps:

Step 1, taking the typical interlayer oxidation zone type uranium deposit as the research object, dissect the distribution position of bleached sandstone, and the distribution relationship between bleached sandstone and mineralization, oxidation zone and transition zone through investigation of literature data and field geological phenomenon observation;

Step 1.1, taking the bleaching alteration zone of the Mengqigur uranium deposit in the Yili Basin, Xinjiang as the research object, and determining the spatial distribution of bleached sandstones through literature research and field geological phenomenon observations;

According to the spatial distribution of the bleached-altered zone and the uranium mineralization zone shown in Figure 1, it is judged that the uranium mineralization on the plane is mainly produced near the fault, and the bleached-altered sandstone and the primary color sandstone (in this example, the primary color sandstone It is the transition part of primary gray sandstone).

Step 1.2, determine the morphological characteristics of the ore body of the interlayer oxidation zone type uranium ore mineralization layer, and the distribution relationship between the mineralization layer and the oxidation zone and transition zone, and identify the relationship between the bleaching alteration phenomenon and the uranium mineralization from the space .

As shown in Fig. 2, vertical uranium mineralization also occurs in the transition zone between bleached-zone sandstone and primary gray sand body near the primary gray sand body, and some ores locally contain more organic matter.

Step 2, establish the macro-characteristic identification marks of primary color sandstone and bleached sandstone in the ore-bearing target layer in the study area;

Step 2.1, based on the primary color of the ore-bearing target sandstone in the study area, combined with the characteristics of field geological profiles and borehole sampling results, to determine the macroscopic identification marks of bleached sandstone and primary color sandstone in the interlayer oxidation zone of the target layer in the study area.

Bleached sandstone mainly refers to the gray-white sandstone with strong cladization, distributed in parallel with the strata, and the lithology is mainly feldspar lithic sandstone or feldspar lithic sandstone. Carbon and pyrite. Primary-colored sandstone is mainly primary phytolithic sandstone with gray or gray-green color.

Step 3, carry out field investigation and systematic sample collection for the geological-geochemical phenomenon of the sandstone bleaching zone, and perform petrological, mineralogical, geochemical and other index analysis on the sample;

Step 3.1, select typical boreholes of the Mengqigur uranium deposit for sampling, and select representative bleached sandstones in each borehole target layer according to the spatial location determined in step 1 and the macro identification criteria established in step 2 Sample, denoted as A; primary color sandstone sample, denoted as B; mineralized zone sample, denoted as C;

Step 3.2, carry out the rock and mineral identification analysis of hand specimens and light thin sections on the samples obtained in 3.1, to determine their structural structure, mineral composition, composition characteristics, etc.;

In step 3.3, the samples obtained in 3.1 are analyzed by XRF and other related parameters of geochemistry, and the average value of each geochemical parameter of bleached altered sandstone, primary color sandstone and mineralized sandstone samples is calculated according to the analysis results, and used as an important bleached sandstone. , rock geochemical indicators of primary color sandstone and mineralized sandstone.

According to the comprehensive analysis of sandstone color, iron mineral characteristics and other chemical indicators, the petrological and geochemical characteristics of bleached sandstone, primary color sandstone and mineralized zone sandstone of interlayer oxidation zone type uranium deposits are as follows:

Table 1 Summary of petrological and geochemical characteristics of bleached sandstone, primary colored sandstone and mineralized sandstone

Bleaching alteration zone: The rocks are mainly grayish white. Poor pyrite, feldspar has strong clayification, and is mainly characterized by strong kaolinite. The content of kaolinite in clay minerals can reach up to 85%, and its average content accounts for 77.27% of the total clay minerals, and the content of organic matter is low.

Mineralized zone: It is the main enrichment zone of uranium minerals. The rocks are gray, gray-black and gray-white. The clay alteration is relatively strong. The average content of kaolinite accounts for 72% of the clay minerals. The quartz has a secondary increase phenomenon under scanning electron microscope. .

Primary color sandstone belt: The rock color is mainly gray and gray-green. The sandstone is basically not subjected to epigenetic modification and alteration, and generally represents the original environment during diagenesis. The organic matter is relatively rich, and the iron minerals include pyrite, magnetite and a small amount of siderite. Fe ³⁺ /Fe ²⁺ is generally low, ranging from 0.2 to 0.4, with an average of 0.39. Clayification of feldspar is more common, see kaolinization and a small amount of chlorite, which should be mainly alteration products during the diagenetic period.

Table 2 Contents of major elements in bleached sandstone and other sandstones in the study area (%)

The analysis and test results show that the w(Al ₂ O ₃ ) in the bleached sandstone belt is significantly increased, indicating that clayization has a certain effect on rock bleaching; while the mass fractions of w(CaO) and w(MgO) are significantly reduced, indicating that the bleached sandstone The decarbonation effect is obvious.

Iron is a common dye in nature, and the mass fraction _of iron oxides is an important geochemical indicator of _{postgenetic alteration} . ₃ ) was significantly reduced, and the w(TFe ₂ O ₃ )/w(TFeO) ratio representing the redox condition was significantly lower than that of the primary colored sandstone, indicating that the bleached sandstone suffered from reductive alteration. The reason may be the acidic geochemical barrier produced during the thermal evolution of organic matter near the redox front where the bleached sandstone is located.

In step 3.4, microscopic observation of fluid inclusions is performed on the bleached altered sandstone and sandstone samples in the mineralization zone to determine the background characteristics of the geological environment causing the mineralization and alteration.

The fluid inclusions used for the observation are mainly distributed in the cracks in the quartz grains, passing through the secondary enlarged edges of the quartz grains and quartz, and their characteristics indicate that they are secondary fluid inclusions, mainly including liquid-rich brine inclusions and hydrocarbon-containing aqueous solutions. Two types of inclusions. Determination by the homogeneous temperature method: the homogeneous temperature range of the inclusions reaching a homogeneous liquid phase is 50-77 °C, concentrated at 62-73 °C, with an average of 66.2 °C, reflecting that the uranium deposit is a low-temperature hydrothermal uranium deposit. The measured salinity of the inclusions spans a wide range, ranging from 1.4 to 14.04% (NaCleq). The salinity is concentrated between 2% and 8%, and the average salinity is 4.49%, reflecting the low salinity of the ore-forming fluid. It shows that the ore-forming fluid has the characteristics of low temperature and low salinity, indicating that the uranium deposit is a low-temperature epigenetic epigenetic uranium deposit. The existence of a large number of hydrocarbon inclusions also indicates that a small amount of oil and gas activities are involved in the reduction and precipitation process of uranium.

In step 4, combined with the data obtained in 3.2, 3.3 and 3.4, comprehensively analyze the genesis of the bleaching alteration zone of the sandstone-type uranium deposit in the interlayer oxidation zone and its relationship with uranium mineralization.

According to the data obtained in 3.2, 3.3 and 3.4, it shows that the uranium-containing oxygenated water oxidizes the primary color sandstone during the interlayer migration process, and Fe ions migrate with the interlayer water, resulting in a decrease in the content of w(TFe ₂ O ₃ ) and a decrease in organic matter. It is oxidized and decomposed, and at the same time, it is accompanied by hydrolysis of feldspar in sandstone to produce kaolinization, etc., resulting in fading and alteration of rock (bleaching alteration zone). With the continuous consumption of oxygen in the interlayer water, the source of deep reducing gas is filled, which makes the composition of the ore-forming fluid continue to acidify, and the Eh value in the environment decreases. The change of factors such as the value of precipitation, aggregation and mineralization.

The invention is suitable for most of the interlayer oxidation zone type sandstone type uranium metallogenic areas in northern my country. By studying the spatial distribution relationship and genetic characteristics of bleaching alteration zones and uranium mineralization in interlayer oxidation zone uranium deposits, due to the obvious color characteristics of bleaching alteration zones under naked eye observation, they can be used as interlayers. The important prospecting marker layer of the oxidation zone type uranium deposit provides an important field identification mark for the geological exploration of the interlayer oxidation zone type sandstone type uranium deposit, and has the characteristics of high efficiency and rapidity.

The above-mentioned embodiments are only the best method combinations of the present invention, but the present invention is not limited to the above-mentioned implementation cases. Within the scope of knowledge possessed by those skilled in the art, other method combinations can be proposed without departing from the spirit of the present invention.

Claims (4)

1. a sandstone type uranium deposit bleaching alteration zone genesis and uranium mineralization relationship determination method, is characterized in that: comprise the following steps: Step 1, for the interlayer oxidation zone type uranium deposit, determine the distribution position of bleached sandstone and its distribution relationship with mineralized layer, oxidation zone and transition zone; Step 2, establish the macro-characteristic identification marks of primary color sandstone and bleached sandstone in the ore-bearing target layer in the study area; Step 3, conduct field investigation and collect samples for the geological-geochemical phenomenon of the sandstone bleaching alteration zone, and perform rock and mineral identification analysis, geochemical parameter analysis, and fluid inclusion microscopic observation and analysis on the samples; Step 4: According to the analysis result of Step 3, determine the cause of bleaching alteration zone of the sandstone-type uranium deposit in the interlayer oxidation zone and its relationship with uranium mineralization. 2. a kind of sandstone type uranium deposit bleaching alteration zone genesis and uranium mineralization relationship determination method according to claim 1, is characterized in that: step 1 comprises the following operations: Step 1.1, for the bleaching and alteration zone of the interlayer oxidation zone type uranium deposit, determine the spatial distribution of bleached sandstone through literature research and field geological phenomenon observation; Step 1.2, determine the morphological characteristics of the ore body in the interlayer oxidation zone type uranium ore mineralization, and its relationship with the positional distribution of the oxidation zone and transition zone, and spatially identify the relationship between the bleaching alteration phenomenon and uranium mineralization. 3. a kind of sandstone type uranium deposit bleaching alteration zone genesis and uranium mineralization relationship determination method according to claim 2, is characterized in that: step 2 comprises the following operations: Based on the primary color of sandstone in the ore-bearing target layer in the study area, combined with the characteristics of field geological profiles and borehole sampling results, the macro identification marks of bleached sandstone and primary-color sandstone in the interlayer oxidation zone of the ore-bearing target layer in the study area are determined. 4. a kind of sandstone type uranium deposit bleaching alteration zone genesis and uranium mineralization relationship determination method according to claim 3, is characterized in that: step 3 comprises the following operations: Step 3.1, select typical boreholes in the deposit in the study area for sampling, and select representative bleached sandstone samples, Primary color sandstone samples, mineralized zone sandstone samples; Step 3.2, carry out rock and mineral identification analysis of hand specimens and optical thin sections on the sample obtained in step 3.1, and determine its structure, mineral composition, and composition characteristics in combination with X-ray diffraction analysis; Step 3.3, perform XRF geochemical parameter analysis on the samples obtained in step 3.1, and calculate the average value of each geochemical parameter of bleached altered sandstone samples, primary color sandstone samples and mineralized sandstone samples according to the analysis results, and use this as an important The rock geochemical indicators of bleached sandstone, primary color sandstone and mineralized sandstone; In step 3.4, microscopic observation of fluid inclusions is carried out on the bleached and altered sandstone samples and the mineralized zone sandstone samples to determine the background characteristics of the geological environment causing the mineralization and alteration.