Method for extracting calcareous microfossil of consolidated sediment

Abstract

The invention discloses a method for extracting calcareous microfossils of consolidated sediments, which comprises the following steps: S1, taking a rock core sample or a rock debris sample of the consolidated sediments, cleaning the surface of the rock core sample or the rock debris sample, and crushing the rock core sample or the rock debris sample to obtain a debris sample; s2, weighing a chipping sample, soaking the chipping sample in water, heating the chipping sample, and then freezing the chipping sample to obtain a frozen sample; s3, hydrogen peroxide is added into the frozen sample and mixed, then sieving and cleaning are conducted, and first particles are obtained; adding a weakly alkaline reagent and heating to obtain a first mixture; s4, adding an anti-flocculating agent into the first mixture, mixing, and carrying out ultrasonic treatment to obtain a second mixture; and then sieving, cleaning, drying and collecting a particle sample. According to the method, more calcareous microfossils are physically separated out, chips adhering to the surfaces of the calcareous microfossils fall off, chemical decomposition of the fossils and adhering particles is promoted, meanwhile, preservation of fossil shells is facilitated, and fine particles are prevented from being flocculated and precipitated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of microfossil extraction, and particularly to a method for extracting calcareous microfossils from consolidated sediments. BACKGROUND

[0002] Microfossil analysis of marine petroleum drilling sediment cores is a key means to reveal the age of the sediment strata. The study of microfossil communities and their fossil shell isotopes and geochemistry is an important way to deeply understand the mechanism of marine oil and gas resource accumulation environment and oil and gas evaluation. And obtaining a large number of high-quality calcareous microfossils is the basis for implementing these scientific researches.

[0003] Loose or semi-consolidated sediments generally use the standard microfossil experimental treatment method, i.e. hydrogen peroxide (H2O2) method. However, due to the consolidation and partial diagenesis of the sediments, the extraction of calcareous microfossils, i.e. foraminifera, from deep-sea drilling cores, especially from cores with large burial depth, is difficult. Moreover, the standard microfossil treatment method usually obtains a small number of foraminifera fossils, and the shell surface is often adhered to and filled with foreign particles. This not only affects the reliability of foraminifera identification, but also makes it impossible to identify the fossils. At the same time, the substances adhered to and filled in the fossil shells have obvious differences in chemical composition from the foraminifera shells, which seriously affects the application of paleoenvironmental research using calcareous microfossil shells in isotopic and geochemical testing techniques. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a method for extracting calcareous microfossils from consolidated sediments.

[0005] The technical solution adopted by the present application to solve the technical problem is: a method for extracting calcareous microfossils from consolidated sediments, comprising the following steps: S1, taking a core sample or a rock sample of consolidated sediments, cleaning the surface and crushing to obtain a crushed sample; S2, weighing the crushed sample, soaking it in water and heating, then freezing to obtain a frozen sample; S3, adding hydrogen peroxide to the frozen sample and mixing, then sieving and washing to obtain a first particulate matter; adding a weakly alkaline reagent and heating to obtain a first mixture; S4, adding an anti-flocculating agent to the first mixture and mixing, and performing ultrasonic treatment to obtain a second mixture; then sieving and washing, drying, and collecting a particulate sample.

[0006] Preferably, in the step S1, the particle size of the crushed sample is less than 3 mm.

[0007] Preferably, in step S2, a detrital sample is weighed according to the abundance of calcareous microfossils, and the content of the detrital sample in water is 0.05~0.2g / mL.

[0008] Preferably, in step S2, the debris sample is soaked in water and heated to boiling for 1.5 to 2.5 hours. During the boiling process, water is added to keep the liquid level constant, and then the sample is frozen at -25°C to -15°C until it freezes.

[0009] Preferably, in step S3, 1-5% hydrogen peroxide is added to the frozen sample, mixed, and allowed to stand for 20-28 hours, then passed through a 45-90μm sieve and washed with water; the volume ratio of the frozen sample to hydrogen peroxide is 1:(1-2).

[0010] Preferably, in step S3, a weak alkaline reagent is added to the first particulate matter and heated to boiling for 1.5 to 2.5 hours. Water is added during the boiling process to keep the liquid level constant, and the mixture is allowed to stand for 20 to 28 hours after cooling.

[0011] Preferably, in step S3, the weak alkaline reagent is a sodium bicarbonate solution with a concentration of 0.05~0.2 g / mL, and the content of the first particulate matter in the weak alkaline reagent is 0.05~0.15 g / mL.

[0012] Preferably, in step S4, an anti-flocculation agent is added to the first mixture, and after mixing, the mixture is allowed to stand for 0.5 to 1.5 hours, and then ultrasonically treated at a frequency of 30 to 50 kHz for 0.5 to 1.5 minutes.

[0013] Preferably, in step S4, the antiflocculation agent is a 0.3~0.7% sodium hexametaphosphate solution, and the volume ratio of the antiflocculation agent to the first mixture is (0.5~2):100.

[0014] Preferably, in step S4, the second mixture is passed through a 45-90 μm sieve and washed with water, and the resulting second particulate matter is dried at 50-70°C.

[0015] The beneficial effects of this invention are as follows: The method for extracting calcareous microfossils from consolidated sediments involves pulverizing the consolidated sediment sample, soaking it in water, heating it, and then freezing it, which allows for the physical separation of more calcareous microfossils and the shedding of adhering debris from their surface. Treatment with hydrogen peroxide and a weakly alkaline reagent decomposes the organic matter in the sample, promoting the chemical decomposition of fossils and adhering particles, while also facilitating the preservation of the fossil shell. The addition of an anti-flocculation agent and ultrasonic treatment prevents the flocculation and sedimentation of fine particles, thus promoting particle dispersion. Attached Figure Description

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings: Figure 1 This is a flowchart of the method for extracting calcareous microfossils from consolidated sediments according to the present invention; Figure 2 This is a microscopic image of the benthic foraminifera obtained from the treatment in Comparative Example 1. Figure 3 This is a microscopic observation of the benthic foraminifera obtained in Example 1. Figure 4 The image shows a microscopic observation of the planktonic foraminifera obtained from the treatment in Comparative Example 1. Figure 5 This is a microscopic image of the planktonic foraminifera obtained in Example 1. Figure 6 This is a microscopic observation of a portion of the shell surface of a benthic foraminifera obtained from the treatment in Comparative Example 1. Figure 7 This is a partial microscopic observation of the shell surface of a benthic foraminifera obtained from the treatment in Example 1. Figure 8 This is a partial microscopic observation of the shell surface of a planktonic foraminifera obtained from the treatment in Comparative Example 1. Figure 9 This is a partial microscopic observation of the shell surface of a planktonic foraminifera obtained through the treatment in Example 1. Detailed Implementation

[0017] To provide a clearer understanding of the technical features, objectives, and effects of this invention, the invention will be further described in detail below with reference to embodiments. These embodiments are only used to explain the invention and do not constitute a limitation on the scope of protection of this invention.

[0018] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0019] This invention proposes a method for extracting calcareous microfossils from consolidated sediments, such as... Figure 1 As shown, the extraction method includes the following steps: S1. Take core samples or rock fragment samples of consolidated sediments, clean the surface and crush them to obtain fragment samples.

[0020] Surface cleaning involves thoroughly cleaning the core or rock fragment samples until the surface is free of dust. For rock fragment samples, larger fragments should be selected whenever possible. Crushing can be done by gently tapping the core or rock fragment samples with a hammer, resulting in fragments with a particle size less than 3 mm. The particle size of the fragments can be less than 3 mm or even less than 2 mm; the specific particle size is not limited. Note that when crushing each sample, a new sheet of kraft paper or A4 copy paper should be placed on a stainless steel or aluminum alloy plate to prevent potential contamination between samples.

[0021] S2. Weigh the debris sample, soak it in water and heat it, then freeze it to obtain a frozen sample.

[0022] Based on the abundance of calcareous microfossils, and specifically based on the properties of the main sediments combined with observations of existing thin sections (core / well wall core rock thin sections), determine the appropriate sample amount, and then weigh the detrital sample (e.g., using an electronic balance). The sample amount should be 10-50 grams, such as 10 grams, 20 grams, 30 grams, 40 grams, or 50 grams, with 15-25 grams being optimal.

[0023] Further, the debris sample is soaked in water and heated to boiling for 1.5 to 2.5 hours, with water added during boiling to maintain a constant liquid level. It is then frozen at -25°C to -15°C until solid. The boiling time can be 1.5 hours, 2 hours, or 2.5 hours, and the freezing temperature can be -25°C, -20°C, or -15°C.

[0024] Specifically, slowly pour the fragmentary sample into a container (such as a stainless steel basin or ceramic crucible), taking care to avoid rapid pouring which could cause fine particles to float into the air, resulting in sample contamination and loss. Then add water and heat the container on a hot plate until it boils. During boiling, add water as needed based on the liquid level to maintain a constant liquid level and prevent the container from drying out. After boiling, cool and then freeze (e.g., in a freezer) until it is completely frozen. In this way, the water that has been boiled permeates the fragmentary sample, and the expansion of the water upon freezing allows more calcareous microfossils (such as foraminifera fossils) to separate (physically), and the debris adhering to the fossil surface falls off.

[0025] The concentration of the debris sample in water is 0.05~0.2 g / mL, such as 0.05 g / mL, 0.1 g / mL, 0.15 g / mL, or 0.2 g / mL. For example, if 20 g of debris sample is weighed and 200 mL of water is added, the concentration of the debris sample in water is 0.1 g / mL.

[0026] S3. Add hydrogen peroxide to the frozen sample and mix, then sieve and wash to obtain the first particulate matter; add a weak alkaline reagent and heat to obtain the first mixture.

[0027] Add 1-5% hydrogen peroxide to the frozen sample, mix, and let stand for 20-28 hours, such as 20, 22, 24, 26, or 28 hours. The volume ratio of frozen sample to hydrogen peroxide is 1:(1-2), which can be 1:1, 1:1.3, 1:1.5, or 1:2, etc. Specifically, place the frozen sample at room temperature, add hydrogen peroxide (add slowly to avoid violent reaction), gently shake and mix thoroughly, and shake once more during the standing process. When the sediment settles and the water becomes clear, shake again to suspend the sediment.

[0028] For samples with high organic matter content, the hydrogen peroxide treatment step needs to be repeated appropriately. The organic matter content can be judged by the intensity of the reaction (the rate of bubble generation). High organic matter content means that a large number of bubbles are generated after adding hydrogen peroxide, such as bubbles still being generated after standing for 24 hours. In this case, the hydrogen peroxide treatment step needs to be repeated until very few bubbles are generated. Hydrogen peroxide decomposes the organic matter in the sample, thereby dispersing the sample particles.

[0029] Further, the settled reaction mixture is passed through a 45-90 μm sieve and washed with water. Specifically, the mixture is sieved under tap water to wash away fine particulate components. The particles on the sieve are then transferred to a new container (such as a stainless steel bowl or a ceramic crucible) to obtain the first particulate matter. The sieve aperture can be 45 μm, 53 μm, 63 μm, 75 μm, or 90 μm, etc.

[0030] Furthermore, a weakly alkaline reagent is added to the first particulate matter and heated to boiling. The mixture is boiled for 1.5 to 2.5 hours, with water added during boiling to maintain a constant liquid level. After cooling, it is allowed to stand for 20 to 28 hours to obtain the first mixture. The boiling time can be 1.5 hours, 2 hours, or 2.5 hours, and the standing time can be 20 hours, 22 hours, 24 hours, 26 hours, or 28 hours. Specifically, a weakly alkaline reagent is added to a container containing the first particulate matter, and then the container is placed on a hot plate and heated to boiling. During boiling, water needs to be added as needed based on changes in the liquid level to maintain a constant liquid level and prevent the mixture from drying out.

[0031] Preferably, the weakly alkaline reagent is a sodium bicarbonate solution with a concentration of 0.05~0.2 g / mL, which can be 0.05 g / mL, 0.1 g / mL, 0.15 g / mL, or 0.2 g / mL, etc.; the content of the first particulate matter in the weakly alkaline reagent is 0.05~0.15 g / mL, which can be 0.05 g / mL, 0.1 g / mL, or 0.15 g / mL, etc. The sodium bicarbonate solution can be formed by mixing a certain amount of water and sodium bicarbonate (NaHCO3) in a container. For example, 200 mL of water and 20 g of sodium bicarbonate are added to a container containing the first particulate matter, and the sodium bicarbonate solution with a concentration of 0.1 g / mL is formed after the sodium bicarbonate is fully dissolved. The weakly alkaline reagent is beneficial for the preservation and insolubility of the calcium carbonate shell of calcareous microfossils (such as foraminifera), while also promoting the chemical decomposition of foraminifera and attached particles.

[0032] S4. Add anti-flocculation agent to the first mixture and mix, then perform ultrasonic treatment to obtain the second mixture; then sieve, wash, dry, and collect particulate samples.

[0033] An antiflocculation agent is added to the first mixture, and after mixing, it is allowed to stand for 0.5 to 1.5 hours, followed by ultrasonic treatment at a frequency of 30 to 50 kHz for 0.5 to 1.5 minutes. The standing time can be 0.5 hours, 1 hour, or 1.5 hours, the ultrasonic frequency can be 30 kHz, 35 kHz, 40 kHz, 45 kHz, or 50 kHz, and the ultrasonic time can be 0.5 minutes, 1 minute, or 1.5 minutes. Specifically, an antiflocculation agent is added to the first mixture to prevent fine particles from flocculating and settling. After gently shaking and mixing, it is allowed to stand, and then placed in an ultrasonic cleaner for ultrasonic vibration cleaning to obtain a second mixture. The antiflocculation agent is a 0.3 to 0.7% sodium hexametaphosphate solution, and the volume ratio of the antiflocculation agent to the first mixture is (0.5 to 2):100, such as 0.5:100, 1:100, 1.5:100, or 2:100.

[0034] Further, the second mixture is passed through a 45-90 μm sieve and washed with water. The resulting second particulate matter is then dried at 50-70°C. The sieve aperture can be 45 μm, 53 μm, 63 μm, 75 μm, or 90 μm, and the drying temperature can be 50°C, 55°C, 60°C, 65°C, or 70°C. Specifically, the mixture is passed through a sieve under tap water, rinsed until the water is clear, and the coarse particles on the sieve are transferred to filter paper. The resulting second particulate matter is then dried in an oven. The particulate samples are then collected, weighed, packaged, and the sample information is recorded before storage. The particulate samples include calcareous microfossils and other coarse-grained rock fragments and minerals. The calcareous microfossils mainly include foraminifera fossils, and also include a small amount of other fossils.

[0035] The present invention discloses a method for extracting calcareous microfossils from consolidated sediments. After crushing the consolidated sediment sample, the sample is soaked in water, heated, and then frozen to allow more calcareous microfossils to be physically separated, and the debris adhering to the surface falls off. Hydrogen peroxide and a weak alkaline reagent are added to decompose the organic matter in the sample, promote the chemical decomposition of fossils and attached particles, and facilitate the preservation of the fossil shell. An anti-flocculation agent is added and ultrasonic treatment is performed to prevent fine particles from flocculating and settling, which is beneficial to particle dispersion.

[0036] The following is an illustration through specific examples: Example 1 A method for extracting calcareous microfossils from consolidated sediments, comprising the following steps: S1. Take core samples of consolidated sediments, clean the surface and crush them to obtain debris samples.

[0037] Specifically, the core sample is cleaned until the surface is free of dust, and then the core sample is gently tapped with a hammer to obtain a fragment sample with a particle size of less than 2 mm.

[0038] S2. Weigh the debris sample, soak it in water and heat it, then freeze it to obtain a frozen sample.

[0039] Specifically, weigh 20 grams of debris sample, add 200 mL of water to soak the debris sample and heat to boiling, boil for 2 hours, add water during boiling to keep the liquid level constant, and then freeze at -20℃ until frozen.

[0040] S3. Add hydrogen peroxide to the frozen sample and mix, then sieve and wash to obtain the first particulate matter; add a weak alkaline reagent and heat to obtain the first mixture.

[0041] Specifically, the frozen sample was placed at room temperature, and 225 mL of 3% hydrogen peroxide was slowly added. After mixing, it was allowed to stand for 24 hours. Then, it was passed through a 63 μm standard sieve and washed with water. 200 mL of water and 20 g of baking soda were added to the first particulate matter to form a baking soda solution (weakly alkaline reagent) with a concentration of 0.1 g / mL. The solution was heated to boiling and boiled for 2 hours. During the boiling process, water was added to keep the liquid level constant. After cooling, it was allowed to stand for 24 hours.

[0042] S4. Add anti-flocculation agent to the first mixture and mix, then perform ultrasonic treatment to obtain the second mixture; then sieve, wash, dry, and collect particulate samples.

[0043] Specifically, 2 mL of 0.5% sodium hexametaphosphate solution (anti-flocculation agent) was added to the first mixture, and after mixing, it was allowed to stand for 1 hour, followed by ultrasonic treatment at a frequency of 40 kHz for 1 minute. The resulting second mixture was passed through a 63 μm standard sieve and washed with water until the water was clear. The resulting second particulate matter was dried at 60 °C. The particulate samples were collected, weighed, packaged, and the sample information was recorded before storage. The particulate samples included calcareous microfossils such as foraminifera and other coarse-grained rock fragments and minerals.

[0044] Example 2 A method for extracting calcareous microfossils from consolidated sediments, comprising the following steps: S1. Take rock fragment samples from the consolidated sediments, clean the surface and crush them to obtain fragment samples.

[0045] Specifically, take a larger rock chip sample, clean it until the surface is free of dust, and then gently tap the rock chip sample with a hammer to obtain a fragment sample with a particle size of less than 3 mm.

[0046] S2. Weigh the debris sample, soak it in water and heat it, then freeze it to obtain a frozen sample.

[0047] Specifically, weigh 25 grams of debris sample, add 180 mL of water to soak the debris sample and heat to boiling, boil for 2.5 hours, add water during boiling to keep the liquid level constant, and then freeze at -25°C until frozen.

[0048] S3. Add hydrogen peroxide to the frozen sample and mix, then sieve and wash to obtain the first particulate matter; add a weak alkaline reagent and heat to obtain the first mixture.

[0049] Specifically, the frozen sample was placed at room temperature, and 200 mL of 5% hydrogen peroxide was slowly added. After mixing, the sample was allowed to stand for 28 hours. Then, it was passed through a 75 μm standard sieve and washed with water. 300 mL of water and 40 g of baking soda were added to the first particulate matter to form a baking soda solution (weakly alkaline reagent) with a concentration of 0.13 g / mL. The solution was heated to boiling and boiled for 2.5 hours. During the boiling process, water was added to keep the liquid level constant. After cooling, the sample was allowed to stand for 28 hours.

[0050] S4. Add anti-flocculation agent to the first mixture and mix, then perform ultrasonic treatment to obtain the second mixture; then sieve, wash, dry, and collect particulate samples.

[0051] Specifically, 3 mL of 0.7% sodium hexametaphosphate solution (anti-flocculation agent) was added to the first mixture, and after mixing, it was allowed to stand for 1.5 hours. Then, it was ultrasonically treated at a frequency of 50 kHz for 1 minute. The resulting second mixture was passed through a 75 μm standard sieve and washed with water until the water was clear. The resulting second particulate matter was dried at 70 °C. The particulate samples were collected, weighed, packaged, and the sample information was recorded before storage. The particulate samples included calcareous microfossils such as foraminifera and other coarse-grained rock fragments and minerals.

[0052] Example 3 A method for extracting calcareous microfossils from consolidated sediments, comprising the following steps: S1. Take core samples of consolidated sediments, clean the surface and crush them to obtain debris samples.

[0053] Specifically, the core sample is cleaned until the surface is free of dust, and then the core sample is gently tapped with a hammer to obtain a fragment sample with a particle size of less than 3 mm.

[0054] S2. Weigh the debris sample, soak it in water and heat it, then freeze it to obtain a frozen sample.

[0055] Specifically, weigh 15 grams of debris sample, add 200 mL of water to soak the debris sample and heat to boiling, boil for 1.5 hours, add water during boiling to keep the liquid level constant, and then freeze at -15°C until frozen.

[0056] S3. Add hydrogen peroxide to the frozen sample and mix, then sieve and wash to obtain the first particulate matter; add a weak alkaline reagent and heat to obtain the first mixture.

[0057] Specifically, the frozen sample was placed at room temperature, and 250 mL of 2% hydrogen peroxide was slowly added. After mixing, the sample was allowed to stand for 20 hours. Then, it was passed through a 53 μm standard sieve and washed with water. 200 mL of water and 15 g of baking soda were added to the first particulate matter to form a baking soda solution (weakly alkaline reagent) with a concentration of 0.075 g / mL. The solution was heated to boiling and boiled for 1.5 hours. During the boiling process, water was added to keep the liquid level constant. After cooling, the sample was allowed to stand for 20 hours.

[0058] S4. Add anti-flocculation agent to the first mixture and mix, then perform ultrasonic treatment to obtain the second mixture; then sieve, wash, dry, and collect particulate samples.

[0059] Specifically, 1.5 mL of 0.3% sodium hexametaphosphate solution (anti-flocculation agent) was added to the first mixture, and after mixing, it was allowed to stand for 0.5 hours. Then, it was ultrasonically treated at a frequency of 30 kHz for 1.5 minutes. The resulting second mixture was passed through a 50 μm standard sieve and washed with water until the water was clear. The resulting second particulate matter was dried at 50 °C. The particulate samples were collected, weighed, packaged, and the sample information was recorded and stored. The particulate samples included calcareous microfossils such as foraminifera and other coarse-grained rock fragments and minerals.

[0060] Comparative Example 1 This comparative example is a standard micropaleontological hydrogen peroxide method. The difference between this example and Example 1 is that the S2 and S3 steps of the present invention, the addition of a weak alkaline reagent, the addition of an anti-flocculation agent, and the ultrasonic treatment in the S4 step of Example 1 were not performed.

[0061] Specifically, the hydrogen peroxide method in this comparative example includes the following steps: R1. Take a core sample of the consolidated sediment, clean its surface and crush it to obtain a fragment sample.

[0062] Specifically, the core sample is cleaned until the surface is free of dust, and then the core sample is gently tapped with a hammer to obtain a fragment sample with a particle size of less than 2 mm.

[0063] R2. Add hydrogen peroxide to the debris sample and mix, then sieve and wash to obtain particulate matter.

[0064] Specifically, 200 mL of 3% hydrogen peroxide was slowly added to a 20 g debris sample, mixed, and allowed to stand for 24 hours. The mixture was then passed through a 63 μm standard sieve and washed with water to obtain particulate matter.

[0065] R3. Dry the particulate matter and collect the particulate sample.

[0066] Specifically, the particulate matter was dried at 60°C, and the particulate samples were collected, weighed, packaged, and the sample information was recorded before storage. The particulate samples included calcareous microfossils such as foraminifera and other coarse-grained rock fragments and minerals.

[0067] Comparative experiment: Core samples from the 2929m stratum of well L4 in the Baiyun Depression of the Pearl River Mouth Basin in the northern South China Sea shelf were processed using both the hydrogen peroxide method (Method A) of Comparative Example 1 and the extraction method of Example 1 of this invention (Method B), yielding particle sample A and particle sample B. Both particle samples were passed through a 150μm standard sieve and dried. The particles remaining on the sieve were observed under a stereomicroscope, and the number of calcareous microfossil foraminifera was selected and counted to obtain the absolute abundance (number per gram) of planktonic foraminifera in the core samples processed by the two methods.

[0068] Observation under a stereomicroscope revealed a significant difference in the quality of the foraminiferal fossil shells obtained by methods A and B. Foraminiferal individuals obtained by method A often had a large amount of rock fragments and other particles adhering to the shell surface, and the shell surface features were not prominent. In contrast, foraminiferal individuals obtained by method B typically had a smoother shell, fewer adhering particles on the shell surface, more distinct sutures, and clearly visible shell surface ornamentation such as edging.

[0069] The results of foraminifera count showed that Method A yielded 1058 planktonic foraminifera per gram of core sample, while Method B yielded 2134 planktonic foraminifera per gram of core sample. This indicates that the extraction efficiency of the extraction method of the present invention is nearly doubled (102%).

[0070] Furthermore, typical genera and species of planktonic and benthic foraminifera were selected from the particulate samples, and benthic foraminifera were selected ( Heterolepa dutemplei ) and planktonic foraminifera ( Paragloborotalia nana One species of each. The foraminifera were observed under an electron microscope. The results are as follows: Figures 2-5 (The scale bar in the figure is 100 μm); and further magnified observation of a local area of ​​the foraminifera's shell surface was conducted to obtain the microstructural features of the shell. The observation results are as follows. Figures 6-9 (The scale bar in the figure is 10μm).

[0071] Figure 2 This is a whole-body observation image of benthic foraminifera obtained by method A. Figure 4 The image shows an overall observation of planktonic foraminifera obtained by method A. It can be seen that the shell surface of the foraminifera obtained by method A has a lot of rock fragments, calcareous nannofossils and other particles bonded together. Figure 3 This is a whole-body observation image of benthic foraminifera obtained by method B. Figure 5 The image shows an overall observation of planktonic foraminifera obtained by method B. It can be seen that the shell surface of the foraminifera obtained by method B has significantly reduced adhesive particles, is clean, has clear shell pores, less filling material, and the suture lines and rims of the shell surface are clear. The oral pores and umbilicus features are easy to observe.

[0072] Upon further magnification, electron microscopy revealed a similar effect in the fine structure of the shell walls of foraminifera. Figure 6 This is a partial observation of the shell surface of benthic foraminifera obtained by method A. Figure 8 The image shows a partial view of the shell surface of planktonic foraminifera obtained by method A. As can be seen from the image, the shell surface of the foraminifera obtained by method A is rough, with a large number of attached mineral crystals and the shell pores are filled. Figure 7 This is a partial observation of the shell surface of benthic foraminifera obtained by method B. Figure 9 The image shows a partial observation of the shell surface of planktonic foraminifera obtained by method B. As can be seen from the image, the foraminifera individuals obtained by method B have fewer attached mineral crystals on the shell surface, less shell pore filling material, and clearer shell pore and shell wall microstructures. In particular, the mesh-like shell wall structure of the shell pores on the shell surface of planktonic foraminifera is the clearest and most obvious.

[0073] Furthermore, when using foraminifera individuals treated with method B for elemental and isotopic pretreatment of foraminifera fossil shells, the fossil crushing operation is easier, and the pretreatment efficiency is at least twice that of foraminifera obtained using method A.

[0074] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0075] It is understood that the above embodiments only illustrate preferred embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can freely combine the above technical features without departing from the concept of the present invention, and can also make several modifications and improvements, all of which fall within the protection scope of the present invention. Therefore, all equivalent transformations and modifications made with respect to the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. A method for extracting calcareous microfossils from consolidated sediments, characterized in that, Includes the following steps: S1. Take core samples or rock fragment samples of consolidated sediments, clean the surface and crush them to obtain fragment samples; S2. Weigh the debris sample, soak it in water and heat it, then freeze it to obtain a frozen sample; S3. Add hydrogen peroxide to the frozen sample and mix, then sieve and wash to obtain the first particulate matter; add a weak alkaline reagent and heat to obtain the first mixture; S4. Add an anti-flocculation agent to the first mixture and mix, then perform ultrasonic treatment to obtain a second mixture; then sieve, wash, dry, and collect particulate samples.

2. The method for extracting calcareous microfossils from consolidated sediments according to claim 1, characterized in that, In step S1, the particle size of the debris sample is less than 3 mm.

3. The method for extracting calcareous microfossils from consolidated sediments according to claim 1, characterized in that, In step S2, the detrital sample is weighed according to the abundance of calcareous microfossils, and the content of the detrital sample in water is 0.05~0.2g / mL.

4. The method for extracting calcareous microfossils from consolidated sediments according to claim 1, characterized in that, In step S2, the debris sample is soaked in water and heated to boiling for 1.5 to 2.5 hours. During the boiling process, water is added to keep the liquid level constant, and then the sample is frozen at -25°C to -15°C until it freezes.

5. The method for extracting calcareous microfossils from consolidated sediments according to claim 1, characterized in that, In step S3, 1-5% hydrogen peroxide is added to the frozen sample, mixed, and allowed to stand for 20-28 hours. Then, the sample is passed through a 45-90μm sieve and washed with water. The volume ratio of the frozen sample to hydrogen peroxide is 1:(1-2).

6. The method for extracting calcareous microfossils from consolidated sediments according to claim 1, characterized in that, In step S3, the weak alkaline reagent is added to the first particulate matter and heated to boiling for 1.5 to 2.5 hours. Water is added during the boiling process to keep the liquid level constant. After cooling, the mixture is allowed to stand for 20 to 28 hours.

7. The method for extracting calcareous microfossils from consolidated sediments according to claim 1, characterized in that, In step S3, the weakly alkaline reagent is a sodium bicarbonate solution with a concentration of 0.05~0.2 g / mL, and the content of the first particulate matter in the weakly alkaline reagent is 0.05~0.15 g / mL.

8. The method for extracting calcareous microfossils from consolidated sediments according to claim 1, characterized in that, In step S4, the antiflocculation agent is added to the first mixture, and after mixing, it is allowed to stand for 0.5 to 1.5 hours, and then ultrasonically treated at a frequency of 30 to 50 kHz for 0.5 to 1.5 minutes.

9. The method for extracting calcareous microfossils from consolidated sediments according to claim 1, characterized in that, In step S4, the anti-flocculation agent is a 0.3-0.7% sodium hexametaphosphate solution, and the volume ratio of the anti-flocculation agent to the first mixture is (0.5-2):

100.

10. The method for extracting calcareous microfossils from consolidated sediments according to claim 1, characterized in that, In step S4, the second mixture is passed through a 45-90 μm sieve and washed with water, and the resulting second particles are dried at 50-70°C.

Images