Quantitative identification method and system suitable for source of ancient dolomite hydrothermal fluid

Abstract

The invention discloses a quantitative identification method and system suitable for an ancient dolomite hydrothermal fluid source, and relates to the technical field of geological exploration, the method comprises the following steps: S1, multi-scale petrology determination of a hydrothermal fluid; s2, performing micro-area-element quantitative determination on the fluid components of the hydrothermal solution; s3, performing micro-zone-isotope quantitative determination on the fluid property of the hydrothermal solution; s4, quantitatively determining the temperature of the hydrothermal fluid; and S5, performing hydrothermal fluid event reduction based on absolute time limitation. Experiments are performed in combination with multiple scales and multiple methods, and the disadvantage that it is difficult to determine data anomalies is solved; the micro-area micro technology is emphasized, and errors caused by the fact that hydrothermal minerals in small adjacent periods are difficult to distinguish during conventional total rock quantitative analysis sampling are avoided; a dating technology is applied to obtain an accurate hydrothermal age, the accurate hydrothermal age is used as a limit, a regional geological background is traced back, a corresponding basin thermal event is reversely deduced through fluid activity time, and determination of hydrothermal fluid activity events and sources in the ancient dolomite is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of geological exploration, and particularly relates to a quantitative identification method and system suitable for the source of hydrothermal fluid of old dolomite. BACKGROUND

[0002] Carbonate reservoir is one of the most important oil and gas reservoirs at present, and its conventional oil and gas reserves account for about 60% of the world, and its production accounts for about 50%. Dolomite reservoir is one of the main exploration targets in carbonate areas, and many large oil and gas reservoirs in the world are produced in dolomite reservoirs. With the increasing exploration degree of shallow oil and gas, the current oil and gas exploration is developing to deep and ultra-deep layers. Therefore, the research on deep old dolomite is very important for deep oil and gas exploration.

[0003] Fluid activity in carbonate sedimentary basin is relatively frequent, and hydrothermal fluid is relatively common in the basin, which has an important influence on the properties of oil and gas reservoirs. The influence of hydrothermal activity on carbonate reservoir is complex, which can increase the porosity of the reservoir and improve the reservoir performance through dolomitization, dissolution and other ways, and can also fill the pores through cementation and reduce the reservoir performance.

[0004] Hydrothermal fluid activity is an important research content of carbonate basin. The past research mainly focuses on rock microanalysis and fluid products, carbon, oxygen and strontium isotope analysis, and the main goal is to identify the fluid period, nature and activity range. There is a lack of quantitative research on the absolute time of hydrothermal fluid, and there is no systematic research method combining various experimental comprehensive analysis to accurately track the source of hydrothermal fluid. SUMMARY

[0005] The present application aims to provide a quantitative identification method and system suitable for the source of hydrothermal fluid of old dolomite, and to propose a systematic research method combining various experimental comprehensive analysis to quantitatively obtain the absolute time of hydrothermal fluid, accurately track the source of hydrothermal fluid, and determine the genesis of dolomite, thereby guiding efficient exploration and development in the field of carbonate rocks. In order to achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0006] The present application provides a quantitative identification method suitable for the source of hydrothermal fluid of old dolomite, which comprises the following steps:

[0007] Step S1, multi-scale petrology determination of hydrothermal fluid;

[0008] Step S2, on the basis of multi-scale petrology determination of hydrothermal fluid, micro-area-element quantitative determination of the composition of hydrothermal fluid is carried out;

[0009] Step S3, on the basis of multi-scale petrology determination of hydrothermal fluid, micro-area-isotope quantitative determination of the properties of hydrothermal fluid is carried out;

[0010] Step S4, on the basis of the multi-scale petrology of the hydrothermal fluid, the temperature of the hydrothermal fluid is quantitatively determined;

[0011] Step S5, according to the micro-area-element quantitative determination result of the hydrothermal fluid composition, the micro-area-isotope quantitative determination result of the hydrothermal fluid property and the quantitative determination result of the hydrothermal fluid temperature, the hydrothermal fluid event restoration based on absolute time limit is carried out.

[0012] Further, the step S1 specifically comprises:

[0013] Step S1.1, the basic data of the study area is analyzed to understand the regional overview, regional burial history, thermal evolution history and tectonic evolution history;

[0014] Step S1.2, through the outcrop, drilling data, seismic data and regional overview, the typical field section or typical drilling core of the hydrothermal development is selected;

[0015] Step S1.3, by observing the hydrothermal cutting relationship and hydrothermal characteristic structure, the main period and cross relationship of the millimeter-hydrothermal are preliminarily clarified;

[0016] Step S1.4, the rock sample of the hydrothermal development is collected, and the sample sampling position is accurately recorded by sketching and photographing;

[0017] Step S1.5, the rock sample of the hydrothermal development is selected, and the cast thin section, fluid inclusion sheet and probe sheet are prepared;

[0018] Step S1.6, the millimeter-micrometer micro-vein body penetration relationship and hydrothermal mineral composition analysis of the cast thin section and fluid inclusion sheet are carried out by polarizing microscope;

[0019] Step S1.7, on the basis of step S1.6, the millimeter-micrometer micro-cementation period and mineral composition analysis of the cast thin section and fluid inclusion sheet are carried out by cathodoluminescence microscope.

[0020] Further, the step S2 specifically comprises:

[0021] Step S2.1, on the basis of the multi-scale petrology of the hydrothermal fluid in step S1, the electron probe is used to carry out the fixed-point quantitative analysis of the major elements of the hydrothermal mineral on the probe sheet;

[0022] Step S2.2, on the basis of step S2.1, the electron probe is used to carry out the micron-nanometer level major element surface scanning on the probe sheet to determine the plane distribution and combination characteristics of the hydrothermal characteristic elements;

[0023] Step S2.3: Use laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to perform point-to-point quantitative analysis of trace elements in the fluid at different stages of the probe sheet;

[0024] In step S2.4, based on step S2.3, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is used to perform trace element surface scanning analysis on the probe slide at different stages to clarify the trace element distribution characteristics of minerals at different stages.

[0025] Furthermore, step S3 specifically includes:

[0026] Step S3.1: Use a handheld dental drill to perform centimeter- to millimeter-level hydrothermal fluid physical sampling on the core sample;

[0027] Step S3.2: Use the MicroMill micro-area sampler to perform millimeter- to micrometer-level hydrothermal fluid physical sampling on the thin-film sample;

[0028] Step S3.3: Samples from different micro-regions are taken and analyzed using an isotope mass spectrometer for δ¹⁸O₅ analysis. 18 O% δ 13 C% isotope testing was used to determine the properties of diagenetic fluids based on the fractionation differences of C and O isotopes from different sources.

[0029] Step S3.4: Samples from different micro-regions are taken and Sr isotope analysis is performed using thermal ionization mass spectrometry. The properties of the diagenetic fluid are determined based on the fractionation differences of Sr isotopes from different sources.

[0030] Further, step S4 specifically includes:

[0031] Step S4.1: Select typical fluid inclusion fragments to conduct fluid inclusion temperature measurement to determine the homogenization temperature of fluid inclusions in different phases;

[0032] Step S4.2: For fluid inclusions that could not be identified in step S4.1, use the MicroMill micro-area sampler to perform millimeter- to micrometer-level hydrothermal fluid physical sampling.

[0033] Step S4.3: The micro-area sample taken in step S4.2 is purified by gas purification based on the cluster isotope (Δ47) pretreatment peripheral device, and then the sample is analyzed by Δ47 isotope testing in the MAT253plus isotope ratio mass spectrometer online.

[0034] Step S4.4: By analyzing the evolutionary background of burial history and thermal evolution history, and combining the test results of steps S4.1 and S4.3, determine the temperature characteristics of hydrothermal fluids in different periods.

[0035] Furthermore, step S5 specifically includes:

[0036] Step S5.1: Based on the homogenization temperature and salinity of brine inclusions in different diagenetic formations, combined with the regional burial history, geothermal history and tectonic evolution history, infer the activity time of different fluids.

[0037] Step S5.2: Select carbonate minerals in the probe sample that can represent hydrothermal fluid activity and perform U and Pb elemental scanning analysis using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS).

[0038] Step S5.3: Subtract the high-value areas of ordinary Pb in the element scan of step S5.2, and select the optimal target area by combining ordinary Pb correction analysis;

[0039] Step S5.4: Perform laser micro-area U-Pb dating analysis on the optimal target area of ​​carbonate minerals using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS).

[0040] Step S5.5: Perform high-precision dating analysis on associated high-U minerals using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS);

[0041] Step S5.6: By comprehensively comparing the ages of carbonate minerals and associated high-U minerals, the regional geological background is traced back, and the corresponding basin thermal events are deduced by the time of fluid activity, thereby determining the hydrothermal fluid activity events and their sources in ancient dolomite.

[0042] This invention also provides a quantitative identification system for the source of hydrothermal fluids in ancient dolomite, the system comprising:

[0043] Multi-scale petrological determination module for multi-scale petrological determination of hydrothermal fluids;

[0044] The micro-area-element quantitative determination module is used to perform micro-area-element quantitative determination of hydrothermal fluid composition based on multi-scale petrological determination of hydrothermal fluids;

[0045] The micro-area-isotope quantitative determination module is used to perform micro-area-isotope quantitative determination of hydrothermal fluid properties based on multi-scale petrological determination of hydrothermal fluids.

[0046] The temperature quantitative determination module is used to quantitatively determine the temperature of hydrothermal fluids based on multi-scale petrological determinations.

[0047] The hydrothermal fluid event reconstruction module is used to reconstruct hydrothermal fluid events based on the micro-area elemental quantitative determination results of hydrothermal fluid composition, the micro-area isotopic quantitative determination results of hydrothermal fluid properties, and the quantitative determination results of hydrothermal fluid temperature, based on absolute time constraints.

[0048] The present invention also provides an electronic device, comprising:

[0049] One or more processors;

[0050] Storage device for storing one or more programs;

[0051] When the one or more programs are executed by the one or more processors, the one or more processors implement the quantitative identification method for the source of hydrothermal fluids in ancient dolomite as described above.

[0052] The present invention also provides a storage medium containing computer-executable instructions, which, when executed by a computer processor, are used to perform the quantitative identification method for hydrothermal fluid sources of ancient dolomite as described above.

[0053] The technical effects and advantages of this invention are as follows:

[0054] 1. This invention combines multi-scale and multi-method experiments, and conducts research in a clear and progressive manner from shallow to deep. The experimental data are cross-referenced, which can promptly detect abnormal data. This avoids the disadvantage of conventional methods being limited in scope and makes it difficult to identify data anomalies.

[0055] 2. This invention focuses on micro-area micro-quantity technology, especially in-situ micro-area technology, which can detect hydrothermal minerals of a single phase on thin sections with extremely high precision, avoiding the errors caused by the difficulty in distinguishing small adjacent hydrothermal minerals when sampling for conventional whole-rock quantitative analysis.

[0056] 3. Since conventional methods lack quantitative research on the absolute time of hydrothermal fluids, this invention applies dating techniques, such as fluid inclusions and U-Pb dating, to obtain accurate hydrothermal ages. Based on these ages, the regional geological background can be traced back, and the corresponding basin thermal events can be easily deduced from the fluid activity time, thus determining the hydrothermal fluid activity events and their origins in ancient dolomite.

[0057] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0058] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0059] Figure 1 A flowchart of a quantitative identification method for the source of hydrothermal fluids in ancient dolomite, provided by the present invention;

[0060] Figure 2 The sample hand specimen image provided for this invention;

[0061] Figure 3 The diagram shows the point-to-point quantitative analysis of major elements in hydrothermal minerals provided by this invention; where A represents pyrite; B represents molybdenite-bearing pyrite; and C represents sphalerite.

[0062] Figure 4 The pyrite image obtained by electron probe microanalysis is provided by this invention.

[0063] Figure 5 Image of molybdenite-bearing pyrite obtained by electron probe microanalysis for the present invention;

[0064] Figure 6 The zinc sphalerite image obtained by electron probe microanalysis is provided by this invention.

[0065] Figure 7 This invention provides an electron probe microanalysis image of barite obtained from an elemental surface scan.

[0066] Figure 8 The molybdenite image obtained by electron probe microanalysis is provided by this invention.

[0067] Figure 9 The apatite image obtained by electron probe elemental surface scanning provided by this invention;

[0068] Figure 10 The δ provided by the present invention 18 O% and δ 13 Scatter plot of C%;

[0069] Figure 11 A schematic diagram of a quantitative identification system for the source of hydrothermal fluids in ancient dolomite, provided by the present invention;

[0070] Figure 12 This is a schematic diagram of an electronic device provided by the present invention. Detailed Implementation

[0071] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0072] The flowchart shown in the attached diagram is merely an illustrative example and does not necessarily include all steps. For example, some steps may be broken down, while others may be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0073] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0074] Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion, such that a process, method, system, product, or device that includes a series of steps or sub-modules is not necessarily limited to those steps or sub-modules that are explicitly listed, but may include other steps or sub-modules that are not explicitly listed or that are inherent to such process, method, product, or device.

[0075] The design concept of this invention includes: performing basic petrological identification on several collected rock samples, and preferably performing isotopic analysis to determine the hydrothermal phases, temperatures, and sources; performing major and trace element analysis on the preliminarily identified samples to identify the compositional characteristics of fluids in each phase; performing dating analysis on the minerals formed by representative fluids in each phase to clarify the activity time of each fluid phase; and linking fluids with identified phases, temperatures, sources, compositions, and activity times with corresponding thermal events for comprehensive analysis. This invention combines multi-scale qualitative observation technology and quantitative testing technology, focusing on micro-area trace technology, to accurately identify the source of hydrothermal fluids in deep ancient dolomite, and has strong feasibility and applicability.

[0076] Therefore, this invention discloses a quantitative identification method applicable to the source of hydrothermal fluids in ancient dolomite. Figure 1 A flowchart illustrating a quantitative identification method for the source of hydrothermal fluids in ancient dolomite, provided by this invention, is shown below. Figure 1 As shown, the method includes the following steps:

[0077] Step S1, Multi-scale petrological determination of hydrothermal fluids:

[0078] Step S1.1: Summarize and analyze the basic data of the study area to understand the regional overview, regional burial history, thermal evolution history and tectonic evolution history;

[0079] Step S1.2: Based on field outcrops, drilling data, seismic data, and regional overview, select typical field profiles or typical drilling cores with hydrothermal development;

[0080] Step S1.3: By observing the hydrothermal cutting relationship and hydrothermal characteristic structures (such as zebra-like structures, expanded breccia, etc.), the main phases and intersections of meter- to centimeter-scale hydrothermal fluids are preliminarily clarified.

[0081] Step S1.4: Collect rock samples from hydrothermal vents and accurately record the sampling locations using sketching and photography.

[0082] Step S1.5: Select rock samples with hydrothermal development and prepare cast thin sections, fluid inclusion sections and probe sections;

[0083] Step S1.6: Perform centimeter- to millimeter-level microscopic vein penetration relationships and hydrothermal mineral composition analysis on cast thin sections and fluid inclusion sections using a polarizing microscope;

[0084] Based on steps S1.7 and S1.6, the casting thin sections and fluid inclusion sections are analyzed by centimeter- to millimeter-level microscopic cementation stages and mineral composition using a cathodoluminescence microscope.

[0085] Step S2: Micro-area elemental quantitative determination of hydrothermal fluid composition:

[0086] Step S2.1: Based on the multi-scale petrological determination of hydrothermal fluids in Step S1, use an electron probe to perform fixed-point quantitative analysis of major elements in hydrothermal minerals (such as saddle dolomite, sphalerite, galena, barite, fluorite, pyrite, and siliceous minerals) on the probe slide.

[0087] Step S2.2: Based on step S2.1, use an electron probe to perform micron-nano-scale major element surface scanning on the probe sheet to determine the planar distribution and combination characteristics of hydrothermal characteristic elements (such as Mg, Ca, Si, Fe, Mn, Sr, Zn).

[0088] Step S2.3: Use laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to perform point-to-point quantitative analysis of trace elements in the fluid at different stages of the probe sheet;

[0089] Step S2.4: Based on step S2.3, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is used to perform trace element surface scanning analysis on the probe slide for different phases of fluids to clarify the distribution characteristics of trace elements (such as Eu, Ce, Y, Cd, Ge, etc.) of minerals in different phases.

[0090] Step S3: Micro-area-isotopic quantitative determination of hydrothermal fluid properties:

[0091] Step S3.1: Use a handheld dental drill to perform centimeter- to millimeter-level hydrothermal fluid physical sampling on the core sample;

[0092] Step S3.2: Use the MicroMill micro-area sampler to perform millimeter- to micrometer-level hydrothermal fluid physical sampling on the thin-film sample;

[0093] Step S3.3: Samples from different micro-regions are taken and analyzed using an isotope mass spectrometer for δ¹⁸O₅ analysis. 18 O% δ 13 C% isotope testing was used to determine the properties of diagenetic fluids based on the fractionation differences of C and O isotopes from different sources.

[0094] Step S3.4: Samples from different micro-regions are taken and Sr isotope analysis is performed using thermal ionization mass spectrometry. The properties of the diagenetic fluid are determined based on the fractionation differences of Sr isotopes from different sources.

[0095] Step S4: Quantitative determination of hydrothermal fluid temperature:

[0096] Step S4.1: Select typical fluid inclusion fragments to conduct fluid inclusion temperature measurement to determine the homogenization temperature of fluid inclusions in different phases;

[0097] Step S4.2: For fluid inclusions that could not be identified in step S4.1, use the MicroMill micro-area sampler to perform millimeter- to micrometer-level hydrothermal fluid physical sampling.

[0098] Step S4.3: The micro-area sample taken in step S4.2 is purified by gas purification based on the cluster isotope (Δ47) pretreatment peripheral device, and then the sample is analyzed by Δ47 isotope testing in the MAT253plus isotope ratio mass spectrometer online.

[0099] Step S4.4: By analyzing the evolutionary background of burial history and thermal evolution history, and combining the test results of steps S4.1 and S4.3, determine the temperature characteristics of hydrothermal fluids in different periods.

[0100] Step S5: Reconstruction of hydrothermal fluid events based on absolute time constraints:

[0101] Step S5.1: Based on the homogenization temperature and salinity of brine inclusions in different diagenetic formations, combined with the regional burial history, geothermal history and tectonic evolution history, infer the activity time of different fluids.

[0102] Step S5.2: Select carbonate minerals in the probe sample that can represent hydrothermal fluid activity and perform U and Pb elemental scanning analysis using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS).

[0103] Step S5.3: Subtract the high-value areas of ordinary Pb in the element scan of step S5.2, and select the optimal target area by combining ordinary Pb correction analysis;

[0104] Step S5.4: Perform laser micro-area U-Pb dating analysis on the optimal target area of ​​carbonate minerals using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS).

[0105] Step S5.5: Perform high-precision dating analysis on associated high-U minerals, such as zircon, monazite, xenotime, sphene, rutile, apatite, and garnet, using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS).

[0106] Step S5.6: By comprehensively comparing the ages of carbonate minerals and associated high-U minerals, the regional geological background is traced back, and the corresponding basin thermal events are deduced by the time of fluid activity, thereby determining the hydrothermal fluid activity events and their sources in ancient dolomite.

[0107] Example:

[0108] Taking the dolomite from the Oyipikexi Gully in the Tarim Basin and some hydrothermal mineral samples from the Qitan-1 well as examples, this invention provides a quantitative identification method for the source of hydrothermal fluids in ancient dolomite, comprising the following steps:

[0109] Step S1: Multi-scale petrological determination of hydrothermal fluids:

[0110] By reviewing past research literature on the Tarim Basin, we summarized and analyzed basic data such as the region's overview, burial history, thermal evolution history, and tectonic evolution history. Based on the survey data, we selected the Oypiksi Valley section, which has significant hydrothermal activity. Figure 2The images provided for this invention are hand specimen images, where a is a photograph of sample P1-209, a section of the Aoyipikexi Gully, showing karst caves filled with saddle-shaped dolomite (MS); b is a single-polarized thin section scan of sample P1-209, a section of the Aoyipikexi Gully, showing karst caves filled with saddle-shaped dolomite (MS), where hydrothermal fluids dissolved the matrix dolomite (MD) to form solution pores, and saddle-shaped dolomite (SD) directly precipitated from the hydrothermal fluids to fill the solution pores; c is a photograph of sample P1-212, showing coarse-grained saddle-shaped dolomite (SD) not completely filling the karst caves, with calcite cement (Cal) visible later; d is a photograph of sample P4-150, showing coarse-grained saddle-shaped dolomite (SD) not completely filling the caves. Karst caves, retaining residual dissolution pores; e is a single-polarized thin section scan image of P4-147, retaining residual intercrystalline pores between saddle-shaped dolomite (SD); f is a single-polarized thin section scan image of P1-211, hydrothermal fluid-modified matrix dolomite (MD), with matrix dolomite cement (SD) deposited in the cave; g is a hand specimen image of P1-210, showing surrounding rock breccia distributed in a "floating" manner between the saddle-shaped dolomite; h is a single-polarized thin section scan image of 6001.4m from Qitan 1 well, showing saddle-shaped dolomite (SD) filling the fractures; i is in the same field of view as h, a cathodoluminescence image of 6001.4m thin section from Qitan 1 well, showing saddle-shaped dolomite (SD) filling the fractures. During the observation of rock samples from the Oypiksi Valley, multiple phases of hydrothermal activity were identified. Due to differences in mineral composition between different phases, saddle-shaped dolomite and calcite of varying coarse and fine crystal types were identified in the hydrothermal veins of the samples. Based on different lithologies, six phases of hydrothermal activity can be divided. Figure 2 a, 2c); hydrothermal characteristic structures such as expanded breccia were identified ( Figure 2 d, 2g), to preliminarily clarify the main phases and overlapping relationships of meter- to centimeter-scale hydrothermal fluids.

[0111] Thin sections were prepared, and centimeter- to millimeter-level microscopic vein-cutting relationships and hydrothermal mineral composition analyses were performed on cast thin sections and fluid inclusion sections using a polarizing microscope. In the observation of ordinary thin sections of the Oypiksi Gorge samples, hydrothermal erosion-induced pores in the matrix dolomite were identified, filled with multiple phases of hydrothermal minerals. The earliest phases of minerals formed at the pore edges; due to sufficient pore space, their growth was relatively euhedral. Later phases of hydrothermal minerals, constrained by pore space, exhibited poor euhedral growth. Based on this, two phases of hydrothermal activity could be distinguished at the microscopic scale. Figure 2 b, 2e, 2f); When using cathodoluminescence microscopy to analyze the centimeter-to-millimeter microstructure of cementation stages and mineral composition of the probe section of Qitan 1 well, saddle-shaped dolomite filling the fractures can be identified. Different stages of hydrothermal fluids will show different shades of color under cathodoluminescence, based on which approximately nine stages of hydrothermal activity can be identified. Figure 2 h、2i).

[0112] Step S2: Quantitative determination of the micro-area elemental composition of the hydrothermal fluid:

[0113] When performing major element analysis on samples from the Oypicsy Valley using electron probe microanalysis, hydrothermal minerals such as pyrite, sphalerite, and molybdenite-bearing pyrite were identified through point-to-point quantitative analysis and by calculating the proportions of each element in the data table. Figure 3 (Table 1). Further electron probe microanalysis of the probe sheet at the micrometer-nanometer scale allows for direct identification of the distribution of different elements, including hydrothermal minerals such as barite, pyrite, apatite, sphalerite, and molybdenite. Figure 4 , Figure 5 , Figure 6 , Figure 7 , Figure 8 , Figure 9 ).

[0114] Table 1. Quantitative and location-specific analysis of major elements in hydrothermal minerals.

[0115]

[0116]

[0117] Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was used to perform point-to-point quantitative analysis of trace elements in fluids at different stages of a probe slide. LA-ICP-MS can achieve quantitative determination of trace element composition at a specific point in a sample to determine the properties of hydrothermal fluids.

[0118] Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was used to perform trace element surface scanning analysis on the probe slides of fluids from different phases. It can perform elemental surface scanning on samples in a certain field of view, and show the distribution of each trace element in the field of view by using different colors to represent different elements, thus clarifying the distribution characteristics of trace elements (such as Eu, Ce, Y, Cd, Ge, etc.) in minerals from different phases.

[0119] Step S3: Micro-area-isotopic quantitative determination of hydrothermal fluid properties:

[0120] Centimeter- to millimeter-level hydrothermal fluid physical sampling was performed on core samples using a handheld dental drill. During sampling, both the sample and the drill bit were cleaned once with pure water and once with alcohol to ensure no impurities were contaminated. Millimeter- to micrometer-level hydrothermal fluid physical sampling was performed on thin section samples using a Micrometer- to micrometer-level micro-area sampler.

[0121] When sampling micro-areas of hydrothermal dolomite and surrounding rocks in the Oypiksi Valley and performing CO isotope analysis using isotope mass spectrometry, δ¹⁸O⁻ from different sources was observed. 18 O% δ 13C% isotopes exhibit fractionation differences, which can be observed by plotting δ¹⁸. 18 O% and δ 13 The scatter plot of C% provides a clear view of the saddle-shaped dolomite δ0. 18 O% and δ 13 The C% value is the most negative, indicating significant hydrothermal activity, while micritic microbial rocks are unaffected by hydrothermal activity. 18 O% δ 13 The C% isotope is relatively positive, while the microbial dolomite, with its residual structure in the surrounding rock, is partially influenced by hydrothermal activity and falls somewhere in between; different rock types can be clearly distinguished. Figure 10 ).

[0122] Sr isotope analysis was performed on micro-region samples from different periods using thermal ionization mass spectrometry, and the properties of diagenetic fluids were determined based on the fractionation differences of Sr isotopes from different sources.

[0123] Step S4: Quantitative determination of hydrothermal fluid temperature:

[0124] Fluid inclusion thermometry was performed on typical fluid inclusion fragments to determine the homogenization temperature of fluid inclusions in different stages. It was assumed that fluid inclusions formed in a homogeneous state. Over time, temperature and pressure changes caused dissolved gases in the initially homogeneous fluid to fractionate and form bubbles within the inclusions. Therefore, by gradually heating the inclusions until they became homogeneous again, the temperature at which they formed can be considered their initial temperature. For stages without inclusions, millimeter- to micrometer-level hydrothermal fluid physical sampling was performed using a MicroMill micro-area sampler. Gas purification was performed using a cluster isotope (Δ47) pretreatment peripheral device, and online Δ47 isotope analysis was conducted using a MAT253plus isotope ratio mass spectrometer to determine the temperature of the corresponding fluid. Δ47 isotope thermography analysis of foamy dolomite, residual structure tuffaceous dolomite, fine-grained dolomite, and fractured saddle-shaped dolomite revealed the specific hydrothermal fluid temperatures as follows: foamy dolomite Δ47 temperature 56.575℃, residual structure tuffaceous dolomite Δ47 temperature 81.473℃, fine-grained dolomite Δ47 temperature 113.976℃, and fractured saddle-shaped dolomite Δ47 temperature 134.554℃. These temperatures were correlated with their δ¹⁸O values. 18 O% δ 13 The C% isotope data are consistent; the higher the temperature, the higher the δ... 18 O% δ 13 The more negative the C% value, the more pronounced the hydrothermal characteristics (Table 2). Combining the above two methods, it is possible to construct a systematic temperature characteristic profile of hydrothermal fluids in different phases.

[0125] Table 2. Δ47 isotope analysis and U-Pb dating analysis of different rock types.

[0126]

[0127] Step S5: Reconstruction of hydrothermal fluid events based on absolute time constraints:

[0128] Based on the temperature determined in step S4, and combined with the regional burial history, geothermal history, and tectonic evolution history, the activity time of different fluid phases is inferred. Carbonate minerals representative of hydrothermal fluid activity are selected from the probe sample and subjected to U and Pb elemental scanning analysis using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). High-value areas of ordinary Pb in the elemental scan are subtracted, and combined with ordinary Pb correction analysis, the optimal target area is selected for U-Pb dating analysis.

[0129] Laser micro-area U-Pb dating analysis was performed on the optimal target area of ​​carbonate minerals using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). High-precision dating analysis was also performed on associated high-U minerals such as zircon, monazite, xenotime, sphene, rutile, apatite, and garnet to determine the specific absolute age of formation of the minerals and associated high-U minerals in this period (Table 2). U-Pb dating analysis of foamy dolomite, residual structured clotted dolomite, fine-grained dolomite, and fractured saddle-shaped dolomite yielded the following precise ages: foamy dolomite (560±26 Ma) and residual structured clotted dolomite (576±16 Ma) correspond to the Late Sinian tectonic-thermal event in the Tarim Uplift; fine-grained dolomite (483±6.8 Ma) corresponds to a thermal event in the central and western Tarim Basin from 460.2 to 484.5 Ma; and fractured saddle-shaped dolomite (215±30 Ma) corresponds to an Early Permian volcanic thermal event in the Tarim Basin. Simultaneously, the ages were correlated with Δ47 isotope thermography and δ¹⁴ Pb dating. 18 O% δ 13 The C% isotope analysis was consistent, reconstructing the thermal events corresponding to the formation of the sample (Table 2).

[0130] By comprehensively comparing the ages of carbonate minerals and associated high-U minerals, tracing back the regional geological background, and inferring the corresponding basin thermal events through the timing of fluid activity, the hydrothermal fluid activity events and their origins in ancient dolomite can be determined.

[0131] Based on the above method, the present invention also discloses a quantitative identification system applicable to the source of hydrothermal fluids in ancient dolomite. Figure 11 A schematic diagram of a quantitative identification system for the source of hydrothermal fluids in ancient dolomite, provided by this invention, is shown below. Figure 11As shown, the system includes: a multi-scale petrological determination module 201 for multi-scale petrological determination of hydrothermal fluids; a micro-area-element quantitative determination module 202 for performing micro-area-element quantitative determination of hydrothermal fluid composition based on the multi-scale petrological determination of hydrothermal fluids; a micro-area-isotope quantitative determination module 203 for performing micro-area-isotope quantitative determination of hydrothermal fluid properties based on the multi-scale petrological determination of hydrothermal fluids; a temperature quantitative determination module 204 for performing quantitative determination of hydrothermal fluid temperature based on the multi-scale petrological determination of hydrothermal fluids; and a hydrothermal fluid event reconstruction module 205 for reconstructing hydrothermal fluid events based on absolute time constraints, according to the results of the micro-area-element quantitative determination of hydrothermal fluid composition, the micro-area-isotope quantitative determination of hydrothermal fluid properties, and the quantitative determination of hydrothermal fluid temperature.

[0132] Based on the same inventive concept, the present invention also provides an electronic device. Figure 12 A schematic diagram of an electronic device provided by the present invention, such as... Figure 12 As shown, the electronic device includes at least one processor 301, at least one communication interface 302, at least one memory 303, and at least one communication bus 304; wherein the processor 301, communication interface 302, and memory 303 communicate with each other through the communication bus 304.

[0133] Memory 303 stores computer programs;

[0134] The processor 301, when executing the program stored in the memory 303, implements the quantitative identification method applicable to the source of hydrothermal fluids in ancient dolomite.

[0135] Optionally, the communication interface can be an interface of a communication module, such as the interface of a GSM module; the processor may be a CPU, an Application Specific Integrated Circuit (ASIC), or one or more integrated circuits configured to implement embodiments of the present invention. The memory may include high-speed RAM and may also include non-volatile memory, such as at least one disk storage device. The memory stores a program, and the processor calls the program stored in the memory to execute some or all of the above-described method embodiments.

[0136] Based on the same inventive concept, the present invention also provides a computer-readable storage medium storing a computer program, which, when executed, implements some or all of the above-described method embodiments. Optionally, the storage medium may be a non-transitory computer-readable storage medium, such as a ROM, random access memory (RAM), CD-ROM, magnetic tape, floppy disk, and optical data storage device.

[0137] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A quantitative identification method for the source of hydrothermal fluids in ancient dolomite, characterized in that, The method includes the following steps: Step S1: Multi-scale petrological determination of hydrothermal fluids; Step S2: Based on the multi-scale petrological determination of hydrothermal fluids, perform micro-area-element quantitative determination of hydrothermal fluid composition; Step S3: Based on the multi-scale petrological determination of hydrothermal fluids, perform micro-area-isotopic quantitative determination of hydrothermal fluid properties; Step S4: Based on the multi-scale petrological determination of hydrothermal fluids, the temperature of the hydrothermal fluids is quantitatively determined; Step S5: Based on the results of micro-area elemental quantitative determination of hydrothermal fluid composition, micro-area isotopic quantitative determination of hydrothermal fluid properties, and quantitative determination of hydrothermal fluid temperature, perform hydrothermal fluid event reconstruction based on absolute time constraints.

2. The method for quantitative identification of the source of hydrothermal fluids in ancient dolomite as described in claim 1, characterized in that, Step S1 specifically includes: Step S1.1: Summarize and analyze the basic data of the study area to understand the regional overview, regional burial history, thermal evolution history and tectonic evolution history; Step S1.2: Based on field outcrops, drilling data, seismic data, and regional overview, select typical field profiles or typical well cores with hydrothermal development; Step S1.3: By observing the hydrothermal cutting relationship and hydrothermal characteristic structure, the main phases and intersections of meter- to centimeter-scale hydrothermal fluids are preliminarily clarified; Step S1.4: Collect rock samples from hydrothermal vents and accurately record the sampling locations using sketching and photography. Step S1.5: Select rock samples with hydrothermal development and prepare cast thin sections, fluid inclusion sections and probe sections; Step S1.6: Perform centimeter- to millimeter-level microscopic vein penetration relationships and hydrothermal mineral composition analysis on cast thin sections and fluid inclusion sections using a polarizing microscope; Based on steps S1.7 and S1.6, the casting thin sections and fluid inclusion sections are analyzed by centimeter- to millimeter-level microscopic cementation stages and mineral composition using a cathodoluminescence microscope.

3. The method for quantitative identification of the source of hydrothermal fluids in ancient dolomite as described in claim 1, characterized in that, Step S2 specifically includes: Step S2.1: Based on the multi-scale petrological determination of hydrothermal fluids in Step S1, use an electron probe to perform point-to-point quantitative analysis of major elements in hydrothermal minerals on the probe slide; Step S2.2: Based on step S2.1, use an electron probe to perform micron-nano-scale surface scanning of major elements on the probe sheet to determine the planar distribution and combination characteristics of hydrothermal characteristic elements; Step S2.3: Use laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to perform point-to-point quantitative analysis of trace elements in the fluid at different stages of the probe sheet; In step S2.4, based on step S2.3, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is used to perform trace element surface scanning analysis on the probe slide at different stages to clarify the trace element distribution characteristics of minerals at different stages.

4. The method for quantitative identification of the source of hydrothermal fluids in ancient dolomite as described in claim 1, characterized in that, Step S3 specifically includes: Step S3.1: Use a handheld dental drill to perform centimeter- to millimeter-level hydrothermal fluid physical sampling on the core sample; Step S3.2: Use the MicroMill micro-area sampler to perform millimeter- to micrometer-level hydrothermal fluid physical sampling on the thin-film sample; Step S3.3: Samples from different micro-regions are taken and analyzed using an isotope mass spectrometer for δ¹⁸O₅ analysis. 18 O% δ 13 C% isotope testing was used to determine the properties of diagenetic fluids based on the fractionation differences of C and O isotopes from different sources. Step S3.4: Samples from different micro-regions are taken and Sr isotope analysis is performed using thermal ionization mass spectrometry. The properties of the diagenetic fluid are determined based on the fractionation differences of Sr isotopes from different sources.

5. The quantitative identification method for the source of hydrothermal fluids in ancient dolomite as described in claim 1, characterized in that, Step S4 specifically includes: Step S4.1: Select typical fluid inclusion fragments to conduct fluid inclusion temperature measurement to determine the homogenization temperature of fluid inclusions in different phases; Step S4.2: For fluid inclusions that could not be identified in step S4.1, use the MicroMill micro-area sampler to perform millimeter- to micrometer-level hydrothermal fluid physical sampling. Step S4.3: The micro-area sample taken in step S4.2 is purified by gas purification based on the cluster isotope (Δ47) pretreatment peripheral device, and then the sample is analyzed by Δ47 isotope testing in the MAT253plus isotope ratio mass spectrometer online. Step S4.4: By analyzing the evolutionary background of burial history and thermal evolution history, and combining the test results of steps S4.1 and S4.3, determine the temperature characteristics of hydrothermal fluids in different periods.

6. The quantitative identification method for the source of hydrothermal fluids in ancient dolomite as described in claim 1, characterized in that, Step S5 specifically includes: Step S5.1: Based on the homogenization temperature and salinity of brine inclusions in different diagenetic formations, combined with the regional burial history, geothermal history and tectonic evolution history, infer the activity time of different fluids. Step S5.2: Select carbonate minerals in the probe sample that can represent hydrothermal fluid activity and perform U and Pb elemental scanning analysis using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Step S5.3: Subtract the high-value areas of ordinary Pb in the element scan of step S5.2, and select the optimal target area by combining ordinary Pb correction analysis; Step S5.4: Perform laser micro-area U-Pb dating analysis on the optimal target area of ​​carbonate minerals using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Step S5.5: Perform high-precision dating analysis on associated high-U minerals using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS); Step S5.6: By comprehensively comparing the ages of carbonate minerals and associated high-U minerals, the regional geological background is traced back, and the corresponding basin thermal events are deduced by the time of fluid activity, thereby determining the hydrothermal fluid activity events and their sources in ancient dolomite.

7. A quantitative identification system for the source of hydrothermal fluids in ancient dolomite, characterized in that, The system includes: Multi-scale petrological determination module for multi-scale petrological determination of hydrothermal fluids; The micro-area-element quantitative determination module is used to perform micro-area-element quantitative determination of hydrothermal fluid composition based on multi-scale petrological determination of hydrothermal fluids; The micro-area-isotope quantitative determination module is used to perform micro-area-isotope quantitative determination of hydrothermal fluid properties based on multi-scale petrological determination of hydrothermal fluids. The temperature quantitative determination module is used to quantitatively determine the temperature of hydrothermal fluids based on multi-scale petrological determinations. The hydrothermal fluid event reconstruction module is used to reconstruct hydrothermal fluid events based on the micro-area elemental quantitative determination results of hydrothermal fluid composition, the micro-area isotopic quantitative determination results of hydrothermal fluid properties, and the quantitative determination results of hydrothermal fluid temperature, based on absolute time constraints.

8. An electronic device, characterized in that, include: One or more processors; Storage device for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the quantitative identification method for hydrothermal fluid sources of ancient dolomite as described in any one of claims 1-6.

9. A storage medium containing computer-executable instructions, characterized in that, The computer-executable instructions, when executed by a computer processor, are used to perform the quantitative identification method for hydrothermal fluid sources of ancient dolomite as described in any one of claims 1-6.

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