A method for identifying pre-existing structures of a porphyry ore-forming system

Abstract

The application discloses a method for identifying pre-existing structures of porphyry metallogenic system, and belongs to the technical field of magmatic hydrothermal deposit exploration, and comprises the following steps: carrying out structural analysis of a mining area, and preparing a structural outline map of the mining area; dividing structural activity stages, and constructing a structural evolution sequence of the mining area; analyzing and determining diagenetic and metallogenic ages of a metallogenic rock mass and an ore body, determining generation and formation sequences among the structures, the metallogenic rock mass and the ore body, and preliminarily screening out pre-existing structures; analyzing geometry, kinematics, mechanics, material and chronology of the preliminarily screened pre-existing structures, and extracting identification characteristic marks of the pre-existing structures; and identifying the pre-existing structures by comprehensively considering the structural evolution sequence, the generation and formation sequences among the structures, the metallogenic rock mass and the ore body, and the identification characteristic marks of the pre-existing structures. The method solves the problem of rapidly identifying pre-existing structures in the process of analyzing ore-controlling structures in the porphyry metallogenic system, and can provide a basis for spatial positioning and determination of a concealed metallogenic rock mass and an ore body in view of the obvious rock-controlling and ore-controlling effects of the pre-existing structures.

Description

Technical Field

[0001] This invention relates to a method for identifying pre-existing structures in porphyry mineralization systems, belonging to the field of magmatic hydrothermal deposit exploration technology. Background Technology

[0002] Tectonic activity is a crucial factor controlling the formation and distribution of almost all types of mineral deposits. In porphyry metallogenic systems, major sources of metals such as copper, molybdenum, and gold worldwide, tectonic control over rock formations and ore deposits is particularly prominent. The temporal relationship between structures and ore-forming rocks and ore bodies within porphyry metallogenic systems can be categorized into three types: structures predating the diagenetic and metallogenic geological period (pre-existing structures, structures formed and existing before the metallogenic period) or pre-mineralization structures; structures active concurrently during the diagenetic and metallogenic geological period (metallogenic structures); and structures formed after diagenesis and mineralization (post-mineralization structures). Among these, metallogenic structures directly control the formation and distribution of ore-forming rocks and ore bodies. Post-mineralization structures often disrupt and alter the spatial distribution of ore-forming rocks and ore bodies. Because of their clear spatial distribution relationship with ore-forming rocks and deposits (bodies), these two types of structures are relatively easy to identify, and their rock-controlling and ore-controlling effects are relatively well-studied. Pre-existing structures, on the other hand, often indirectly control the formation and distribution of ore-forming rocks and ore bodies, and often constrain the emplacement of ore-forming rocks and the occurrence of mineralization. Therefore, identifying pre-existing structures is also of great significance for determining the spatial location of ore-forming rock bodies and ore deposits (bodies).

[0003] The defining characteristic of pre-existing structures is their formation and existence prior to the mineralization period. During the formation of ore-forming intrusive bodies and ore bodies, pre-existing structures often undergo activation or inherited development, exhibiting more complex geometric morphologies, movement patterns, mechanical property transformation processes, and material composition. Simultaneously, pre-existing structures, acting as boundary conditions, influence the development characteristics of structures during and after mineralization in the mining area. Furthermore, as structures existing before diagenesis and mineralization, magma and ore-forming fluids preferentially utilize these structures for emplacement and migration, becoming sites for shallow positioning of intrusive bodies and ore bodies. Therefore, these characteristics become important indicators for identifying pre-existing structures. Through structural analysis, tectonic activity period classification, and analysis of the generation sequence of structures—ore-forming intrusive bodies—ore bodies, pre-existing structures are initially screened out. Further detailed analysis of the characteristics of pre-existing structures is then conducted to extract identifying features, ultimately identifying the pre-existing structures controlling the porphyry mineralization system. Summary of the Invention

[0004] This invention addresses the technical challenge of identifying pre-existing structures within porphyry mineralization systems. It provides a method for controlling the identification of pre-existing structures in porphyry mineralization systems. Based on the compilation of a structural outline map of the mining area and the construction of a structural evolution sequence, the method combines the chronological order of formation of structures, ore-forming rock bodies, and ore bodies to initially screen pre-existing structures. Then, it conducts detailed analysis of the characteristics of pre-existing structures, extracting their geometric, kinematic, mechanical, material, and geochronological identification features, and finally identifies the pre-existing structures.

[0005] The method for identifying pre-existing structures in porphyry mineralization systems according to the present invention includes the following four steps:

[0006] S1: Within the porphyry metallogenic system mining area, conduct large-scale (1:100-1:1000) detailed structural profile measurements along several parallel and / or perpendicular exploration lines. Analyze, describe, and determine the types of structures developed within the mining area (folds, faults, joints, thrust structures, intrusive contact structures, etc.), structural scale (length, width, etc.), and spatial distribution relationships of structures (interpenetration, restriction, truncation, merging, etc.). Classify the ore-controlling structural levels (orefield structures, deposit structures, orebody structures, etc.). Conduct structural analysis of the mining area, and study and summarize the occurrence characteristics (strike, dip) of different types of structures. Based on the dip angle, geometric morphological characteristics (width, extension, depth, and structural surface morphology—straight, serrated, wavy, gently wavy, gradually wide and steeply narrow, etc.), movement characteristics (leftward or rightward movement on the plane; upward or downward movement on the cross-section, etc.), and mechanical properties and their transformation processes (compressive, tensile, torsional, compressive-torsional, tensile-torsional, etc., and compressive → tensile, compressive → torsional, tensile → torsional, etc.), a structural outline map of the mining area is compiled. Combining the spatial distribution relationship of the structure and the transformation process of the structural mechanical properties, the tectonic activity periods and the transformation process of the tectonic stress field are determined, and the tectonic evolution sequence of the mining area is constructed.

[0007] S2: Conduct research on the temporal distribution patterns of rock masses and ore bodies within the mining area.

[0008] Organize and summarize isotopic age data (U-Pb isotopic age, K-Ar isotopic age, Ar-Ar isotopic age, Re-Os isotopic age, etc.) of different types of rock bodies and ore bodies in the mining area, analyze the evolutionary sequence of different types of rock bodies and the formation age of the ore deposit, or study the sequential intersection relationship between them, and determine the ore-forming rock bodies based on the consistency between the diagenetic age and the metallogenic age; based on the tectonic evolution sequence of the mining area determined in step S1, analyze the temporal and spatial relationship between the formation and distribution of the tectonics and the ore-forming rock bodies and ore bodies, clarify the chronological order of the formation of the tectonics and the ore-forming rock bodies and ore bodies, and then preliminarily screen out the pre-existing structures;

[0009] S3: For the pre-existing structures initially identified in step S2, conduct detailed analysis of their geometry, kinematics, mechanics, material science, geochronology, and rock-controlling and mineral-controlling characteristics. Based on the unique properties of the pre-existing structures, extract characteristic markers for identification. The specific markers and methods are as follows:

[0010] (1) Pre-existing structures have a time limit attribute. This is the most important indicative attribute of pre-existing structures. Their formation and existence must have preceded the period of diagenesis and mineralization in the porphyry mineralization system. Pre-existing structures can be identified based on the time limit reflected by the stratigraphic position (or other marker layers that can reflect geological age) that the structure contains and cuts through, the time limit reflected by the inclusion and cutting relationship between the structure and the rock mass and ore body, the time limit reflected by the composite modification characteristics exhibited by the structure itself and / or the time limit reflected by the cutting, restriction, and merging relationship with other structures.

[0011] (2) Pre-existing structures have reactivation properties. Pre-existing structures are the weakest zones that are most easily released by subsequent stress. In later tectonic activities, their activation and inheritance development are very common and they are more likely to form than newly formed structures.

[0012] (3) Pre-existing structures possess complex geometric properties. Given the reactivation nature of pre-existing structures, they often exhibit complex geometric morphological features, reflecting the comprehensive morphology formed by the influence of multiple tectonic activities, including those during the metallogenic geological period. Therefore, in-depth analysis of the geometric morphology and complexity of structures can serve as one of the indicators for identifying and determining pre-existing structures.

[0013] (4) Pre-existing structures possess complex kinematic properties. Given the reactivation properties of pre-existing structures, they often exhibit complex movement patterns, reflecting the comprehensive results of multiple tectonic activities. Suppose there exists a north-south trending fault F. Analysis shows that this fault simultaneously exhibits three movement patterns: hanging wall uplift, relative horizontal slip between the two walls, and hanging wall subsidence. This indicates that the fault is not the product of a single tectonic activity, but rather a movement pattern formed by three separate tectonic activities. Furthermore, assuming that diagenesis and mineralization occurred during the second phase of tectonic activity, then the hanging wall uplift reflects the movement pattern preserved by the pre-existing tectonic activity.

[0014] (5) Pre-existing structures possess complex mechanical properties. Given the reactivation properties of pre-existing structures, they often exhibit complex transformation processes of mechanical properties, reflecting the different tectonic stress field characteristics of multiple tectonic activities. Similarly, taking the north-south trending fault F assumed in "(4) Pre-existing structures possess complex kinematic properties" as an example, this fault simultaneously exhibits three movement modes: hanging wall uplift, relative horizontal slip between the two walls, and hanging wall subsidence. Generally, the mechanical properties reflected by this fault are compressive, torsional, and tensile, respectively. This also indicates that the fault is not a product of a single tectonic activity, but rather a product of three tectonic activities and the transformation process of these mechanical properties. It also reflects the tectonic stress fields of these three tectonic activities (based on the maximum principal stress σ1 in the horizontal plane) as near-east-west compression, northwest or northeast compression, and near-north-south compression, respectively. Similarly, assuming that diagenesis and mineralization occur during the second tectonic activity, then the compressive properties reflect the mechanical properties retained by the pre-existing tectonic activities.

[0015] (6) Pre-existing structures possess complex material properties. Given their reactivation properties, pre-existing structures often exhibit complex tectonic rock compositions, reflecting the comprehensive results of tectonic rock material composition generated by multiple phases of tectonic activity. Simultaneously, the control of pre-existing structures on diagenesis and mineralization varies; some components of pre-existing structures contribute nothing to diagenesis and mineralization, while others play a certain role. Therefore, the tectonic rock composition of host rocks and mineralization sites does not contain the material components of rock masses and ore bodies, and often shows no traces of hydrothermal alteration or mineralization; while the tectonic rock composition of host rocks and mineralization sites reflects the material components of rock masses and ore bodies, and often exhibits a certain degree of hydrothermal alteration or mineralization.

[0016] (7) Pre-existing structures have boundary effect properties. When pre-existing structures are active, they will develop different structural traces and produce different structural combination patterns due to the influence of different types and directions of pre-existing structures (especially fracture structures) that serve as boundary conditions.

[0017] (8) Pre-existing structures often possess the attributes of high-level structures. Within a specific mining area, they often manifest as high-level structures that control the entire mining field, and dominantly control the development characteristics of structures and the specific location of rock masses and ore bodies within the mining area.

[0018] (9) Pre-existing structures often have the properties of high-order structures. In later construction activities, the reactivation of pre-existing structures will derive low-order structures of different types and directions.

[0019] (10) Pre-existing structures have different rock-controlling and mineralization-controlling properties. Pre-existing structures are structures that have formed and existed before the occurrence of diagenesis and mineralization. Not all pre-existing structural components have a controlling effect on diagenesis and mineralization. However, pre-existing structural components that play a controlling role in diagenesis and mineralization will inevitably be reactivated, revitalized, or inherited during the diagenesis and mineralization period. Moreover, these structural components are often the parts where their geometric morphology changes.

[0020] (11) Pre-existing structures have the property of preferentially guiding rocks and mineralization. During the diagenetic and mineralization period, pre-existing structures, as existing structures, are favorable transport channels, and the ascent and emplacement of magma and the migration of ore-forming fluids preferentially occur along these structures.

[0021] (12) Pre-existing structures have the property of hosting rocks and ore-gathering. They are often the storage sites that control the shallow positioning of rock masses and the accumulation of ore-forming fluids and ore-forming materials, and transport and migrate ore-forming fluids and ore-forming materials to lower-order or lower-level structures for precipitation and ore formation. The formation of ore bodies also occurs partly along the pre-existing structures.

[0022] Of course, although the aforementioned 12 identifying features of pre-existing structures may not all be developed or reliably identified in the mining areas belonging to the porphyry metallogenic system, combinations of certain identifying features can still effectively identify pre-existing structures. In particular, the aforementioned temporal attributes, reactivation attributes, and complex geometric-kinematic-mechanical properties are often key indicators for identifying pre-existing structures.

[0023] S4: Identify pre-existing structures by integrating the tectonic evolution sequence, the chronological order of formation of structures, ore-forming rock bodies, and ore bodies, and identifying the distinguishing features of pre-existing structures.

[0024] The method of this invention can quickly identify pre-existing structures within porphyry mineralization systems. Based on detailed structural analysis and combined with diagenetic and mineralization isotopic geochronology, it is believed that the formation of pre-existing structures predates the formation of ore-forming rocks and ore bodies, and that they have a significant controlling effect on the formation and distribution of ore-forming rocks and ore deposits (bodies). This method is economical, widely applicable, and has great application potential, providing important evidence for the study of pre-existing structures and the location of ore deposits (bodies) in the field of magmatic hydrothermal deposits. Attached Figure Description

[0025] Figure 1 This describes the fault structure characteristics of a porphyry deposit in northwestern Yunnan.

[0026] Figure 2 Joints and ore-controlling characteristics of a porphyry deposit in northwestern Yunnan;

[0027] Figure 3 The ore-controlling structural grade of a porphyry deposit in northwestern Yunnan;

[0028] Figure 4This is a structural outline map of a porphyry deposit in northwestern Yunnan.

[0029] Figure 5 This represents the tectonic evolution sequence of a porphyry deposit in northwestern Yunnan.

[0030] Figure 6 Determine the diagenetic and mineralization age of a porphyry deposit in northwestern Yunnan;

[0031] Figure 7 The transformation characteristics of the geometry, kinematics, and mechanical properties of pre-existing fractures in a porphyry deposit in northwestern Yunnan.

[0032] Figure 8 This is a high-level and high-order characteristic of pre-existing faults in a porphyry deposit in northwestern Yunnan. Detailed Implementation

[0033] The present invention will be further described in detail below through examples, but the scope of protection of the present invention is not limited to the content described. Unless otherwise specified, the methods in the examples are conventional methods.

[0034] Example 1: The method of the present invention was implemented in a porphyry-type gold polymetallic deposit in northwestern Yunnan Province, and reliable research results were obtained, identifying pre-existing structures. The specific analysis content and technical methods are as follows:

[0035] This deposit is a typical porphyry mineralization system within the Jinshajiang-Ailaoshan alkaline porphyry belt in northwestern Yunnan Province. It features a super-large porphyry-skarn type gold polymetallic deposit (body). The exposed strata in the mining area mainly consist of the Upper Permian, Middle and Lower Triassic, and Cenozoic strata. Magmatic activity in the mining area is primarily Himalayan-era alkaline porphyry, which can be divided into three phases: early-stage quartz-albite porphyry and lamprophyre; middle-stage quartz syenite porphyry and monzogranite porphyry; and late-stage biotite syenite porphyry. The time interval between adjacent magmatic activities is approximately 30 Ma (millions of years). Related studies indicate that the formation and distribution of different phases of rock bodies and ore bodies in this deposit are clearly controlled by tectonic activity.

[0036] S1: Conduct large-scale structural profile measurements at scales of 1:1000 and 1:100-1:200 for parallel and vertical exploration lines on the surface and in open-pit mines, respectively, to analyze the structure of the mining area and classify the tectonic activity periods, compile structural outline maps and construct structural evolution sequences.

[0037] The study analyzes and describes the geometry, involved strata, distribution range, and formation and development process of the folds. The results show that the folds in the mining area are mainly synclines, with secondary anticlines and synclines developing in some local areas. The syncline's axis is nearly north-south, and it is a broad, gently sloping, asymmetrical fold. The involved strata are the Middle and Lower Triassic. Cenozoic strata are distributed in the core of the syncline, with an angular unconformity overlying the Middle Triassic and lower strata. Based on the involved strata and the angular unconformity of the Cenozoic strata overlying the involved strata, and combined with the regional tectonic evolution process, it is determined that the syncline formed under near-east-west compression in the early Himalayas. Within the mining area, the syncline has a north-south length of approximately 6 kilometers and an east-west width of approximately 4 kilometers.

[0038] The study meticulously analyzed the occurrence characteristics, geometric morphology, movement patterns, mechanical property transformation processes, and material composition of fractures and joints. The results show that the mining area has four sets of fractures trending approximately north-south, northeast, northwest, and east-west, exhibiting morphological characteristics such as gentle wavy, mildly wavy, wavy, and serrated patterns. These fractures undergo different mechanical property transformation processes and contain mineralization and alteration phenomena. Figure 1 Meanwhile, the occurrence characteristics, geometric morphology, movement mode, and mechanical properties of the joint structures were analyzed. The results show that the joint structures in the mining area are mainly oriented near north-south, followed by northwest and northeast. Near east-west joints are not well developed. Near north-south joints mainly exhibit extensional characteristics, while northwest and northeast joints mainly exhibit torsional characteristics. Figure 2 ).

[0039] The morphological characteristics, movement patterns, and ore-controlling features of intrusive contact structures were analyzed. The results show that irregularly shaped contact zones often form at the contact points between the rock mass and the surrounding rocks. In addition, contact zones formed by the intrusion of the rock mass along pre-existing fault structures often inherit the morphological characteristics, movement patterns, and mechanical properties of the pre-existing faults.

[0040] Based on the above research, it was determined that the mining area mainly develops a set of fold-fault-joint rock-controlling and ore-controlling structures, including intrusive contact structures, blast breccia pipes, and inter-layer fracture zones. These structures are classified into four levels of ore-controlling structures: ore field structure, ore deposit structure, ore body structure, and vein structure. Figure 3 ), and then a structural outline map of the mining area was compiled ( Figure 4 ).

[0041] Conduct spatial distribution relationships of different types of structures (e.g.) Figure 2Analysis of the mechanical properties and transformation process of the J2-J1 fault in the mining area. The results show that the SN-trending faults in the mining area mainly underwent a mechanical property transformation process of compressive → tensile → left-lateral torsional (compressive) → compressive; the EW-trending faults mainly underwent a mechanical property transformation process of tensile → compressive → right-lateral torsional-compressive → tensile; the NE-trending faults underwent a mechanical property transformation process of right-lateral torsional-compressive → left-lateral torsional-compressive → compressive; and the NW-trending faults underwent a mechanical property transformation process of left-lateral torsional-compressive → right-lateral torsional-compressive → tensile. This reflects that the principal compressive stress in the mining area mainly underwent a transformation process of near-EW → near-SN → NW → near-EW. Figure 5 Based on the complex transformation process of fracture mechanical properties in various directions, and combined with regional tectonic evolution, a tectonic evolution sequence of the mining area is constructed. Figure 5 The sequence is: early north-south tectonic belt → east-west tectonic belt → northeast tectonic belt → late north-south tectonic belt.

[0042] S2: Based on the spatiotemporal distribution patterns of rock masses and ore deposits (bodies) in the region, conduct research on the spatiotemporal distribution patterns of rock masses and ore bodies within the mining area. Compile isotopic age data (U-Pb isotopic age, K-Ar isotopic age, Ar-Ar isotopic age, Re-Os isotopic age, etc.) for different types of rock masses and ore bodies; Figure 6 This study analyzes the chronological order of formation among different types of rock bodies, summarizes the magmatic rock evolution sequence, and, based on the consistency between the diagenetic and mineralization ages, identifies the quartz syenite porphyry and monzogranite porphyry of the Middle Himalayas as mineralized rock bodies. Combining this with the tectonic evolution sequence established in step S1, it preliminarily identifies the early north-south tectonic belts as pre-existing structures, primarily composed of synclines and two sets of main faults trending near SN and near EW. Figure 4 ).

[0043] S3: Based on the pre-existing structures initially identified in step S2, conduct detailed analysis of their geometric morphology, motion patterns, mechanical property transformation processes, and material composition, extracting characteristic markers for identifying pre-existing structures, mainly including the following markers:

[0044] (1) Time markers of pre-existing structures. The aforementioned syncline's involvement in strata and its angular unconformity overlay by Cenozoic strata indicate that the syncline formed in the Early Himalayas; the two sets of main faults trending near SN and near EW cut through the Middle Triassic strata but are covered by Cenozoic strata, indicating that these two sets of faults formed in the Early Himalayas. Figure 4 ).

[0045] (2) The signs of the revival of pre-existing structures and the transformation of complex geometric, kinematic, and mechanical properties. For example... Figure 7As shown, a fault F trending NW is observed at this location, with multiple secondary fault surfaces. The fault surfaces are generally straight and smooth, and two phases of slickensides and quartz stress mineral films are visible on the fault surfaces. The fault zone contains recrystallized porphyry, with the slickensides superimposed on the porphyry. Based on the superposition relationship of the two phases of slickensides, it is determined that the fault successively underwent left-lateral transverse compressional-right transverse compressional-torsional changes. Comprehensive analysis suggests that this fracture exhibits characteristics of three phases of tectonic activity. In the early phase, the principal compressive stress σ1 trended NE-SW, resulting in a compressional-torsional fracture with a potentially gently wavy fracture surface. The hanging wall rose while the footwall subsided. In the middle phase, the principal compressive stress σ1 shifted to EW, transforming the fracture's mechanical properties into left-lateral compressional-torsional fractures. The fracture surface became generally flat and smooth, forming early slickensides (a) and a quartz stress mineral film. The two sides of the fracture primarily experienced left-lateral slip movement in a near-horizontal direction. In the late phase, the principal compressive stress σ1 shifted to a near-SN trend, transforming the fracture's mechanical properties into right-lateral compressional-torsional fractures. Late-phase slickensides (b) formed, superimposed on the early slickensides and the quartz stress mineral film. The hanging wall experienced right-lateral oblique uplift while the footwall subsided obliquely. This point exhibits alteration including silicification and pyrite (later transformed into limonite through oxidation and leaching). Based on the analysis of the ore-controlling structures in the mining area, it is believed that the third phase of tectonic activity in this area is mineralization-stage tectonic activity, accompanied by alteration such as silicification and pyritization; the first and second phases of tectonic activity formed pre-existing structures belonging to the early North-South tectonic belt, which were reactivated in later tectonic activities, exhibiting a complex process of geometric morphology, movement mode, and mechanical property transformation.

[0046] (3) Indicators of high-level, high-order, and boundary effect characteristics of pre-existing structures. For example... Figure 8 As shown, the near-EW trending fault F is a pre-existing fault structure with a wavy fracture surface and a width of about 10 meters, indicating a high-order structure. Several smaller-scale faults and joints are observed on its hanging wall (N-panel), which are constrained by the pre-existing fault F and are low-order structures derived from fault F.

[0047] (4) Indicators of pre-existing structures: priority guiding rocks-mineralization, and host rocks-mineralization (or ore-supporting) rocks. For example... Figure 4 As shown, the near-SN trending faults F1, F3, and F4 on the eastern limb of the syncline in the mining area are pre-existing fault structures. During the diagenetic and mineralization period, these faults became favorable transport channels and storage sites. The emplacement of magma and the migration and accumulation of ore-forming fluids preferentially occurred along these faults, resulting in the near-SN trending distribution of the ore-forming rock mass and ore body. Figure 4 ).

[0048] S4: Based on the above tectonic evolution sequence, the chronological order of formation of tectonics-ore-bearing bodies, and the identifying characteristics of pre-existing structures, the early North-South tectonic belt is identified as a pre-existing structure.

Claims

1. A method for identifying pre-existing structures controlling porphyry mineralization systems, characterized in that, The steps are as follows: S1: Within the porphyry metallogenic system, identify the types, scales, and spatial distribution of structures developed within the mining area, and classify the ore-controlling structures. Conduct structural analysis of the mining area, summarize the occurrence characteristics, geometric features, movement patterns, mechanical properties, and transformation processes of different types of structures, compile a structural outline map of the mining area, and, in conjunction with the spatial distribution of structures and the transformation process of structural mechanical properties, determine the tectonic activity periods and the transformation process of tectonic stress fields, thereby constructing a structural evolution sequence of the mining area. S2: Analyze and determine the petrogenesis and mineralization age of the ore-forming rock mass and ore body, clarify the chronological order of formation between the structure and the ore-forming rock mass and ore body, and preliminarily screen out the pre-existing structures; Organize isotopic age data of different types of rock bodies and ore bodies within the mining area, analyze the evolutionary sequence of different types of rock bodies and the formation age of the ore deposit, or study the sequential intersection relationship between them, and determine the ore-forming rock bodies based on the consistency between the diagenetic age and the metallogenic age; based on the tectonic evolution sequence of the mining area determined in step S1, analyze the temporal and spatial relationship between the structure and the formation and distribution of the ore-forming rock bodies and ore bodies, clarify the chronological order of the formation of the structure and the ore-forming rock bodies and ore bodies, and then preliminarily screen out the pre-existing structures; S3: Conduct detailed analysis of the characteristics of pre-existing structures, including geometric, kinematic, mechanical, material, and chronological features, and extract distinguishing features of pre-existing structures. The specific features and methods are as follows: (1) Pre-existing structures have time-limited attributes: This is the most important indicative attribute of pre-existing structures. Their formation and existence must have preceded the period of diagenesis and mineralization in the porphyry mineralization system. Pre-existing structures can be identified based on the time limit reflected by the stratigraphic position or other marker layers that can reflect geological age, the time limit reflected by the inclusion and cutting relationship between the structure and the rock mass and ore body, the time limit reflected by the composite modification characteristics exhibited by the structure itself and / or the time limit reflected by the cutting, restriction, and merging relationship with other structures. (2) Pre-existing structures have reactivation properties: Pre-existing structures are the weakest zones that are most easily released by stress later. In later tectonic activities, their activation and inheritance development are very common and they are more likely to form than newly formed structures. (3) Pre-existing structures have complex geometric properties: Given the resurrection properties of pre-existing structures, they often exhibit complex geometric features, reflecting the comprehensive morphology formed by the influence of multiple tectonic activities, including tectonic activities during the metallogenic geological period. (4) Pre-existing structures have complex kinematic properties: Given the reactivation properties of pre-existing structures, they often exhibit complex movement patterns, reflecting the comprehensive movement results of multiple tectonic activities; Suppose there is a north-south trending fault F. By analyzing that the fault simultaneously exhibits three movement patterns, namely, hanging wall uplift, relative horizontal slip between the two walls, and hanging wall subsidence, it is clear that the fault is not the product of a single tectonic activity, but rather a movement pattern formed by three tectonic activities; Further suppose that diagenesis and mineralization occurred during the second tectonic activity, then the hanging wall uplift reflects the movement pattern preserved by the pre-existing tectonic activity. (5) Pre-existing structures have complex mechanical properties: Given the reactivation properties of pre-existing structures, they often exhibit complex mechanical property transformation processes, reflecting the different tectonic stress field characteristics of multiple tectonic activities; similarly, taking the north-south trending fault F assumed in "(4) Pre-existing structures have complex kinematic properties" as an example, this fault simultaneously has three movement modes: hanging wall uplift, relative horizontal slip between the two walls, and hanging wall downlift. Under normal circumstances, the mechanical properties reflected by this fault are compressive, torsional, and tensile, which also indicates that this fault is not the product of a single tectonic activity, but rather the mechanical properties and mechanical property transformation processes generated by three tectonic activities. The maximum principal stress σ1 in the horizontal plane reflects the tectonic stress fields of these three tectonic activities as near east-west compression, northwest or northeast compression, and near north-south compression, respectively; similarly, assuming that diagenesis and mineralization occur during the second tectonic activity, then the compressive property reflects the mechanical properties retained by the pre-existing tectonic activity; (6) Pre-existing structures have complex material properties: Given the reactivation properties of pre-existing structures, they often exhibit complex tectonic rock compositions, reflecting the comprehensive results of tectonic rock material compositions generated by multiple tectonic activities; at the same time, the control of pre-existing structures on diagenesis and mineralization varies, with some components of pre-existing structures not contributing to diagenesis and mineralization, while others play a certain role in diagenesis and mineralization; therefore, the tectonic rock composition of non-coalbed-mineralized rocks does not contain the material components of rock bodies and ore bodies, and often does not show traces of hydrothermal alteration or mineralization; while the tectonic rock composition of host rocks and ore bodies will reflect the material components of rock bodies and ore bodies, and often has a certain degree of hydrothermal alteration or mineralization. (7) Pre-existing structures have boundary effect properties: When pre-existing structures are active, they will develop different structural traces and produce different structural combination patterns due to the influence of different types and directions of pre-existing structures, especially fracture structures, which serve as boundary conditions. (8) Pre-existing structures often have the attributes of high-level structures: within a specific mining area, they often manifest as high-level structures that control the entire mining field, and dominate the development characteristics of structures within the mining area and the specific location of rock masses and ore bodies. (9) Pre-existing structures often have the property of high-order structures: In later construction activities, the re-activity of pre-existing structures will derive low-order structures of different types and directions. (10) Pre-existing structures have different rock-controlling and mineralization-controlling properties: Pre-existing structures are structures that have formed and existed before the occurrence of diagenesis and mineralization. Not all pre-existing structural components have a controlling effect on diagenesis and mineralization. However, pre-existing structural components that play a controlling role in diagenesis and mineralization will inevitably be revived, activated or inherited during the diagenesis and mineralization period. Moreover, these structural components are often the parts where their geometric morphology changes. (11) Pre-existing structures have the property of preferentially guiding rocks and mineralization: during the diagenetic and mineralization period, pre-existing structures, as existing structures, are favorable transport channels, and the ascent and emplacement of magma and the migration of ore-forming fluids preferentially occur along these structures. (12) Pre-existing structures possess the properties of hosting rocks or minerals; It is often the storage site that controls the shallow positioning of the rock mass and the accumulation of ore-forming fluids and ore-forming materials, and transports and migrates the ore-forming fluids and ore-forming materials to lower-order or lower-level structures for precipitation and mineralization. The formation of the ore body also occurs partly along the pre-existing structure. S4: By integrating the tectonic evolution sequence, the chronological order of formation of tectonic-ore-forming rock bodies and ore bodies, and the identification characteristics of pre-existing structures, the pre-existing structures controlling the porphyry mineralization system can be identified.

2. The method for identifying pre-existing structures controlling porphyry mineralization systems according to claim 1, characterized in that: The distinguishing features of pre-existing structures include time-limited attributes, reactivation attributes, complex geometric attributes, complex kinematic attributes, complex mechanical properties, complex material properties, boundary effect attributes, attributes of higher-level structures, attributes of higher-order structures, differential rock- and ore-controlling attributes, preferential rock- and ore-controlling attributes, and rock- and ore-hosting attributes.

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