Method for positioning concealed ore-forming rock mass and ore body in porphyry ore-forming system by using pre-existing structure

Abstract

The present application relates to a kind of methods for positioning concealed ore-forming rock mass and ore body in porphyry metallogenic system using pre-existing structure, which comprises the following steps: carrying out fine analysis of ore district ore-controlling structure and analysis of the order of generation of structure-ore-forming rock mass-ore body, identifying pre-existing structure; analyzing the time and spatial distribution characteristics of ore district ore-forming rock mass and ore body, and finding out the time and spatial distribution law of ore-forming rock mass and ore body; analyzing the spatial distribution relationship of pre-existing structure-ore-forming rock mass-ore body, extracting qualitative indicators for spatial positioning of pre-existing structure indicating ore-forming rock mass and ore body; constructing pre-existing structure rock-controlling and ore-controlling model, and determining the spatial positioning of concealed ore-forming rock mass and ore body; the method solves the problem of quickly determining the spatial positioning of concealed ore-forming rock mass and ore body in the process of diagenesis and mineralization in porphyry metallogenic system, not only provides an effective method for deep prospecting prediction, but also provides an important basis for deep exploration engineering layout in the prediction area.

Description

Technical Field

[0001] This invention relates to a method for locating concealed ore-forming rock bodies and ore bodies using pre-existing structures within a porphyry mineralization system, belonging to the field of magmatic hydrothermal deposit exploration technology. Background Technology

[0002] my country is a major consumer and producer of mineral resources. In recent decades, many large and super-large mines have seen their shallow resources gradually depleted during resource development. Therefore, searching for alternative resources at deeper levels in known mining areas (deposits) and constructing a theoretical and technical methodology system for deep resource exploration has become an inevitable choice for ensuring my country's resource security and promoting high-quality development of the mining economy. Deposits related to porphyry mineralization (porphyry-type deposits, epithermal deposits, etc.) are major sources of many precious, non-ferrous, and rare metals worldwide, such as gold, silver, copper, molybdenum, lead, zinc, rhenium, selenium, and tellurium. These deposits are characterized by uniform mineralization grades, huge ore quantities, shallow ore bodies, diverse mineral types, suitability for large-scale mining, and significant potential for exploration in the deep periphery. Currently, mature exploration techniques for the deep periphery of these deposits have not yet been developed.

[0003] Tectonic activity is one of the key factors controlling the formation and distribution of almost all types of mineral deposits. Pre-existing structures (structures that formed and existed before the metallogenic geological period) serve as a favorable tectonic setting, tectonic driving force, and ore-hosting space for mineralization. They can organically link the two core issues of ore-forming fluid migration ("migration") and ore-forming material storage ("reservoir") in the "source-migration-reservoir" mineralization process. Pre-existing structures are widely developed in porphyry metallogenic systems and have unique rock-controlling and ore-controlling effects.

[0004] Furthermore, in traditional mineral exploration, it is common practice to use ore-forming and post-ore-forming structures to determine and evaluate the spatial location of ore deposits, as well as the changes and preservation of ore deposits after mineralization. Related research has provided important evidence for finding concealed ore deposits. The emphasis on the formation process and changes and preservation of ore deposits focuses on the ore-controlling effects of ore-forming and post-ore-forming structures, often neglecting the controlling role of pre-existing structures in the formation and distribution of ore deposits. Therefore, traditional research on the tectonic control of ore deposits is insufficient to effectively determine the occurrence characteristics and spatial variation patterns of deep concealed ore-forming rock bodies and ore deposits (bodies), leading to difficulties in effectively extracting deep mineralization information and often resulting in inefficient deep mineral exploration.

[0005] Therefore, in the urgent task of finding deep replacement resources, how to effectively and quickly conduct comprehensive evaluation of deep mineral resources has become a research frontier in the geosciences. Thus, it is necessary to propose an effective exploration technique to rapidly evaluate the resource potential of deep porphyry metallogenic systems. Summary of the Invention

[0006] To address the technical challenge of rapidly determining the spatial location of concealed ore-forming rock masses and ore bodies within porphyry metallogenic systems, this invention provides a method for locating concealed ore-forming rock masses and ore bodies using pre-existing structures within the porphyry metallogenic system. This method, based on the identification of pre-existing structures, clarifies the spatiotemporal distribution patterns of ore-forming rock masses and ore bodies, identifies the spatial distribution relationship between pre-existing structures, ore-forming rock masses, and ore bodies, extracts qualitative indicators from pre-existing structures that indicate the spatial location of ore-forming rock masses and ore bodies, constructs a model of rock and ore control by pre-existing structures, and ultimately determines the spatial location of concealed ore-forming rock masses and ore bodies.

[0007] The method for locating concealed ore-forming rock bodies and ore bodies using pre-existing structures within a porphyry mineralization system is as follows:

[0008] I. Identification of Pre-existing Structures

[0009] 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 following characteristics and their transformation processes (direction and dip angle), geometric features (width, extension, depth, and structural surface morphology—straight, serrated, wavy, gently wavy, gradually wide and steeply narrow, etc.), movement patterns (leftward or rightward movement in a plane; upward or downward movement in a 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.

[0010] 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;

[0011] We will compile 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 within the mining area, analyze the evolutionary sequence of different types of rock bodies and the formation age of ore bodies, and determine the ore-forming rock bodies based on the consistency between the diagenetic age and the mineralization age; based on the tectonic evolution sequence of the mining area determined in step S1, we will analyze the temporal and spatial relationship between the formation and distribution of ore-forming rock bodies and ore bodies, clarify the chronological order of formation between the tectonic structure and the ore-forming rock bodies and ore bodies, and then preliminarily screen out the pre-existing structures;

[0012] S3: For the pre-existing structures initially identified in step S2, conduct a detailed analysis of their characteristics, including geometric, kinematic, mechanical, material, and chronological features, and extract the identifying features of the pre-existing structures. The specific features and methods are as follows:

[0013] (3-1) 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 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 relationships with other structures.

[0014] (3-2) Pre-existing structures have reactivation properties. Pre-existing structures are the weakest zones most easily released by subsequent stress. Their activation and inheritance are very common in later tectonic activities and are more likely to form than newly formed structures.

[0015] (3-3) 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.

[0016] (3-4) Pre-existing structures possess complex kinematic properties. Given the reactivation properties of pre-existing structures, they often exhibit complex movement patterns, reflecting the combined results of multiple tectonic activities. Assuming the existence of a north-south trending fault F, analysis reveals three movement patterns simultaneously: hanging wall uplift, relative horizontal slip between the two walls, and hanging wall subsidence. This indicates that the fault is not a product of a single tectonic activity, but rather a result of three distinct tectonic activities. Further assuming that diagenesis and mineralization occurred during the second phase of this tectonic activity, then the hanging wall uplift reflects a movement pattern preserved from the pre-existing tectonic activity.

[0017] (3-5) 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 hypothetical north-south trending fault F from "(3-4) 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. Furthermore, the tectonic stress fields (based on the maximum principal stress σ1 in the horizontal plane) of these three tectonic activities are respectively near-east-west compression, northwest or northeast compression, and near-north-south compression. 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 activity.

[0018] (3-6) 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, often exhibiting a certain degree of hydrothermal alteration or mineralization.

[0019] (3-7) 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.

[0020] (3-8) Pre-existing structures often possess the attributes of high-level structures. Within a specific mining area, they often manifest as high-level structures controlling the entire mining field, and dominating the development characteristics of structures and the specific location of rock masses and ore bodies within the mining area.

[0021] (3-9) Pre-existing structures often possess 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.

[0022] (3-10) 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.

[0023] (3-11) Pre-existing structures have the property of preferentially guiding rock 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;

[0024] (3-12) Pre-existing structures have the property of hosting rocks and ore-bearing. 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 pre-existing structures.

[0025] S4: By integrating the tectonic evolution sequence, the chronological order of formation of tectonics-ore-forming rock bodies-ore bodies, and the identification characteristics of pre-existing structures, the pre-existing structures controlling the porphyry mineralization system are identified;

[0026] II. Spatial Location of Concealed Ore-forming Rock Masses and Ore Bodies

[0027] S1: Investigate the types, occurrence characteristics, and spatial distribution of ore-forming rock masses and ore bodies in the mining area, and conduct research on the spatiotemporal distribution patterns of ore-forming rock masses and ore bodies within the mining area.

[0028] Based on step S2, identify the ore-forming rock bodies; summarize the morphological, scale, and occurrence characteristics of different types and phases of rock bodies, including length, width, strike, dip, and retraction, and clarify their occurrence morphological characteristics and spatial distribution relationships; identify the ore body types, summarize the morphological, scale, and occurrence characteristics of different types of ore bodies, including length, width, strike, dip, and retraction, and summarize their spatial occurrence patterns; analyze the temporal and spatial relationships between the formation and distribution of ore-forming rock bodies and ore bodies, and clarify the temporal and spatial distribution patterns of ore-forming rock bodies and ore bodies within the mining area;

[0029] S2: Based on the pre-existing structures identified in Step 1 and the spatiotemporal distribution patterns of ore-forming rock masses and ore bodies obtained in Step 2 (S1), analyze the relationship between the characteristics of the pre-existing structures, such as their occurrence, geometric shape, movement mode, and mechanical property transformation process, and the spatial distribution of ore-forming rock masses and ore bodies in the plane and profile. Extract qualitative indicators of the pre-existing structures that indicate the spatial location of ore-forming rock masses and ore bodies, so as to serve as the basis for evaluating the spatial location of concealed ore-forming rock masses and ore bodies in the deep and marginal parts of the mining area.

[0030] The specific qualitative indicators and methods for locating ore-forming rock masses and ore bodies based on existing structural features are as follows:

[0031] (2-1) Types of Pre-existing Structures. Within porphyry mineralization systems, pre-existing high-level structures often play a significant role in controlling the shallow emplacement of magma and the insitu placement of ore deposits (bodies). The most common types of high-level structures are folds and faults. For pre-existing fold structures, it is necessary to first identify the type of pre-existing fold (syncline or anticline) controlling the mining area; secondly, analyze and summarize the spatial distribution patterns of rock masses and ore bodies controlled by pre-existing folds. Generally speaking, the core of a pre-existing fold is more likely to form fracture spaces than its limbs. Therefore, the core of a pre-existing fold is often the location where ore-forming rock masses and ore bodies are distributed. In addition, the core of a syncline is more conducive to shallow magma emplacement than the core of an anticline, while the accumulation of ore-forming fluids is often the opposite, that is, ore bodies are more likely to be insitu in the core of an anticline. For pre-existing fault structures, magma intrusion and ore body emplacement often occur directly along these faults. Therefore, one can locate rock masses and ore bodies by "following the map" along these pre-existing faults. Simultaneously, the confluence of pre-existing faults in different directions is usually an important location for later magma intrusion and ore body emplacement. Within specific porphyry mineralization systems, there are often confluences of pre-existing folds and faults, which may have formed at the same or different times. In addition to the above analysis and research, it is also necessary to pay attention to the rock-controlling and ore-controlling effects of the confluence of these two types of faults.

[0032] (2-2) Occurrence characteristics of pre-existing structures. Based on identifying the types of pre-existing structures controlling the mining area, analyzing and clarifying the occurrence characteristics of these structures is crucial for guiding the spatial location of concealed ore-forming rock masses and ore bodies. For pre-existing folds, it is necessary to analyze their strike (axial direction), axial plane and limb occurrence, hinge occurrence, etc., to focus on clarifying the horizontal extension direction, axial plane spatial configuration (location and morphology), dip azimuth, and dip angle of the pre-existing folds. These characteristics will directly control the occurrence morphology and spatial distribution of rock masses and ore bodies. For example, in a pre-existing anticline trending approximately SN (horizontal extension of the fold), dipping E at a 60° dip angle (the axial plane dips towards E, and the dip angle of the axial plane is 60°), and plunging N at a 30° plunging angle (the hinge dips towards N, and the plunging angle is 30°), the ore-forming rock mass or ore body controlled by its core often also extends approximately SN, dips E, and plunges N. The concealed ore-forming rock mass or ore body is often distributed deep within the plunging end (deep within the 30° plunging angle plunging towards N). For pre-existing faults, their strike, dip, and dip angle must be determined. Since the ore-forming rock mass and ore body directly emplace and emplace along the pre-existing fault, their occurrence morphology and distribution characteristics can often be directly obtained by analyzing the occurrence of the pre-existing fault.

[0033] (2-3) Geometric morphological indicators of pre-existing structures. Pre-existing structures often exhibit complex geometric morphological characteristics due to the influence of multiple tectonic activities, including those during the metallogenic geological period. In particular, pre-existing faults are the most typical and common. The locations where the geometric morphology of these faults undergoes complex transformations, such as from steep and closed to gentle and open, or from straight and smooth to wavy (serrated) bends, are often the locations where ore-forming rock masses and / or ore bodies are located.

[0034] (2-4) Indicators of the Movement Patterns of Pre-existing Structures. Pre-existing structures often exhibit complex movement patterns. The movement patterns of pre-existing structures during their reactivation in the mineralization period can indicate the spatial location of ore-forming rock masses and / or ore bodies. The movement patterns of faults are mainly manifested in three ways: uplift of the hanging wall and subsidence of the footwall; subsidence of the hanging wall and uplift of the footwall; and relative horizontal slip between the two walls. Generally speaking, pre-existing faults exhibit these three movement patterns during the mineralization period, which can respectively indicate the main distribution of ore-forming rock masses and ore bodies within: the fault and its hanging wall; the fault and its footwall; and the fault itself. Taking a pre-existing fault with a near-SN trend, dipping E, and dip angle of 60° as an example, analysis shows that this fault exhibits three movement modes simultaneously: hanging wall uplift, hanging wall right-lateral oblique thrust, and hanging wall subsidence, indicating that it is a movement mode formed by three phases of tectonic activity. Assuming that diagenesis and mineralization occurred during the second phase of tectonic activity, then magma and ore-forming fluids often migrate and accumulate along this fault from N to S and from deep to shallow. Ore-forming rock bodies and ore bodies are mainly formed and distributed in the hanging wall of this fault, while concealed ore-forming rock bodies and ore bodies are often distributed in the deep part of the fault extending towards the N side.

[0035] (2-5) Mechanical Properties and Transformation Process Indicators of Pre-existing Structures. Pre-existing structures often possess complex mechanical properties and transformation processes. Pre-existing structures that play a controlling role in diagenesis and mineralization inevitably undergo mechanical property transformations during the mineralization geological period. The mechanical properties and transformation processes of pre-existing structures can reflect their complex geometric morphology and movement characteristics, thereby indirectly indicating the spatial location of ore-forming rock masses and ore bodies, as shown in "(2-3) Geometric Morphology Indicators of Pre-existing Structures" and "(2-4) Movement Mode Indicators of Pre-existing Structures" above. The mechanical properties of fractures are mainly manifested in three types: compressive; tensile; and torsional. Generally speaking, these three mechanical properties correspond to the fracture movement modes of "hanging wall rising, footwall falling; hanging wall falling, footwall rising; relative horizontal slippage between the two walls" in "(2-4) Movement Mode Indicators of Pre-existing Structures", thus indirectly indicating the spatial location of ore-forming rock masses and ore bodies.

[0036] Of the five qualitative indicators mentioned above for the location of ore-forming rock masses and ore bodies, the most important are the type, occurrence characteristics, geometric shape, and movement mode of the pre-existing structures. The mechanical properties of the pre-existing structures and their transformation process often indirectly indicate the spatial location of ore-forming rock masses and ore bodies.

[0037] S3: Integrating the spatial distribution relationship between pre-existing structural features and ore-forming rock bodies and ore bodies, and combining the extracted qualitative indicators of the spatial location, occurrence characteristics, geometric morphology, movement mode and mechanical properties of ore-forming rock bodies and ore bodies, as well as their transformation processes, a pre-existing structural rock-controlling and ore-controlling model is constructed. Based on this model and the known distribution characteristics of ore-forming rock bodies and ore bodies, the spatial location of concealed ore-forming rock bodies and ore bodies in the deep and marginal parts of the mining area is comprehensively determined.

[0038] This invention reveals that the method can quickly determine the spatial location of concealed ore bodies and mineralization bodies in porphyry mineralization systems, effectively reducing exploration costs and improving the prospecting efficiency of deep concealed ore bodies. Pre-existing structures during the metallogenic geological period controlled the formation and distribution of ore bodies and mineralization bodies.

[0039] Advantages and technical effects of the method of the present invention:

[0040] (1) This method can achieve qualitative evaluation of the spatial orientation of deep and edge concealed ore-forming rock masses and ore bodies;

[0041] (2) This method can identify the location patterns of hidden ore-forming rock masses and ore bodies in the deep and marginal parts of the mining area, thereby improving the efficiency of mineral exploration.

[0042] (3) This method is relatively simple and easy to apply and promote. Especially in the prospecting stage where the research level is not high, it can quickly determine the location of the hidden ore-forming rock mass and the ore body, thereby significantly shortening the prospecting cycle and significantly reducing the prospecting cost.

[0043] (4) This method can provide a scientific basis for the deployment of deep exploration projects and improve the construction cycle and development efficiency of mines. Attached Figure Description

[0044] Figure 1 This is a schematic flowchart of the method of the present invention;

[0045] Figure 2 This describes the fault structure characteristics of a porphyry deposit in northwestern Yunnan.

[0046] Figure 3 Joints and ore-controlling characteristics of a porphyry deposit in northwestern Yunnan;

[0047] Figure 4 The ore-controlling structural grade of a porphyry deposit in northwestern Yunnan;

[0048] Figure 5 This is a structural outline map of a porphyry deposit in northwestern Yunnan.

[0049] Figure 6 This represents the tectonic evolution sequence of a porphyry deposit in northwestern Yunnan.

[0050] Figure 7Determine the diagenetic and mineralization age of a porphyry deposit in northwestern Yunnan;

[0051] Figure 8 The transformation characteristics of the geometry, kinematics, and mechanical properties of pre-existing fractures in a porphyry deposit in northwestern Yunnan.

[0052] Figure 9 This is a high-level and high-order characteristic of a pre-existing fault in a porphyry deposit in northwestern Yunnan.

[0053] Figure 10 A simplified diagram of the spatiotemporal characteristics of a porphyry deposit in northwestern Yunnan.

[0054] Figure 11 A simplified diagram of the ore body characteristics of a porphyry deposit in northwestern Yunnan.

[0055] Figure 12 Spatial distribution characteristics of ore bodies in a porphyry deposit in northwestern Yunnan;

[0056] Figure 13 This describes the pre-existing fault-controlled ore-bearing characteristics of a porphyry deposit in northwestern Yunnan.

[0057] Figure 14 This is a model of the pre-existing tectonic rock-controlling and ore-controlling structure of a porphyry deposit in northwestern Yunnan. Detailed Implementation

[0058] 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.

[0059] Example: Figure 1 As shown, the method of this invention was implemented in a porphyry gold polymetallic deposit in northwestern Yunnan. It not only provided important scientific basis for mineral exploration and prediction in the deep and peripheral parts of the mining area, but also achieved reliable research results, the specific contents of which are as follows.

[0060] This deposit is a typical porphyry mineralization system within the Jinshajiang-Ailaoshan alkaline porphyry belt in northwestern Yunnan, featuring a super-large porphyry-skarn type gold polymetallic deposit (body). The magmatic activity in the mining area is primarily Himalayan-era alkaline porphyry. The formation of the deposit is closely related to magmatism; the ore-forming fluids and ore-forming materials originated from magma. Common ore minerals include molybdenite, chalcopyrite, pyrite, pyrrhotite, magnetite, sphalerite, galena, native gold, and native silver. Gangue minerals are mainly quartz, garnet, pyroxene, amphibole, epidote, chlorite, feldspar, and calcite. Related studies indicate that the formation and distribution of different phases of the rock bodies and ore bodies in this deposit are clearly controlled by tectonic activity.

[0061] I. Identification of Pre-existing Structures

[0062] 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.

[0063] 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.

[0064] 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 2 Simultaneously, the occurrence characteristics, geometric morphology, movement mode, and mechanical properties of joint structures are analyzed. Figure 3 The results showed that the joint structures in the mining area were mainly oriented near north-south, followed by northwest and northeast. Near east-west joints were not well developed. Near north-south joints mainly exhibited extensional characteristics, while northwest and northeast joints mainly exhibited torsional characteristics.

[0065] 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.

[0066] 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 4 ), and then a structural outline map of the mining area was compiled ( Figure 5 ).

[0067] 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 6 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, which is: Early North-South Tectonic Belt → East-West Tectonic Belt → Northeast Tectonic Belt → Late North-South Tectonic Belt. Figure 6 ).

[0068] 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 7 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. Combined with the tectonic evolution sequence of the mining area established in step S1, the early north-south tectonic belts are pre-existing structures, mainly composed of synclines and two sets of main faults trending near SN and near EW. Figure 5 ).

[0069] 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:

[0070] (3-1) 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 5 ).

[0071] (3-2) The signs of the revival of pre-existing structures and the transformation of complex geometric, kinematic, and mechanical properties. For example... Figure 8As 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 ascent 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.

[0072] (3-3) Indicators of high-level, high-order, and boundary effect characteristics of pre-existing structures. For example... Figure 9 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.

[0073] (3-4) Indicators of pre-existing structures: preferential guiding rocks-ore-guiding rocks, and host rocks-combining (hosting) rocks. For example... Figure 3 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 5 ).

[0074] S4: Based on the above 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 early North-South tectonic belt is identified as a pre-existing structure.

[0075] II. Spatial Location of Concealed Ore-forming Rock Masses and Ore Bodies

[0076] S1: By compiling the U-Pb, K-Ar isotopic ages of different types of rock bodies and the Re-Os isotopic ages of ore bodies in the mining area, a distribution map of the diagenetic and mineralization ages of the rock bodies and ore bodies in the mining area was obtained. Figure 7 An evolutionary sequence of different types of rock bodies was established: Early Himalayan rock was composed of quartz-albite porphyry and lamprophyre; Middle Himalayan rock was composed of quartz syenite porphyry and monzogranite porphyry; Late Himalayan rock was composed of biotite syenite porphyry. The time interval between adjacent magmatic events was approximately 30 Ma (millions of years). The morphological, scale, and occurrence characteristics of different types and phases of rock bodies were summarized, including length, width, strike, dip, and lateral strike. Figure 10 The study investigated their occurrence morphology and spatial distribution relationships—rock masses from different periods mainly occurred in the form of stocks, dikes, or dykes, varying in size, with dominant extension directions of SN or EW, and different dips, often at relatively large angles. Figure 10 Five types of ore bodies were identified in the mining area: porphyry, skarn, hydrothermal vein, siliceous-calcium surface, and oxidative leaching enrichment. The first four types are genetically linked to the ore-forming rock masses and are products of the porphyry mineralization system. The last type represents changes and modifications to previous ore bodies after mineralization and is not a product of the porphyry mineralization system, but rather a product of the oxidative leaching mineralization system. The morphology, scale, and occurrence characteristics of the different types of ore bodies, including length, width, strike, dip, and lateral displacement, were summarized. Figure 11 The spatial occurrence patterns can be summarized as follows: Porphyry ore bodies are hosted within the ore-forming rock mass, with a dominant extension direction of SN (southeast-northeast). Individual ore bodies or veins often have large dip angles and mainly occur as veins or disseminated veins. Skarn ore bodies are mainly hosted at the contact zone between the ore-forming rock mass and the surrounding rock. The length and thickness of the ore body vary, with near-SN extension being the dominant direction. They mainly occur as stratiform, vein-like, lenticular, or irregular shapes. Hydrothermal vein ore bodies are hosted within the surrounding rock outside the ore-forming rock mass. The length and thickness of the ore body vary, with near-SN or NE extension being the dominant direction. The dip angles vary, and they mainly occur as veins or lenticular shapes. Silicate-calcium planar ore bodies are hosted within the surrounding rock outside the ore-forming rock mass. The length and thickness of the ore body vary, with near-SN or NE extension being the dominant direction. The dip angles are relatively small, and they mainly occur as stratiform or lenticular shapes. Figure 12 Furthermore, the temporal and spatial relationships between the formation and distribution of ore-forming rock masses and ore bodies are analyzed, and the spatiotemporal distribution patterns of ore-forming rock masses and ore bodies in the mining area are summarized—the ore bodies that make up the porphyry mineralization system and the ore-forming rock masses are consistent in time. Figure 7 Spatially, porphyry ore bodies are hosted within the ore-forming rock mass, skarn ore bodies are mainly hosted at the contact zone between the ore-forming rock mass and the surrounding rocks, and hydrothermal vein-type and siliceous-calcium-faced ore bodies are hosted within the surrounding rocks surrounding the ore-forming rock mass, reflecting the inseparable spatial distribution of ore bodies and ore-forming rock masses. Figure 12 ).

[0077] S2: Based on the pre-existing structures identified in Step 1 and the spatiotemporal distribution patterns of ore-forming rocks and ore bodies summarized in Step 2 (S1), analyze the spatial distribution relationship between pre-existing structures and ore-forming rocks and ore bodies in plan and profile, and extract qualitative indicators of pre-existing structures that indicate the location of ore-forming rocks and ore bodies; see Figure 13 The inner ore body occurs in plan view on a pre-existing fault F1 that is nearly north-south trending, dips westward, and is steeply dipping (see plan view location). Figure 5 Within the fracture zone (pre-existing structural characteristics), the serrated nature of the fracture, the "gentle-wide, steep-narrow" sections (pre-existing structural geometric characteristics), the footwall of the fracture (left-lateral descent on the hanging wall, left-lateral thrust on the footwall; pre-existing structural movement patterns), and the transition from compressive to extensional-torsional fractures (compressive before mineralization, extensional-torsional during mineralization; the transformation process of pre-existing structural mechanical properties), the ore body generally exhibits an equidistant distribution pattern of "expansion-shrinkage" and "pincerization and reappearance" in plan view. In cross-section, the ore-forming rock mass and ore body occur along the pre-existing fracture, exhibiting a westward, steeply dipping, and northward-lateral distribution pattern with equal depth intervals. These characteristics can serve as qualitative indicators for evaluating the spatial location of concealed ore-forming rock masses and ore bodies in the deep and peripheral blank areas.

[0078] S3: Integrating the spatial distribution relationship between pre-existing tectonic features and ore-forming rocks and ore bodies, and combining the extracted qualitative indicators of the occurrence characteristics, geometric morphology, movement mode, and mechanical property transformation process of pre-existing tectonic features indicating the spatial location of ore-forming rocks and ore bodies, a pre-existing tectonic rock-forming and ore-forming model is constructed. Figure 14 Based on the model and known distribution characteristics of ore-forming rock bodies and ore bodies, the morphology and occurrence location of concealed ore-forming rock bodies and ore bodies in the deep and marginal parts of the mining area are comprehensively determined. Finally, the concealed ore-forming rock bodies and ore bodies are located in the core of the existing syncline and the areas where existing SN-trending faults are developed on both flanks of the syncline. These are favorable potential occurrence locations for concealed ore-forming rock bodies and ore bodies.

Claims

1. A method for locating concealed ore-forming rock bodies and ore bodies using pre-existing structures within a porphyry mineralization system, characterized in that, Includes the following steps: I. Identification of Pre-existing Structures 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; The isotopic age data of different types of rock bodies and ore bodies in the mining area are collected, namely U-Pb isotopic age, K-Ar isotopic age, Ar-Ar isotopic age, and Re-Os isotopic age. The evolutionary sequence of different types of rock bodies and the formation age of ore bodies are analyzed. The ore-forming rock bodies are determined based on the consistency between the diagenetic age and the mineralization age. Based on the tectonic evolution sequence of the mining area determined in step S1, the temporal and spatial relationship between the structure and the formation and distribution of the ore-forming rock bodies and ore bodies is analyzed. The chronological order of formation between the structure and the ore-forming rock bodies and ore bodies is determined, and the pre-existing structures are preliminarily screened out. S3: Conduct detailed analysis of the characteristics of pre-existing structures, analyze the geometric, kinematic, mechanical, material, and chronological features of pre-existing structures, and extract the distinguishing features of pre-existing structures; (3-1) Pre-existing structures have a time limit attribute, which is the most important indicative attribute of pre-existing structures. Their formation and existence must precede the occurrence 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. (3-2) Pre-existing structures have the property of reactivation. Pre-existing structures are the weakest zones that are most likely to be 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. (3-3) Pre-existing structures have complex geometric properties. Given the resurrection properties of pre-existing structures, they often exhibit complex geometric morphological features, reflecting the comprehensive morphology formed by the influence of multiple tectonic activities, including tectonic activities during the metallogenic geological period. (3-4) 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. Assuming there is 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 tectonic activities. Furthermore, assuming 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. (3-5) Pre-existing structures have 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 "(3-4) Pre-existing structures have 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 as near-east-west compression, northwest or northeast compression, and near-north-south compression, with the maximum principal stress σ1 in the horizontal plane as the standard. 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. (3-6) 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 the tectonic rock material composition generated by multiple phases of tectonic activity. At the same time, the control of pre-existing structures on diagenesis and mineralization varies. Some components of pre-existing structures do not contribute 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. However, 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. (3-7) 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. (3-8) 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 and the specific location of rock masses and ore bodies within the mining area. (3-9) Pre-existing structures often have the property of high-order structures. In later construction activities, the reactivation of pre-existing structures will derive low-order structures of different types and directions. (3-10) 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. (3-11) 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. The ascent and emplacement of magma and the migration of ore-forming fluids preferentially occur along these structures. (3-12) Pre-existing structures have the properties of hosting rocks and minerals. 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. They transport and migrate ore-forming fluids and ore-forming materials to lower-order or lower-level structures for precipitation and mineralization. The formation of ore bodies also occurs partly along pre-existing structures. 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 are identified; II. Spatial Location of Concealed Ore-forming Rock Masses and Ore Bodies S1: Investigate the types, occurrence characteristics, and spatial distribution characteristics of ore-forming rock masses and ore bodies in the mining area, and summarize the temporal and spatial distribution patterns of ore-forming rock masses and ore bodies; S2: Analyze the spatial distribution relationship between pre-existing structures, ore-forming rock masses, and ore bodies, and extract qualitative indicators of pre-existing structures that indicate the location of ore-forming rock masses and ore bodies; S3: By integrating the spatial distribution relationship between pre-existing structures, ore-forming rock bodies, and ore bodies, and the qualitative indicators of pre-existing structures indicating the spatial location of ore-forming rock bodies and ore bodies, a pre-existing structure-controlled rock and ore model is constructed to determine the spatial location of concealed ore-forming rock bodies and ore bodies.

2. The method for locating concealed ore-forming rock bodies and ore bodies using pre-existing structures within a porphyry mineralization system, as described in claim 1, is characterized in that: Qualitative indicators for the spatial location of ore-forming rock masses and ore bodies based on pre-existing structures include indicators of the type of pre-existing structures, indicators of occurrence characteristics, indicators of geometric morphology, indicators of movement patterns, indicators of mechanical properties and their transformation processes.

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