Method and product for the analysis of isopach-stress field-geological structure

Abstract

The present application relates to the field of earth science, specifically relates to a method and product for isopach-stress field-geological structure analysis of the crust, the method comprising determining stratum layered structure and establishing a physical parameter model, the layered structure comprising a crust layer, a plastic layer and a magma layer; based on the change of the magma density gradient, a magma flow model is constructed to analyze the laminar flow characteristics and the flow velocity distribution in the crust thickness variation area; combined with the regional crust thickness contour map, the stress field distribution of magma flow in different crust thickness areas and its driving effect on fracture tectonic activity are analyzed, and the dynamic coupling relationship between magma flow and fracture tectonic activity is obtained; the present application can provide an accurate basis for the analysis of the influence of magma flow on crustal tectonic activity. The flow model established based on the change of the magma density gradient determines the flow characteristics and flow velocity distribution characteristics of the magma layer, especially the complex flow behavior in the crust thickness variation area.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of earth science, in particular to an analysis method and product for crustal isopach-stress field-geological structure. BACKGROUND

[0002] The dynamic source and mechanism of crustal tectonic activity is an important research field of earth science, which covers the movement law of crustal plate, the flow characteristics of magma layer and its coupling with crustal tectonic activity. Since the plate tectonics theory was proposed, it has become the core theory for explaining the crustal movement and related geological phenomena. Based on the physical phenomena such as mantle convection, crustal thickness distribution and magmatic activity, the theory establishes a basic framework for describing the crustal activity.

[0003] At present, scientists have carried out extensive research on the dynamic characteristics of crustal movement by combining theoretical research and experimental observation. For example, through the geophysical detection technology such as seismic wave propagation characteristics and gravity measurement, the deep structure of crust and mantle is studied, which provides rich data support for the research on the dynamic mechanism of crustal tectonic activity. In addition, based on the crustal isostatic theory and the density gradient model, the stress field distribution law caused by magma flow is further discussed, and the regional crustal dynamics behavior is predicted and analyzed combined with regional fault tectonic activity.

[0004] Although there have been many research results, the dynamic mechanism of crustal tectonic activity is still a mystery, especially in the coupling of magma flow and crustal tectonic activity. For example, the influence of crustal thickness on the flow characteristics of magma has not yet formed a unified understanding, and the stress field distribution and evolution law in different tectonic units also lack systematic description. Therefore, it is of great scientific significance and application value to further explore the influence mechanism of magma flow on the stress field distribution of crust and fault tectonic activity. SUMMARY

[0005] The technical problem to be solved by the present application is how to accurately analyze the influence of magma flow on crustal tectonic activity and its coupling mechanism, and the purpose is to provide an analysis method and product for crustal isopach-stress field-geological structure, which realizes the comprehensive revelation of the mutual relationship between magma flow and regional stress field distribution, fault tectonic activity through layered modeling and quantitative analysis, so as to provide scientific basis for the prediction of crustal tectonic activity and the prevention and control of geological disasters.

[0006] The present application is realized by the following technical scheme:

[0007] An analysis method for crustal isopach-stress field-geological structure, comprising:

[0008] determining the layered structure of crustal layer, plastic layer and magma layer, and establishing the physical parameter model of each layer;

[0009] Based on the change of the magma density gradient, a magma laminar flow model is constructed to analyze the laminar flow characteristics of the magma and the flow velocity distribution of the magma in the thick and thin areas of the crust;

[0010] In combination with the regional crust thickness contour map, the influence of the magma flow on the stress field distribution in different thick and thin areas of the crust is analyzed to determine the coupling relationship between the magma flow and the regional stress field;

[0011] In combination with the fracture development condition, the driving effect of the magma flow on the fracture tectonic activity is analyzed based on the shear stress and normal stress distribution caused by the magma flow to determine the mutual relationship between the magma flow and the fracture structure.

[0012] Specifically, the establishment of the physical parameter model of each layer includes the following steps:

[0013] The stratigraphic structure is determined through geophysical exploration methods, and three macroscopic layers are divided in the deep area, including the crust layer, the plastic layer and the magma layer, to establish a layered model;

[0014] The density gradient model is used to describe the change of the density of each layer with depth, and the Young's modulus, shear modulus and compression modulus of each layer are determined;

[0015] The viscous shear force transmission mechanism between the magma layer and the plastic layer is analyzed, and the distribution of the shear stress and its influence on the deformation of the plastic layer are determined in combination with the laminar flow characteristics;

[0016] The friction force transmission mechanism between the plastic layer and the crust layer is analyzed, and the interlayer coupling effect is determined in combination with the driving force of the friction force on the horizontal movement of the crust layer and the stress accumulation effect.

[0017] Specifically, the method for establishing the magma laminar flow model includes:

[0018] According to the crust thickness, temperature and pressure data, a distribution model of the change of the magma density with depth is established to determine the size and direction of the density gradient;

[0019] Based on the spatial distribution of the density gradient, the flow area of the magma layer is divided to determine the velocity distribution characteristics of the magma in the thick and thin areas of the crust, including the flow deceleration behavior in the thickening area and the flow acceleration behavior in the thinning area;

[0020] Through comprehensive analysis of the flow direction, velocity distribution and density change, the shear stress generated by the magma flow on the plastic layer and its transmission effect in the plastic layer are calculated.

[0021] Specifically, the method for calculating the shear stress generated by the magma flow on the plastic layer includes:

[0022] The flow velocity V kIntralayer density variation and viscosity coefficient η k Calculate the viscous shear stress τ within the plastic layer. k =f(σ k V k η k ,...), σ k The horizontal stress of the plastic layer;

[0023] Based on the shear stress distribution model and combined with the physical properties of the plastic layer, including Young's modulus and shear modulus, a stress transfer model within the plastic layer is established.

[0024] Based on the magma flow characteristics in different crustal regions, we analyze the shear stress concentration zone within the plastic layer and its impact on crustal stress distribution.

[0025] By using a layered analysis method, the transmission effect of shear stress at different depths within the plastic layer is quantified, and its coupling effect on the crust is calculated.

[0026] Specifically, methods for determining the coupling relationship between magma flow and regional stress field include:

[0027] Obtain crustal thickness contour maps and delineate the areas of crustal thickness variation within the region, identifying thickening zones, thinning zones, and zones of abrupt thickness changes;

[0028] The velocity distribution characteristics of magma flow in different crustal thickness regions were analyzed, including the deceleration effect in thickening zones, the acceleration effect in thinning zones, and the flow direction deflection effect in zones of rapid thickness change.

[0029] The distribution of shear stress and normal stress induced by magma flow in different regions was calculated, and a regional stress field distribution model was established by combining the regional crustal thickness variation characteristics.

[0030] By comparing and analyzing the regional stress field distribution model and the magma flow model, the driving effect of magma flow on the stress field and its coupling relationship are determined.

[0031] Specifically, the direction of magma flow is related to the direction of the principal stress in the regional stress field, and the direction of the regional principal stress is the resultant direction of the secondary compressive stress induced by magma flow.

[0032] When the magma flow direction is stable, the direction of the principal stress is consistent with the direction of the earth displacement, and the included angle is acute; if the flow direction is unstable, the direction of the principal stress will deviate from the direction of the earth displacement.

[0033] Specifically, methods for determining the relationship between magma flow and fracture structures include:

[0034] The distribution of shear stress and normal stress in the fracture structure region caused by changes in flow direction and velocity is calculated based on the magma flow model.

[0035] In combination with the development conditions of the fracture, including the dip angle of the fracture surface, the shear strength and the stress concentration effect, the triggering effect of the shear stress and the normal stress on the fracture activity is analyzed;

[0036] For the area where the thickness of the crust changes, the shear stress concentration zone and the normal stress concentration zone are identified, and the high-risk area of the fracture tectonic activity is determined;

[0037] The dynamic coupling relationship between the magma flow and the fracture activity is analyzed, and the influence of the magma flow as a driving source on the fracture tectonic form is determined.

[0038] Specifically, the method for analyzing the dynamic coupling relationship between the magma flow and the fracture activity comprises the following steps of: determining the type of the surface rupture according to the shear stress concentration zone and the normal stress concentration zone, including compression fracture, strike-slip fracture and tension fracture;

[0039] In the crust thickening area, the magma flow causes the normal stress concentration in the area, and the compression stress increases; the distribution characteristics of the normal stress are analyzed, the stress concentration zone caused by the magma flow is identified, and the occurrence position and direction of the surface compression fracture are determined;

[0040] In the area where the direction of the magma flow is deflected, the shear stress increases; the driving effect of the shear stress on the horizontal dislocation of the fracture surface caused by the difference in the flow speed and the change in the direction of the magma flow is analyzed, and the activity area of the strike-slip fracture is determined;

[0041] In the crust thinning area, the flow speed of the magma flow increases, the normal stress decreases, and a tensile stress concentration zone is formed; the driving effect of the tensile stress on the tension activity of the fracture surface is analyzed, and the occurrence area and direction of the tension fracture are determined.

[0042] A computer readable storage medium stores a computer program, and the computer program is executed by a processor to realize the analysis method for the crust isopach-stress field-geological structure as described above.

[0043] A computer program product comprises a computer program / instruction, which is executed by a processor to realize the analysis method for the crust isopach-stress field-geological structure as described above.

[0044] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0045] The application determines the stratigraphic layer structure and establishes a physical parameter model by a geophysical exploration method, the stratigraphic layer structure includes a crust layer, a plastic layer and a magma layer; based on the change of the magma density gradient, a magma flow model is constructed to analyze the laminar flow characteristics and the flow velocity distribution in the area where the crust thickness changes; in combination with the regional crust thickness contour map, the stress field distribution of the magma flow in different crust thickness areas and the driving effect on the fault structure activity are analyzed, and the dynamic coupling relationship between the magma flow and the fault structure activity is obtained.

[0046] The application provides an accurate basis for analyzing the influence of magma flow on crust structure activity. The flow model established based on the change of the magma density gradient determines the flow characteristics and flow velocity distribution characteristics of the magma layer, especially the complex flow behavior in the area where the crust thickness changes. In combination with the regional crust thickness contour map, the stress field distribution is analyzed, the shear stress and normal stress are quantitatively analyzed, the accurate identification of the coupling relationship between the magma flow and the stress field is realized, and thus a scientific basis is provided for predicting the high-risk area of the fault structure activity.

[0047] In addition, the method of the application can also be used to analyze the correlation between the geological structure trace, the crust thickness contour and the stress field. By known conditions such as crust thickness, magma flow or stress distribution, other conditions can be deduced and analyzed, thereby providing a scientific basis for geological structure research, crust dynamic monitoring and stress field distribution prediction. BRIEF DESCRIPTION OF DRAWINGS

[0048] The accompanying drawings illustrate exemplary embodiments of the present application and together with the general description given above, and the detailed description given below, explain the principles of the application. In order to better facilitate the understanding of the present application, a brief description of the drawings is as follows:

[0049] Figure 1 Fig. 1 is a flowchart of an analysis method for crust isopach-stress field-geological structure according to the application.

[0050] Figure 2 Fig. 2 is an analysis model diagram of the crust surface rupture mechanism assumption according to the application.

[0051] Figure 3 Fig. 3 is a schematic diagram of the Mohr-Coulomb compression-shear failure mechanics model according to the application.

[0052] Figure 4 Fig. 4 is a schematic diagram of the magma flow model according to the application.

[0053] Figure 5 Fig. 5 is a schematic diagram of the ductile shear model according to the application.

[0054] Figure 6It is a crust thickness contour map of the western Sichuan block according to the present application.

[0055] Figure 7 It is a underground magma flow trend analysis map of the western Sichuan block according to the present application.

[0056] Figure 8 It is a analysis map of the relationship between magma flow and regional stress field according to the present application.

[0057] Figure 9 It is a analysis map of the relationship between magma flow and fracture activity according to the present application. DETAILED DESCRIPTION

[0058] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the related content, and not to limit the present application.

[0059] In addition, it should be further noted that, for the convenience of description, only the parts related to the present application are shown in the drawings.

[0060] The embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0061] The tectonic activity dynamic source and dynamic mechanism of the earth's crust are important research fields of earth science. The dynamic source usually refers to the starting mechanism and dynamic process of causing crustal activity, and the dynamic mechanism describes the occurrence mode of these processes and their influence on the tectonic activity of the crust. These researches are not only the key to understanding the crustal movement, but also provide a theoretical basis for predicting regional geological activities, which has important scientific and practical significance, such as in the fields of natural disaster assessment, construction site evaluation and mineral resources exploration.

[0062] At present, the plate tectonics theory as a widely recognized theoretical framework provides a basic framework for understanding the dynamic mechanism of crustal movement. Around this theory, relevant researches have made significant progress:

[0063] Theoretical research: in-depth study of the mantle convection, the internal thermodynamic process of the earth, the interaction between ocean and land, and the introduction of large system science and interdisciplinary research ideas, more information about the deep structure and internal process of the earth has been obtained, which further enriches the plate tectonics theory.

[0064] Theoretical verification: Through seismic wave propagation characteristics, gravity measurement of crust and mantle structure, geomagnetic measurement and other geophysical exploration technologies, the scale, speed and direction of crustal movement are obtained. In addition, using new technologies (such as synthetic aperture radar, satellite remote sensing) and numerical simulation means, the dynamic mechanism of mantle convection and plate interaction is intuitively understood and verified.

[0065] Plate dynamic mechanism research: The current mainstream view includes the thrust model (such as the seafloor spreading theory) and the pull model (such as the subduction plate drag hypothesis). In addition, the gravity slip self-driving model and the new continent drift theory proposed by Chinese scholars believe that the magma upwelling behind the continental plate is the main driving force of continental drift.

[0066] Although important progress has been made, due to the complexity of the deep structure of the earth and the limitations of exploration technology, the study of the dynamic source and mechanism of the crust still faces many challenges, such as the analysis of the deformation within the plate and the interaction between the plates.

[0067] In summary, since Wegener proposed the continental drift theory in 1912, the plate tectonics theory has gradually formed and been widely verified, but the dynamic source and mechanism of plate movement still have many unknown areas. Based on the improved crustal balance model, this invention attempts to explain and explore the geological structure activity in western Sichuan.

[0068] The crustal balance hypothesis is a theoretical model that explains the movement of the crust based on the plate tectonics theory, which believes that the crust is composed of multiple rock plates with different thicknesses and densities, and moves relative to the mantle's soft flow under the action of the earth's internal thermal convection, thus causing the redistribution of crustal material and topographic changes. This model can well explain geological phenomena such as plate drift, orogenic movement and earthquakes, but also has the following limitations:

[0069] Density difference assumption problem: The density difference setting in the hypothesis may be unreasonable.

[0070] Limitations of the mantle convection model: The current model is not accurate enough in describing the mantle convection.

[0071] Insufficient consideration of interlayer interaction: The material exchange and relative action between the crust and the mantle are ignored.

[0072] Simplification of dynamic mechanism: The dynamic mechanism of the plate boundary is simplified, and there is a lack of systematic analysis of the internal movement of the plate.

[0073] The invention divides the stratigraphic structure into three macroscopic layers: the crust layer, the plastic layer and the magma layer. The anti-deformation ability of each layer can be characterized by Young's modulus, shear modulus and compression modulus, and the material form and anti-deformation ability within these layers are gradually changing.

[0074] The present application considers that the plate movement of the crust layer is the result of deep magma movement (flow): compression shear deformation occurs during magma flow, and viscous force is generated between the magma layer and the plastic layer → leading to ductile shear deformation of the plastic layer, forming a ductile shear zone in the layer, and generating friction on the crust layer → the friction acts on the crust layer, driving the crust to move horizontally, but because the crust layer has increased resistance to deformation, shear stress is formed in the crust layer, and once it exceeds the shear strength, the layer is broken.

[0075] The following is the theoretical basis for the present application.

[0076] The present application analyzes the mechanical coupling effect between the layers and its influence on the tectonic activity of the crust by constructing a layered model of the crust layer, the plastic layer and the magma layer. Through the simplified model of the central plastic layer, the stress transmission mechanism and the rupture effect caused by magma flow are analyzed in depth.

[0077] Stratigraphic layering and stress analysis: in the plastic layer, magma flows at a speed V k Flow, generating viscous shear stress τ k = χ k (σ k , v k , η k ...), where η k represents the viscous coefficient in the layer. This shear stress is transmitted through the plastic layer to the crust layer, and is related to the horizontal stress σ1 in the crust layer. The value of σ1 in the crust layer can be represented as σ 1k = λ k (σ 1k , v 1k , η 1k ...).

[0078] When the crust thickness is uniform, as shown in Figure 2 (1), the viscous-friction force generated by magma between the layers is τ k1 = χ k1 (σ k1 , v k1 , η k1 ...). This force is closely related to the vertical self-weight normal stress σ 3k = σ 3k (y), where y is a function of depth. At this time, the crust layer can be regarded as a viscoelastic body, and the unit deformation thereof follows the Mohr-Coulomb strength criterion, as shown in Figure 3 .

[0079] When the crust thickness is thickened, as shown in Figure 2 (2), the magma flow speed V1 decreases. In the horizontal direction, the speed component V x produces a larger shear stress on the upper crust layer; in the vertical direction, the speed component Vx Increasing the value of the environmental normal stress σ1 makes it easier to induce stress concentration, thereby accelerating the formation of reverse thrust fracture.

[0080] When the thickness of the earth's crust decreases, such as Figure 2 As shown in (3), the magma flow velocity V1 increases. In the horizontal direction, the velocity component V... x The shear stress generated on the upper crust is more significant, which easily leads to the formation of normal faults; however, the vertical velocity component V x The reduction in stress decreases the value of the environmental normal stress σ1, thereby reducing the possibility of reverse thrust fracture.

[0081] Therefore, using crustal thickness as a reference, magma flow typically follows a pattern from thick to thin. However, its faulting pattern exhibits the following characteristics: thrust faults mainly occur in zones of abrupt change from thin to thick. Normal faults, on the other hand, are concentrated in the central regions of domes that transition from thick to thin, such as... Figure 4 As shown.

[0082] like Figure 5 As shown, the crustal layer, plastic layer, and magma layer are further divided into multiple micro-layers. The deformation modulus of each layer has a functional relationship with depth y, including the following expressions: Young's modulus: Shear modulus: Compression modulus: Deformation distance L of each layer k With vertical stress σ1, horizontal stress σ3, and viscous shear stress τ k+1 The relationship between modulus and modulus can be expressed as the following function:

[0083] When deep magma flows, it induces compression and shear deformation over a long distance. This deformation gradually propagates to the upper semi-liquid and semi-solid regions, forming ductile shear deformation. As the deformation propagates, the deformation range gradually decreases, while stress gradually concentrates. When the accumulated stress exceeds the shear strength of the crust, shear failure occurs.

[0084] From the cross-section, the entire deformation area exhibits a distinct triangular distribution. The deformation range and intensity are closely related to the following factors: stress state (σ1, σ3), rock mass (or magma) density, stratigraphic material state (liquid, semi-liquid / semi-solid, solid), and shear stress τ transmitted from the lower layer. k+1 Deformation modulus, burial depth

[0085] Deep magma movement is fluid and driven by changes in magma density gradient: deep within the Earth, magma exists in a fluid state with a certain density gradient. It is produced by melting under high pressure and tends to move towards a lower pressure state, thus generating flow.

[0086] The layers of the crust to the mantle are not two or three relatively homogeneous density bands, but should be a gradual change band with a certain density gradient under the gradually increasing surrounding rock pressure, and the temperature gradually increases. In theory, when the confining pressure is large enough, it exceeds the melting point of the material, the material will change into a liquid state, of course, at this time the liquid is very different from the molten liquid at high temperature and normal pressure, its density is larger than that of solid state, and its state is unstable, and it has a clear trend to develop to a state with lower density and smaller confining pressure, so it has a natural property to move to the dome position with thinner crust thickness, which is the main driving mechanism of magma flow and the internal driving mechanism of magma flow. This mechanism can form a theoretical closed loop with the inference in the previous text, which can also explain why geophysical exploration finds that the thickness of the crust is constantly changing.

[0087] Magma movement is driven by "flow potential": that is, when flowing from an area with large density (large confining pressure) to an area with small density (small confining pressure), the density will decrease and the speed will increase during the flow process due to the change of confining pressure, which is the main driving force; otherwise, the density will increase and the speed will decrease, which is the passive driving force; the flow performance is laminar flow. Therefore, the density gradient of the crust to the mantle is constantly present, but the density at the same depth is constantly changing, so the value of the density gradient is changing, and as long as the density gradient exists, the "flow potential" will exist, and the magma flow will occur spontaneously.

[0088] Embodiment one

[0089] As shown in Figure 1 , a method for analyzing crustal isopach-stress field-geological structure is provided, comprising:

[0090] The layered structure of the crust layer, plastic layer and magma layer is determined by geophysical exploration methods, and a physical parameter model of each layer is established; this model includes parameters such as Young's modulus, shear modulus and compression modulus, which are used to describe the deformation resistance and mechanical properties of each layer.

[0091] Based on the change of the magma density gradient, the flow behavior of deep magma in different crust thickness areas is analyzed, a magma laminar flow model is constructed, and the flow velocity distribution of the magma in the thickening area and the thinning area of the crust is calculated.

[0092] Combined with the regional crust thickness contour map, the influence of magma flow on the stress field distribution in different crust thickness areas is analyzed through the shear stress and normal stress distribution caused by magma flow, and the coupling relationship between magma flow and regional stress field is determined; the coupling relationship between magma flow and regional stress field is determined by studying the stress concentration phenomenon in the thickening area and the thinning area of the crust.

[0093] The driving effect of magma flow on fault tectonic activity is analyzed by using the shear stress and normal stress distribution caused by magma flow and combining the development conditions of the fault (such as the dip angle of the fault surface and the shear strength), the high-risk fault activity area is determined by quantifying the concentration area of the shear stress and the normal stress, and the relationship between the magma flow and the fault structure is determined.

[0094] Embodiment two

[0095] The physical parameter model of each layer is established by the following steps:

[0096] The stratigraphic structure is determined by geophysical exploration methods, and three macroscopic layers are divided in the deep region, including the crust layer, the plastic layer and the magma layer, and a layered model is established; the crust layer is a rigid geological structure of the surface layer. The plastic layer is between the crust and the magma layer and has strong toughness and plasticity. The magma layer is composed of high-temperature molten material and has fluidity.

[0097] The density gradient model is used to describe the change of the density of each layer with depth, and the Young's modulus, shear modulus and compression modulus of each layer are determined; the Young's modulus is the tensile deformation resistance of each layer. The shear modulus is the resistance of each layer to shear deformation. The compression modulus is the resistance of each layer to volume deformation. The density distribution of the crust to the mantle increases with depth, and the confining pressure causes the density of the material to gradually increase, but the density gradient changes with the different properties of the material. The deep temperature increases with depth, which may induce the transition of solid rock to liquid. Theoretical analysis shows that when the confining pressure exceeds the melting point pressure, the material will change into a high-density liquid, and the density gradient changes significantly.

[0098] The viscous shear force transmission mechanism between the magma layer and the plastic layer is analyzed, and the distribution of shear stress and its influence on the deformation of the plastic layer are determined combined with the laminar flow characteristics; the shear force is transmitted to the plastic layer layer by layer, which induces local ductile shear deformation and accumulates stress in the shear zone. The distribution of shear stress affects the deformation range and strength of the plastic layer.

[0099] The friction force transmission mechanism between the plastic layer and the crust layer is analyzed, and the interlayer coupling effect is determined combined with the driving force of the friction force on the horizontal movement of the crust layer and the stress accumulation effect. The friction force transmitted from the plastic layer to the crust layer forms the main driving force of the horizontal movement of the crust layer. Under the action of friction, the shear stress in the crust layer gradually accumulates. When the stress exceeds the shear strength of the crust layer, local rupture of the crust layer will be induced, which is manifested as fault activity or crust movement.

[0100] The method for establishing the magma layer flow model comprises:

[0101] According to the crust thickness, temperature and pressure data, a distribution model of the magma density with depth is established to determine the size and direction of the density gradient; the melting of the deep magma due to high pressure presents a non-uniform density distribution, and the gradient change is controlled by the confining pressure, temperature and magma composition. The local difference of the density gradient in the crust thick and thin change area directly affects the flow direction and speed. By establishing the distribution model, the trend of the flow from the area with larger density to the area with smaller density is determined, which is the basis of the driving mechanism of the flow potential.

[0102] Based on the spatial distribution of the density gradient, the flow area of the magma layer is divided, and the speed distribution characteristics of the magma in the crust thick and thin change area are determined, including the flow deceleration behavior in the thickening area and the flow acceleration behavior in the thinning area; in the crust thickening area, the magma flow speed decreases, showing flow resistance characteristics. In the crust thinning area, the magma flow speed significantly accelerates due to the decrease of the confining pressure. The flow direction tends to the area with smaller density gradient, showing accelerated flow. In the complex crust morphology, such as the dome or trough area, the magma flow shows local flow speed change and direction deflection.

[0103] Through the comprehensive analysis of the flow direction, speed distribution and density change, the shear stress generated by the magma flow on the plastic layer and its transmission effect in the plastic layer are calculated. The magma layer flow generates a ductile shear zone in the plastic layer, and the shear stress concentration area becomes the main path of stress transmission. The shear stress gradually transmits to the crust layer along the interlayer, affecting the deformation mode and failure mechanism of the crust. Especially in the crust thickening or thinning area, the transmission characteristics of the shear stress play a key role in the stress distribution of the crust. The size and variation law of the shear stress in different depths and areas are calculated by comprehensively considering the density gradient and flow speed field, and a stress distribution model is established.

[0104] The method for calculating the shear stress generated by the magma flow on the plastic layer comprises:

[0105] determining the flow speed V in the magma layer k , the density change and the viscosity coefficient η in the layer k , calculating the viscous shear stress τ in the plastic layer k =f(σ k , V k , η k ,...) σ k is the horizontal stress of the plastic layer; the flow speed of the magma layer changes with depth and is affected by the density gradient and pressure field. The density of the magma presents a non-uniform distribution due to the change of the confining pressure and temperature, showing gradient characteristics. The viscosity coefficient represents the rheological properties of the magma, and its value depends on the material composition and environmental conditions.

[0106] Based on the distribution model of shear stress, combined with the physical properties of plastic layer, including Young's modulus and shear modulus, the stress transfer model in the plastic layer is established; that is, the transfer law of shear stress in the layer and its influence on the deformation in the layer are described. The model can combine the density gradient and flow characteristics to determine the range and concentration area of shear stress.

[0107] According to the flow characteristics of the magma in the thick and thin areas of the crust, the shear stress concentration area in the plastic layer and its influence on the stress distribution of the crust are analyzed. In the thickening area, the shear stress concentration is more significant due to the decrease of flow velocity and the increase of normal stress, and the influence on the crust thickness is stronger. In the thinning area, the shear stress action range is expanded due to the accelerated flow, but the concentration degree is weaker.

[0108] Through the layered analysis method, the transfer effect of shear stress at different depths in the plastic layer is quantified, and the coupling effect on the crust layer is calculated. From the magma layer to the plastic layer, and then to the crust layer, the deformation range is reduced, but the stress is gradually concentrated. After the shear stress is transferred to the crust layer, the stress distribution of the crust layer is changed, which may trigger regional faulting.

[0109] As shown in Figure 6 and Figure 7 , the method for determining the coupling relationship between magma flow and regional stress field includes:

[0110] Obtain the crust thickness contour map, and divide the thick and thin areas of the crust in the region to determine the thickening area, such as some island-shaped or belt-shaped thickening zones, such as the Maoriba and the west of Malungo, with a thickness change range of several kilometers to more than ten kilometers. Thinning area, such as the trough belt and dome area of the western Sichuan block, with a thickness change range of several kilometers to more than ten kilometers. The sharply changing belt of thickness, such as the area where the "N" shaped resistance line is located, is an important area for the deflection of magma flow direction.

[0111] Analyze the flow velocity distribution characteristics of magma flow in different crust thickness areas, including the deceleration effect in the thickening area, the acceleration effect in the thinning area, and the flow direction deflection effect in the sharply changing belt of thickness; the deceleration effect in the thickening area: due to the increase of normal stress, the flow velocity of magma decreases. This effect is particularly significant in the thickening area from Daofu to Qianning, resulting in a slowdown of flow. The acceleration effect in the thinning area: the decrease of confining pressure leads to the acceleration of magma flow, which is common in the trough area from Wawushan to Leshan. The deflection effect in the sharply changing belt of thickness: in these areas, the direction of magma flow is deflected due to the change of stress field, such as the flow trend in the area from Daofu to Shimen.

[0112] The shear stress and normal stress distribution caused by magma flow in different areas is calculated, and a regional stress field distribution model is established in combination with the variation characteristics of regional crustal thickness. The normal stress: due to the compression effect of magma flow, the normal stress is concentrated in the thickening area, showing a higher crustal deformation ability. The stress calculation results show that the stress distribution is directly related to the characteristics of thick and thin areas, and is quantified through a regional specific model.

[0113] By comparing the regional stress field distribution model with the magma flow model, the driving effect of magma flow on the stress field and its coupling relationship are determined. By comparing the magma flow model and the regional stress field distribution model, the driving effect of magma flow on the stress field is determined:

[0114] The direction of magma flow is related to the direction of the principal stress of the regional stress field. The direction of the principal stress is the direction of the resultant force of the secondary compressive stress caused by magma flow.

[0115] If the direction of magma flow is stable, the direction of the principal stress is consistent with the direction of the earth's displacement, and the included angle is an acute angle. If the flow direction is unstable, the principal stress direction will be deflected from the direction of the earth's displacement.

[0116] The method for determining the relationship between magma flow and fault structure includes:

[0117] Based on the magma flow model, the distribution of shear stress and normal stress in the fault structure area caused by the change of flow direction and velocity is calculated. The change of magma flow velocity leads to shear stress concentration in the plastic layer and the fault zone. For example, in the crustal thinning area, the acceleration of flow increases the shear stress. In the crustal thickening area, due to the deceleration and compression effect of magma flow, the normal stress increases significantly, leading to intense deformation in the fault structure area.

[0118] In combination with the fault development conditions, including the fault surface dip angle, shear strength and stress concentration effect, the triggering effect of shear stress and normal stress on fault activity is analyzed. The fault surface dip angle is determined according to the fault dip angle in the thick and thin area of the crust, to judge the influence of stress distribution on the extension direction of the fault. The shear strength is used to evaluate the maximum shear stress that the fault surface can withstand, to infer its rupture possibility. The stress concentration effect is used to analyze how the shear stress concentration zone affects the intensity of fault activity, for example, the shear stress concentration in Jiulong area leads to the development of L-shaped faults.

[0119] For the thick and thin areas of the crust, the shear stress concentration zone and the normal stress concentration zone are identified, and the high-risk areas of fault structure activity are determined. The thrust faults in the thickening area, for example, the crust thickening area from Kangding to Jiulong, show a thrust fault concentration zone. The normal faults in the thinning area, for example, the crust thinning area from Wawushan to Leshan, are often normal faults

[0120] The dynamic coupling relationship between the magma flow and the fracture activity is analyzed to determine the influence of the magma flow as a driving source on the fracture tectonic pattern.

[0121] The method for analyzing the dynamic coupling relationship between the magma flow and the fracture activity comprises the following steps.

[0122] In the crust thickening area, the magma flow causes the stress concentration in the area, the compressive stress increases, the distribution characteristics of the normal stress are analyzed, the stress concentration zone caused by the magma flow is identified, and the occurrence position and direction of the surface compression fracture are determined.

[0123] In the area where the magma flow direction is deflected, the shear stress increases.

[0124] In the crust thinning area, the magma flow speed increases, the normal stress decreases, and a tensile stress concentration zone is formed.

[0125] Embodiment Three

[0126] As Figure 6 and Figure 7 , this embodiment provides a specific example.

[0127] According to the isograms of the crust thickness provided by Liu Yufa et al. Figure 6 The crust thickness is the largest in the west of Xinlong and is island-shaped, the depth is 70 km, and gradually thins to about 40 km in the southeast direction, and each place is uneven:

[0128] (1) The Mao Ribao in the west of Xiaojin and Maerkang, the northeast of Maerkang, and the area between Jiulong County and Shade Township appear three island-shaped bulges to the center of the earth, the belt-shaped thickening area appears in Ganluo, Jinyang and Dashanbao scenic area, the increase values are about 4 km, 3 km, 5 km and 12 km respectively, the long axis trends are about N22°W, N72°E, S41°E and SN respectively, and the lengths are about 70 km, 130 km, 50 km and 215 km respectively.

[0129] (2) From Xiaojin to the area of Baoxing and Mofanggou, from the northeast of Daocheng to Aden and Yalongjiang Town, from Mianning southward to Jinhe Township, from Xichang to Panzhihua, and from Wawushan to Leshan, Meishan, Qionglai, and Ya'an, there are 4 crustal thinning areas in the shape of an inverted trough and an inverted dustpan, with thinning thickness values of about 8 km, 2 km, 10 km, and 12 km respectively. The directions of the dustpan openings are S44°E, S55°E turning to S23°E, S7°W, and N47°E turning to N76°E respectively, and the ratios of their long / short axes are about 100 / 56 km, 150 / 52 km, ≥160 / 200 km, and ≥200 / 75 km respectively.

[0130] (3) There is a domed crustal thinning area from Yajiang to Zituoxi Township, Xinlong County, with a scale of about 99 km × 86 km and a thinning value of about 4 km.

[0131] (4) There is a faintly visible crustal thickening zone from Daofu to the northeast of Qianning (Huiyuan Temple), and the crust is thinning from Luding to Shimian and Mianning.

[0132] According to the method of the present invention, combined with Figure 6 the following results can be obtained as Figure 7 shown:

[0133] (1) The crustal thickness gradually thins from the northwest to the southeast. Therefore, the overall flow direction is consistent with this, and most are acceleration areas (shown by the dark arrows).

[0134] (2) There is a large-scale resistance line in the NW-SE direction of the region, with a width of about 50 - 150 km, forming a "乀"-shaped area with a reduced magma flow rate (shown by the light arrows): The location starts from the northwest of Maozhiba in the northwest of the region, passes through Daofu and Kangding, and extends to the line of Shimian, Yuexi, Jinyang, and Dashanbao. The reason is that there is an oval crustal thickening from Daofu to the northeast of Qianning, the rate of crustal thinning slows down and the gradient decreases from Luding to Shimian, Yuexi, and Mianning, and there is a dumbbell-shaped crustal thickening from Yuexi to Zhaojue and from Jinyang to Dashanbao.

[0135] (3) There are small areas with reduced flow rates locally: ① There is a resistance line formed by the island-shaped crustal thickening from Shade Township to Jiulong; ② In the areas of the trough valleys of the 4 inverted trough-shaped and inverted dustpan-shaped crustal thinning areas from Xiaojin to Baoxing and Mofanggou, from the northeast of Daocheng to Aden and Yalongjiang Town, and from Wawushan to Leshan, Meishan, Qionglai, and Ya'an, the rate of crustal thinning slows down and the gradient decreases, forming a resistance line.

[0136] (4) There are relatively stable areas locally: ① To the northwest of the line from Barkam to the northeast of Maozhiba, Kangding, Jiulong, Muli, and Yanyuan, the gradient change of the crustal thickness is small and the magma flow is relatively stable. To the southeast of this line, the gradient increases significantly and the magma flow rate increases significantly; ② The domed area of crustal thinning from Yajiang to Zituoxi Township, Xinlong County, is small in scale and small in thinning value, and is also a relatively stable area for magma activity. <00003

[0137] The relationship between magma flow and the regional stress field is determined as follows:

[0138] Depend on Figure 7 It can be seen that the direction of the regional stress field generally follows the same trend as the direction of GPS geodetic displacement, but there are significant differences in some areas. The difference between the direction of magma flow and the direction of GPS geodetic displacement is much smaller, and the overall pattern is as follows:

[0139] (1) In the northeast of Ma'erkang to Maoriba, and northwest of Kangding, Jiulong, Muli, and Yanyuan, where the crustal thickness gradient is small, the direction of the regional stress field shows a high degree of consistency with the direction of GPS geodetic displacement. Only in the northwest of the circular crustal thickening zone from Jiulong to Shade Township do their directions show a significant deviation (see...). Figure 8 of point).

[0140] (2) Although the crustal thickness varies greatly southeast of this line, within the range of uniform gradient change, the direction of the regional stress field shows a high degree of consistency with the direction of GPS geodetic displacement. The main differences fall into three subcategories: ① The range of stationary points of the second derivative of the crustal thickness gradient, i.e., the region with small changes during the process of drastic gradient change → small change → drastic change, such as... Figure 8 shown Points; ② In the crustal thinning zones of inverted troughs, inverted basins, and broad, gently domed areas, the regions with small gradient changes at their top and sides, such as... Figure 8 shown Point; ③ The back side of the island-like crustal thickening zone in the direction of magma flow, such as Figure 8 shown Point. Furthermore, if the magma flow direction within the region is stable, the angle between the principal stress direction and the geodetic displacement direction is acute and consistent with the overall flow direction, such as... Figure 8 shown Points, etc.; if the flow direction is unstable, the included angle is unstable, and the angle between the principal stress direction and the ground displacement direction is unstable, such as... Figure 8 shown Points, etc.

[0141] In summary, there is a close relationship between the direction of magma flow and the regional stress field and the direction of GPS geodetic displacement. It is preliminarily inferred that the direction of the regional principal stress is the resultant direction of the secondary compressive stress generated by the flow, and the direction of geodetic displacement is the resultant vector direction of the flow direction.

[0142] The relationship between magma flow and fracture structures is determined as follows:

[0143] Because of the crustal depth and shape, the rate and direction of magma movement have certain rules, which are reflected to the surface and cause the surface displacement and stress accumulation to present good regularity, and further cause the surface rupture to have good regularity.

[0144] (1) Mao Ribab and north of Luhuo to Daofu and south of Kangding exist a blocking zone, and because of the existence of the invisible island-shaped thickening area in front of the flow, it is easy to accumulate higher stress, which is reflected to the surface and presents compression and strike-slip characteristics, and mainly strike-slip, the mechanical mode is compression and shear.

[0145] (2) The entire area from Baoxing, Lushan to Maoxian is in a reduced resistance zone, but because of the crustal thickness gradient change and the convergence trend to Chengdu area, and Chengdu is a large dome area, which is an invisible blocking area, plus the small gold slot-shaped crustal thinning area leading to the accelerated flow of the two sides, therefore, the region presents obvious compression, and the strike-slip feature is not obvious, which is conducive to the accumulation of high stress, and the surface rupture has obvious thrust characteristics; from west of Baoxing to Dachuan town, it is slightly in a state of extension due to the intersection of magma flow trend, the mechanical mode is tension, but it is not conducive to stress accumulation, from Dachuan town to Dujiangyan, it is slightly compressed, but the stress accumulation is limited, the section with high stress accumulation and rapid development is located in the northeast of Dujiangyan.

[0146] (3) The south of Mianning and Xichang presents obvious tension and left-lateral strike-slip characteristics, the mechanical mode is shear, and the stress accumulation is limited.

[0147] (4) The area around Muli has strong compression characteristics, Muli to the west of Mianning and Muli to the south of Dangcheng present shear strike-slip characteristics, the mechanical mode is compression and compression and shear, which are conducive to the accumulation of higher stress; Litang to Muli is located at the edge of the Yajiang dome and Jiulong island-shaped thickening area, which has little effect on stress accumulation, and the surface rupture presents left-lateral strike-slip characteristics.

[0148] (5) Because of the existence of Jiulong island-shaped thickening area, the northwest flow rate decreases and the southeast flow rate increases, there is a obvious compression area in Shadai that can accumulate higher stress, and the surface rupture is thrust; there is a obvious tension stress accumulation area in Jiulong county and northwest, combined with the effect of Yajiang dome and Kangding invisible blocking area, it can accumulate higher stress in the west of Kangding, the mechanical mode is mainly compression and shear, the surface rupture presents the characteristics of mainly strike-slip and thrust, and the area around Jiulong county is mainly tension, which is represented by normal fault, and the two are connected to form a peculiar "L" shaped fracture developed at the same time; similar mechanisms also exist in the fracture structures of Muli-Yanshuan and Baoxing areas.

[0149] (6) The central part of the Y-shaped structure in western Sichuan (from Luding to Shimian) shows shear-compression features, which is the boundary between the northern strike-slip compression fault and the southern strike-slip fault.

[0150] In summary, the magma flow is closely related to the regional fault tectonic activity, and is the power source of the fault tectonic activity. The surface rupture characteristics and rupture mechanism of the fault can be explained by the geomechanical mechanism.

[0151] Embodiment Four

[0152] A computer readable storage medium stores a computer program, and the computer program is executed by a processor to implement the analysis method for crustal isopach-stress field-geological structure as described above.

[0153] Without loss of generality, the computer readable medium can include computer storage media and communication media. The computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information such as computer readable instructions data structures, program modules or other data. The computer storage medium includes RAM, ROM, EPROM, EEPROM, flash memory or other solid state storage technology, CD-ROM, DVD or other optical storage, magnetic cassette, magnetic tape, disk storage or other magnetic storage device. Of course, those skilled in the art can know that the computer storage medium is not limited to the above several. The system memory and mass storage device described above can be collectively referred to as memory.

[0154] A computer program product includes computer programs / instructions, which are executed by a processor to implement the analysis method for crustal isopach-stress field-geological structure as described above.

[0155] The computer program product includes computer programs or instruction sets for performing specific tasks or implementing specific functions. These programs or instructions are designed to be executed by the processor, so as to implement a series of predefined steps or operations. The program product can be stored in various forms of computer storage medium, such as memory, hard disk, solid state drive, optical disk or other forms of digital storage device. It can exist in the form of compiled binary code, or in the form of script or bytecode executable by interpreter. The program product is designed by careful algorithm and logic instruction, so that the processor can process data in a specific order and way, complete various functions such as data analysis, user interaction, device control, etc.

[0156] In the description of the specification, the description of the terms "one embodiment / way", "some embodiments / ways", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment / way or example are included in at least one embodiment / way or example of the present application. In the description of the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment / way or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments / ways or examples. In addition, the person skilled in the art can combine and combine the different embodiments / ways or examples described in the specification and the features of the different embodiments / ways or examples, without contradiction.

[0157] In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0158] The person skilled in the art should understand that the above-mentioned embodiments are only for clearly illustrating the present application, and are not intended to limit the scope of the present application. Other changes or modifications can be made on the basis of the above-mentioned application, and these changes or modifications are still within the scope of the present application.

Claims

1. A method for the analysis of crustal isopach-stress field-geologic structure, characterized by, The method comprises the following steps: determining the stratigraphic structure through geophysical exploration methods, and dividing three macroscopic layers in the deep region, including the crust layer, the plastic layer and the magma layer, to establish a layered model; determining the density gradient model to describe the change of the density of each layer with depth, and determining the Young's modulus, shear modulus and compression modulus of each layer; analyzing the viscous shear force transmission mechanism between the magma layer and the plastic layer, combining the laminar flow characteristics, to determine the distribution of shear stress and its influence on the deformation of the plastic layer; analyzing the friction force transmission mechanism between the plastic layer and the crust layer, combining the driving force of the horizontal movement of the crust layer and the stress accumulation effect of the friction force, to determine the interlayer coupling effect. The method for establishing the magma flow model comprises: establishing a distribution model of the density of the magma with depth according to the crust thickness, temperature and pressure data, to determine the size and direction of the density gradient; based on the spatial distribution of the density gradient, dividing the flow region of the magma layer, and determining the velocity distribution characteristics of the magma in the thick and thin change regions of the crust, including the flow deceleration behavior in the thickening region and the flow acceleration behavior in the thinning region; comprehensively analyzing the flow direction, velocity distribution and density change, to calculate the shear stress generated by the magma flow on the plastic layer and its transmission effect in the plastic layer. The method for calculating the shear stress generated by the magma flow on the plastic layer comprises:

2. The method for crustal isopach-stress field-geologic structure analysis according to claim 1, characterized in that, based on the distribution model of the shear stress, combining the physical properties of the plastic layer, including the Young's modulus and the shear modulus, to establish a stress transmission model in the plastic layer; according to the magma flow characteristics in the thick and thin regions of the crust, analyzing the shear stress concentration area in the plastic layer and its influence on the crust stress distribution; through the layered analysis method, quantifying the transmission effect of the shear stress at different depths in the plastic layer, and calculating the coupling effect on the crust layer. The method for determining the coupling relationship between the magma flow and the regional stress field comprises:

3. The method according to claim 2, wherein, obtaining the crust thickness contour map, and dividing the thick and thin change regions of the crust in the region, to determine the thickening region, the thinning region and the thick and thin sharp change belt; Determining flow velocity within a magma layer , density variation and viscosity coefficient within the layer , calculating viscous shear stress within a plastic layer , horizontal stress for a plastic layer; analyzing the flow velocity distribution characteristics of the magma flow in different crust thickness regions, including the deceleration effect in the thickening region, the acceleration effect in the thinning region, and the flow direction deflection effect in the thick and thin sharp change belt; calculating the shear stress and normal stress distribution induced by the magma flow in different regions, combining the crust thickness change characteristics, to establish a regional stress field distribution model; through the comparative analysis of the regional stress field distribution model and the magma flow model, determining the driving effect of the magma flow on the stress field and the coupling relationship.

4. The method for crustal isopach-stress field-geologic structure analysis according to claim 1, characterized in that, ​ ​ ​ ​ ​ 5. The method for crustal isopach-stress field-geologic structure analysis according to claim 4, characterized in that, The magma flow direction is related to the principal stress direction of the regional stress field, and the principal stress direction is the resultant force direction of the secondary compressive stress induced by the magma flow; If the magma flow direction is stable, the principal stress direction is consistent with the direction of the earth displacement, and the included angle is an acute angle; if the flow direction is unstable, the principal stress direction will be deflected from the direction of the earth displacement.

6. The method for crustal isopach-stress field-geologic structure analysis according to claim 1, characterized in that, The method for determining the relationship between the magma flow and the fault structure comprises: calculating the distribution of the shear stress and the normal stress in the fault structure region induced by the change of the flow direction and the speed of the magma flow based on the magma flow model; combining the fault development conditions, including the fault surface dip angle, the shear strength and the stress concentration effect, analyzing the triggering effect of the shear stress and the normal stress on the fault activity; for the region with the change of the crust thickness, identifying the shear stress concentration zone and the normal stress concentration zone, and determining the high-risk region of the fault structure activity; analyzing the dynamic coupling relationship between the magma flow and the fault activity, and determining the influence of the magma flow as the driving source on the fault structure shape.

7. The method for crustal isopach-stress field-geologic structure analysis according to claim 6, characterized in that, The method for analyzing the dynamic coupling relationship between the magma flow and the fault activity comprises: determining the type of the surface rupture, including the compression fracture, the strike-slip fracture and the tension fracture, according to the shear stress concentration zone and the normal stress concentration zone; wherein, in the crust thickening region, the magma flow induces the normal stress concentration in the region, and the compression stress increases; analyzing the distribution characteristics of the normal stress, identifying the stress concentration zone caused by the magma flow, and determining the occurrence position and direction of the surface compression fracture; in the region where the magma flow direction is deflected, the shear stress increases; combining the shear stress, analyzing the driving effect of the speed difference and the direction change of the magma flow on the horizontal dislocation of the fault surface, and determining the activity region of the strike-slip fracture; in the crust thinning region, the magma flow speed increases, the normal stress decreases, and the tensile stress concentration zone is formed; analyzing the driving effect of the tensile stress on the tension activity of the fault surface, and determining the occurrence region and direction of the tension fracture.

8. A computer-readable storage medium storing a computer program, the computer program comprising instructions that, when executed by a computer, cause the computer to perform the method of any one of claims 1 to 7. The computer program is executed by the processor to realize the analysis method for the crust isopach-stress field-geological structure according to any one of claims 1-7.

9. A computer program product comprising computer programs / instructions, characterized in that, The computer program / instruction is executed by the processor to realize the analysis method for the crust isopach-stress field-geological structure according to any one of claims 1-7.

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