Simulation device and method for interaction of underground mantle column, retention plate sheet and plate sheet hole

Abstract

The invention provides a device and a method for simulating interaction of a mantle column, a retention plate sheet and a plate sheet hole, and belongs to the field of plate structure and geodynamics. According to a similarity criterion, the density relation and the viscosity relation of the upper / lower mantle, the mantle columns and the retention plate sheets are reasonably set through a specific simulation material system; a high-density POM (Polyoxymethylene) plastic ring is added into a retention plate sheet material, so that plate sheet holes in the retention plate sheet are prevented from deforming; the flow-in speed of the mantle column is adjusted through the lifting platform; the simulation device highly restores the kinematics and deformation process of interaction of the mantle column, the retention plate sheet and the plate sheet hole in the nature; and in combination with an experiment process observation system, key construction events generated in the experiment process can be observed. According to the simulation device and method provided by the invention, a physical simulation experiment of interaction of the underground mantle column, the retention plate and the plate hole can be conveniently carried out, and technical support is provided for researches on underground mantle column branches, retention plate deformation, in-plate hot spot action and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of plate tectonics and geodynamics, and particularly relates to a simulation device and method for interaction of mantle plume-stagnant slab-slab hole. BACKGROUND

[0002] The mantle is the main part of the solid earth (volume ratio of about 80%, mass ratio of about 70%), and there is active thermal / material convection activity in the mantle. In the process of mantle convection, the mantle plume is a typical way of upwelling of hot and light lower mantle material, which is manifested as a large range of low-velocity body in the deep part of the earth and as a sea mountain chain and large igneous province on the earth's surface. Therefore, the mantle plume hypothesis is an important supplement to the plate tectonics theory and an important part of the geodynamics theory. In recent years, topographic and gravity observations of Venus, Mars and other terrestrial planets also show that the mantle plume may also play an important role in the geological evolution of other terrestrial planets.

[0003] After the oceanic plate is subducted into the mantle, it often lies flat on the interface between the upper / lower mantle (660 km discontinuity) and becomes a stagnant slab, which is particularly common in the western Pacific Ocean, especially in Southeast Asia. During the subduction of the oceanic plate, the subducted slab may appear partial disconnection, tearing and partial melting to form a local defect, which is called a slab hole. When the upwelling mantle plume located in the lower mantle encounters the stagnant slab or the slab hole at 660 km, it is still unclear what geological phenomena will occur.

[0004] Deep observation methods such as seismic tomography can only obtain the present-day, low-resolution (hundred-kilometer level) mantle deep structure, and cannot obtain the mantle evolution process on the order of millions of years, nor can they observe the fine structure of the mantle plume tail (diameter of several tens of kilometers) of small size. Therefore, it is necessary to study the interaction of mantle plume-stagnant slab-slab hole through geodynamic simulation means.

[0005] Many physical simulation experiments on mantle plumes have been carried out by predecessors, and a series of contributions have been made in terms of simulation materials (syrup, glycerol, silicon oil, etc.) and generation methods (thermal drive, buoyancy drive, etc.) of the mantle plume. However, predecessors have not carried out physical simulation experiments on the interaction of mantle plume and stagnant slab, nor have they carried out physical simulation experiments on the interaction of mantle plume and slab hole, and the experimental materials and experimental methods involved in the related experiments lack guidance from public literature.

[0006] The difficulties in carrying out the experiment of the interaction between the mantle plume and the stagnant slab are as follows: (1) in order to make the stagnant slab suspend at the interface (660 km discontinuity) between the upper mantle and the lower mantle, the density of the stagnant slab needs to be between the upper mantle and the lower mantle; the density difference of the commonly used simulation materials (glucose syrup with different concentrations) of the upper and lower mantles is usually very small, so the simulation material of the stagnant slab with a specific density must be accurately prepared; (2) the specific experimental method for making the stagnant slab uniformly settle at the 660 km discontinuity is not clear.

[0007] The difficulties in carrying out the experiment of the interaction between the mantle plume and the slab hole are as follows: (1) if a hole is opened in the stagnant slab to simulate the slab hole, the size of the stagnant slab and the slab hole will gradually decrease in the experiment; this is because the stagnant slab is usually simulated by a viscous material (such as silica gel), which will gradually deform under the action of confining pressure when placed in the mantle fluid material (such as glucose syrup) for a long time; (2) if a rigid material (such as an acrylic plate) is used to simulate the stagnant slab and a hole is punched in the rigid material to simulate the slab hole, the size of the stagnant slab and the slab hole will not decrease in the experiment, but this simulation method will lead to a new problem that the deformation process of the stagnant slab when interacting with the mantle plume cannot be observed. SUMMARY

[0008] In order to solve the above research needs and experimental difficulties, the purpose of the present application is to provide a simulation device and method for the interaction between the mantle plume, the stagnant slab and the slab hole, so as to restore the system of the interaction between the mantle plume, the stagnant slab and the slab hole in nature, and facilitate the physical simulation experiment of the interaction between the mantle plume, the stagnant slab and the slab hole.

[0009] The simulation device for the interaction between the mantle plume, the stagnant slab and the slab hole provided by the present application comprises a main experimental device and a stagnant slab. The main experimental device comprises an experimental cylinder, a geological model in the experimental cylinder, a mantle plume simulation device, a lifting platform and an electronic scale. The geological model in the experimental cylinder comprises an upper mantle and a lower mantle, which are arranged in a layered form in the experimental cylinder; the mantle plume simulation device comprises a container and a mantle plume simulation material arranged in the container; the upper mantle, the lower mantle and the mantle plume simulation material are made of glucose syrup with different concentrations; the side surface of the mantle plume container is connected with a plastic conduit through a second through-plate joint, and the other end of the plastic conduit is connected with the bottom of the experimental cylinder through a first through-plate joint. The lifting platform is used to adjust the height of the container to control the pressure head of the mantle plume simulation material; the lifting platform is placed on the electronic scale, and the electronic scale is used to monitor the mass change in the container in real time, so as to quantitatively calculate the inflow rate of the mantle plume simulation material. The retentive plate piece is arranged in the upper mantle, and a plurality of round holes are arranged on the retentive plate piece, and POM plastic rings are arranged in the round holes to simulate plate holes; the retentive plate piece is subjected to negative buoyancy in the upper mantle.

[0010] Preferably, the viscosities of the mantle column simulation material, the upper mantle, the lower mantle and the retentive plate piece are sequentially increased, and the plate hole is a rigid body; the densities of the mantle column simulation material, the upper mantle, the retentive plate piece and the plate hole, and the lower mantle are sequentially increased.

[0011] The application further provides a simulation method of a simulation device based on the interaction of a mantle column-retentive plate piece-plate hole, which comprises the following steps: Step S1: determining the material and size parameters of each component in the simulation device according to the geometric size, rheological strength and density or buoyancy parameters of a geological prototype in nature to be simulated, and manufacturing the simulation device; Step S2: assembling the simulation device, and taking the middle part of the upper surface of the upper mantle as the initial position of the retentive plate piece after the simulation device is stable, and taking the interface between the upper mantle and the lower mantle as the simulation of the 660 km discontinuous surface, and taking the middle part of the 660 km discontinuous surface as the preset sinking position of the retentive plate piece; arranging high-definition cameras at different shooting angles around the simulation device to form an experimental process observation system, and starting a timing photographing function to record the subsequent experimental process; Step S3: placing the retentive plate piece containing the plate hole at the initial position in the initial stage of the experiment; the retentive plate piece starts to sink in the upper mantle and gradually sinks to the preset sinking position; Step S4: adjusting the height of the lifting table to make the pressure head of the mantle column simulation material in the container higher than the total pressure head of the upper and lower mantles in the experimental cylinder, starting to supply the mantle column simulation material to the bottom of the experimental cylinder through the first plate penetrating joint and generating a mantle column, and recording the mass change of the mantle column simulation material through the electronic scale and calculating the volume change; Step S5: observing and recording the deformation characteristics and occurrence time of key tectonic events; Step S6: reducing the height of the lifting table, stopping the supply of the mantle column simulation material to the bottom of the experimental cylinder, and simulating the extinction process of the mantle column in nature; Step S7: observing and recording the subsequent deformation characteristics and occurrence time. The application has the following beneficial effects: (1) This invention provides a simulated material system comprising the upper mantle, lower mantle, mantle plume, stagnant plate, and plate cavity, which can simulate the upwelling and deformation process of mantle plume, the deformation of stagnant plate caused by mantle plume upwelling, the accumulation and lateral diffusion of lower mantle plume caused by stagnant plate, the upwelling morphology of mantle plume after passing through plate cavity, and the mantle flow in the upper and lower mantle caused by mantle upwelling, etc. Since the density, viscosity, and geometric dimensions of the simulated material system are similar to those of natural systems, the experimental simulation results can be approximated to the long-term ductile deformation of macroscopic geological bodies at the mantle scale in nature.

[0012] (2) This invention also provides a simulation device and method for simulating the interaction between mantle plumes and stagnant plates / plate cavities. This method can simulate plate cavities of different shapes / sizes / locations, stagnant plates that have subsided to the upper / lower mantle boundary at 660 km, the generation and demise of mantle plumes, and the control of mantle plume upwelling flux. With the help of the device of this invention, researchers can conduct in-depth investigations into the geological changes and impacts caused by the mantle plume upwelling process, and provide a powerful tool for understanding its geodynamic mechanism. Attached Figure Description

[0013] Figure 1 A schematic cross-sectional view of the main experimental apparatus of the simulation device for the interaction between mantle plume, stagnant plate, and plate cavity provided by the present invention; Figure 2 This is a planar schematic diagram of the retention plate simulation body provided by the present invention; Figure 3 This is a three-dimensional schematic diagram of the experimental cylinder base platform provided by the present invention; Figure 4 A side view of the evolution of experimental simulation results provided for an embodiment of the present invention. Figure 5 An evolution diagram (bottom view) of the experimental simulation results provided for an embodiment of the present invention.

[0014] Among them, 1-initial position of the retention plate, 2-preset settlement position of the retention plate, 3-upper mantle, 4-lower mantle, 5-experimental cylinder, 6-slider, 7-first through-plate joint, 8-plastic conduit, 9-second through-plate joint, 10-mantle plume simulation material, 11-lifting platform, 12-electronic scale, 13-plate hole, 14-retention plate, 15-stainless steel bracket, 16-fumarole. Detailed Implementation

[0015] To provide a clearer understanding of the technical features, objectives, and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail with reference to the following specific embodiments, but this should not be construed as limiting the scope of implementation of the present invention.

[0016] This embodiment provides a simulation device and method for the interaction between mantle plumes, retained slabs, and slab cavities. Based on the geometric characteristics, density relationships, rheological strength, and similarity principles of natural geological prototypes, the density or buoyancy relationships and viscosity relationships of the upper / lower mantle, mantle plumes, and retained slabs are rationally set. High-density POM plastic rings are introduced into the retained slab material to simulate slab cavities and prevent deformation. The generation or cessation of the mantle plume is adjusted via a lifting platform. Key tectonic deformation events during the experiment are observed through an experimental process observation system. This simulation device highly replicates the natural environment and, combined with the experimental process observation system, allows for the observation of key tectonic events generated during the experiment. The simulation device and method provided by this invention facilitate physical simulation experiments of the interaction between mantle plumes, retained slabs, and slab cavities, providing technical support for research on mantle plume branching, retained slab deformation, and intraplate hotspot effects.

[0017] This embodiment provides a simulation device structure for mantle plume-retained plate-plate cavity interaction, as follows: Figures 1-3 As shown, it includes the main experimental apparatus, the retention plate 14, and the experimental cylinder base platform.

[0018] Figure 1 The cross-sectional structure of the main experimental apparatus includes an experimental cylinder 5, an upper mantle 3, a lower mantle 4, a first through-plate joint 7, a plastic conduit 8, a second through-plate joint 9, a mantle column simulation device, a lifting platform 11, and an electronic scale 12.

[0019] Experimental tank 5 is made of acrylic. The simulated materials for upper mantle 3 and lower mantle 4 are arranged in two layers within the tank, with the interface representing a simulated 660km discontinuity. The simulated material for upper mantle 3 is made of 80wt% light yellow glucose syrup with a density of approximately 1410 kg·m³. -3 The lower mantle 4 simulation material was simulated using 84 wt% dark yellow glucose syrup with a density of approximately 1440 kg·m³. -3 The mantle plume simulation device includes a container and mantle plume simulation material 10 placed inside the container. The mantle plume simulation material 10 is a glucose syrup dyed red with 78 wt% water-based dye and has a density of approximately 1395 kg·m³. -3 That is, the density relationship of the three materials satisfies the condition that mantle plume simulation material 10 < upper mantle 3 simulation material < lower mantle 4 simulation material, and the viscosity relationship of the three materials also needs to satisfy the condition that mantle plume simulation material 10 < upper mantle 3 simulation material < lower mantle 4 simulation material. This is a proportional adjustment based on the relationship of the geological prototype in nature, which can ensure that the upper and lower mantles will not be mixed after long-term storage. At the same time, the mantle plume generated by mantle plume simulation material 10 in experimental tank 5 can float stably in both the upper and lower mantles by its own buoyancy.

[0020] The bottom of the experimental cylinder 5 is provided with a first through-plate connector 7, and the lower side of the container is provided with a second through-plate connector 9. The plastic conduit 8 connects the first through-plate connector 7 and the second through-plate connector 9 and is used to supply the mantle plume simulation material 10 to the experimental cylinder 5.

[0021] The lifting platform 11 is connected to the container. By adjusting the height of the lifting platform 11, the height of the container can be controlled to control the pressure head of the mantle plume simulation material 10, thereby controlling the inflow rate of the mantle plume simulation material 10 at the bottom of the experimental cylinder 5. The lifting platform 11 is placed on an electronic scale 12, which monitors the mass change inside the mantle plume container in real time, and then quantitatively calculates the mass flow rate and volumetric flow rate of the mantle plume simulation material 10. When the pressure head of the mantle plume simulation material is equal to the total pressure head of the upper and lower mantle in the experimental cylinder, the mantle plume simulation material stops flowing into the experimental cylinder.

[0022] Figure 2 The structure of the retention plate 14 is shown. The retention plate 14 is placed in the upper mantle 3 and is made of a homogeneous mixture of iron powder and silica gel with a density of approximately 1425 kg·m³. -3 The retention plate 14 is equipped with two plates with a density of 1415 kg·m³. -3 The POM plastic ring simulates the plate cavity 13, and the density of plate cavity 13 is approximately 1415 kg·m³. -3 The density is similar to that of the stagnant plate 14, and the density is between that of the upper mantle 3 simulated material and the lower mantle 4 simulated material. This precise density setting can ensure that when the stagnant plate 14 with the plate hole is placed into the experimental tank after the experiment starts, the stagnant plate 14 with the plate hole can be suspended on the 660 km discontinuity under human operation.

[0023] Figure 3 The experimental cylinder base platform includes an "h"-shaped acrylic slider 6, a stainless steel bracket 15, and casters 16. The stainless steel bracket 15 is a hollow frame used to support the acrylic experimental cylinder 5, leaving a distance between the experimental cylinder and the ground to facilitate the connection of the plastic conduit to the bottom of the acrylic experimental cylinder. The upper four crossbeams of the stainless steel bracket 15 are equipped with several acrylic sliders 6 to support and fix the acrylic experimental cylinder above. The lower part of the stainless steel bracket 15 is fixed with four casters to facilitate the movement, fixation, and height adjustment of the experimental device.

[0024] This invention also provides a simulation method for simulating the interaction between a mantle plume, a retained plate, and a plate cavity, applied to the aforementioned experimental simulation apparatus and materials. The method specifically includes the following steps: Step S1: Investigate the geometry, rheological strength, and density or buoyancy parameters of the natural geological prototype to design the material and dimensional parameters of each component in the simulation device. Before determining the parameters of the scaled experimental model, investigate the geometric, rheological strength, and density or buoyancy parameters of the natural geological prototype.

[0025] Retained slabs in nature are typically old oceanic lithosphere, with a thickness generally less than 100 km (the limit of oceanic lithosphere thickening due to cooling). The viscosity ratio (strength ratio) between the oceanic lithosphere and the upper mantle usually differs by 2-4 orders of magnitude, and the density difference (negative buoyancy) can reach up to 40 kg m³. -3 (Normal basaltic oceanic crust) or 80 kg m -3 (Oceanic crust fully eclogized). Retained slabs in nature often develop slab cavities. For example, in the present-day Southeast Asia, 660 km away, most slab cavities have diameters between 100 and 1000 km.

[0026] In nature, the upper and lower mantle are separated by a 660 km discontinuity. The viscosity ratio (strength ratio) of the upper and lower mantle usually differs by 1-2 orders of magnitude.

[0027] Natural mantle plumes form at the base (approximately 2900 km depth) or interior (approximately 2900–660 km depth) of the lower mantle and rise due to thermal buoyancy or compositional buoyancy. If the mantle plume is 300 K warmer than the surrounding mantle (maximum temperature difference), it can cause an upwelling of approximately 40–45 kg m³. -3 The density difference (the maximum positive buoyancy of the mantle plume upwelling). The tail diameter of a mantle plume is generally less than 1000 km, and the maximum diffusion diameter after the mantle plume reaches the bottom of the lithosphere can reach 2000-2500 km.

[0028] Given the geometric, rheological strength, and density or buoyancy parameters of the natural geological prototype, the following experimental model parameters were designed based on the criteria of geometric similarity, kinematic similarity, dynamic similarity, and rheological similarity: The design dimensions of the retention plate 14 are 25cm × 25cm × 1cm, and the density is 1425 kg·m³. -3 The viscosity is 24000 Pa·s; The number of holes 13 in the plate is 2, with inner diameters of 2 cm and 3 cm, outer diameters of 3 cm and 4 cm, and a distance of 10 cm between them; The mantle plume was designed with a diameter of 0.8 cm and a density of... 1395 kg·m -3 The viscosity is 10 Pa·s; Design thickness of upper mantle 3 It is 6.6 cm and has a density of 1410 kg·m -3 The viscosity is 30 Pa·s; Design thickness of lower mantle 4 10 cm, density 1440 kg·m -3 The viscosity is 300 Pa·s.

[0029] Note that the lower mantle 4 here does not simulate the full thickness of the lower mantle in nature (2300 km), but only simulates the local thickness of the lower mantle (1000 km) in nature, considering the limitations of the overall size of the model. Since mantle plumes may be generated inside the lower mantle in nature, this design is reasonable.

[0030] In the experimental model, 1 cm corresponds to 100 km in nature. That is, the prototype thickness of the residing plate 14 is 100 km, the prototype diameters of the two plate holes 13 are 200 km and 300 km respectively, the distance between the two prototype plate holes 13 is 1000 km, the prototype thickness of the upper mantle 3 is 660 km, and the prototype (partial) thickness of the lower mantle 4 is 1000 km. All of the above geometric dimensions are within a reasonable range.

[0031] In the simulation device, the density of the simulated material in the upper mantle 3 is lower than that in the simulated material in the lower mantle 4, ensuring that the two will not mix after long-term stabilization. The negative buoyancy of the simulated material in the upper mantle 3 is -15 kg·m. -3 This ensures that the retention plate 14 can sustainably settle within the upper mantle 3; and the density of the retention plate 14 is between that of the upper and lower mantle, ensuring that the retention plate 14 can remain on the 660 km discontinuity. The density of the mantle plume simulation material 10 is less than that of the upper mantle 3 simulation material, ensuring that the mantle plume simulation material 10 can stably float in both the upper and lower mantle. The positive buoyancy of the mantle plume simulation material 10 in the lower mantle 4 simulation material and the upper mantle 3 simulation material is +45 kg·m. -3 +15 kg·m -3 The density / buoyancy designs described above are all within the reasonable range found in nature.

[0032] In the experimental model, the viscosity of the stagnant plate 14 is two orders of magnitude (800 times) higher than that of the upper mantle 3, and the viscosity of the lower mantle 4 is one order of magnitude (10 times) higher than that of the upper mantle 3. The viscosity of the mantle plume simulation material 10 is lower than that of the upper mantle 3 and the lower mantle 4. All of the above rheological strength designs are within the reasonable range in nature.

[0033] After designing the parameters of each component of the simulation device, the necessary simulation materials are prepared, specifically including: Step S1.1: Mantle plume simulation material 10 and upper and lower mantle simulation materials are made using glucose syrup of different concentrations. The upper mantle 3 simulation material uses glucose syrup with a concentration of 80wt%, the lower mantle 4 simulation material uses glucose syrup with a concentration of 84wt%, and the mantle plume simulation material 10 uses glucose syrup with a concentration of 78wt% dyed with a small amount (a few milliliters) of red water-based fuel to facilitate observation of its flow in the upper and lower mantle. Step S1.2: Use 600,000 molecular weight silica gel (density 970 kg·m³). -3 ) and 80-mesh iron powder (density approximately 7000 kg·m -3 The stagnant plate 14 was prepared by mixing a homogeneous mixture of materials, and the design density of the stagnant plate 14 was determined according to the design density (1425 kg m³). -3 The mixing ratio of silicone and iron powder was determined to be 62.9 wt% : 37.1 wt%. Based on the model size and design density, appropriate amounts of silicone and iron powder were taken, thoroughly mixed, and placed in a 25 cm × 25 cm × 1 cm mold. The simulated material of the retention plate 14 was allowed to flow and form in the mold, which took about one week.

[0034] Step S1.3: Select two samples with a density of 1415 kg m³. -3 POM plastic rings with inner diameters of 2 cm and 3 cm and outer diameters of 3 cm and 4 cm are used to simulate plate holes 13. After the material simulating the retention plate 14 is formed in the mold, material with the same outer diameter as the POM plastic ring is cut out at two specific positions of the retention plate 14. Then, two POM plastic rings are inserted to simulate plate holes 13. After being left to stand for a while, the simulated material of the plate hole 13 is fully bonded to the surrounding simulated material of the retention plate 14.

[0035] Step S2: Constructing the experimental model and experimental process observation system Step S2.1: In the experimental model preparation stage, seal the first through-plate joint 7 at the bottom of the experimental cylinder 5. Pour the lower mantle 4 simulation material and the upper mantle 3 simulation material into the experimental cylinder according to the preset parameters, and allow it to stand for a while to allow the air bubbles in the upper and lower mantle simulation materials to completely dissipate. This process generally takes several days. During this period, water is sprayed on the surface of the upper mantle 3 simulation material periodically according to the indoor humidity to prevent the glucose syrup surface from dehydrating and crystallizing to form a film that interferes with the dissipation of air bubbles inside the glucose syrup. Step S2.2: After the air bubbles inside the upper and lower mantle have been completely expelled, connect the plastic conduit 8 to the first through-plate connector 7 and the second through-plate connector 9 respectively; Step S2.3: Inject mantle plume simulation material 10 into the container, and the mantle plume simulation material 10 fills the plastic conduit 8 under the action of gravity; Step S2.4: Adjust the height of the lifting platform 11 so that the liquid level of the mantle column simulation material 10 inside the container is slightly higher than the liquid level of the upper mantle 3 inside the experimental tank 5, with a height difference of [missing information]. in, The height of the mantle column simulating the material inside the container. To simulate the thickness of the material in the lower mantle, The thickness of the simulated material in the upper mantle, To simulate the density of materials in the lower mantle, To simulate the density of materials in the upper mantle, The density of mantle plume simulation material 10 can be used to calculate the height difference. The mass is approximately 0.4 cm. At this point, the pressure head of the mantle plume simulation material 10 in the container is equal to the total pressure head of the upper and lower mantle simulation materials. The mantle plume simulation material 10 does not flow into the experimental cylinder 5. Record the reading of the electronic scale at this point, which represents the initial mass of the mantle plume simulation material 10 in the container. Step S2.5: After all the simulation materials are prepared, set up a high-definition camera around the experimental tank 5 and turn on the timed photo function to record the subsequent experimental process. In this embodiment, a side-view camera, a low-view camera, and a high-view camera were deployed, with a shooting time interval of 10 seconds. A side-view camera was used to observe the overall profile morphological evolution of the stagnant plate 14 and the generated mantle plume at a 660 km level discontinuity. Figure 4 A side-view evolution diagram taken by a side-view camera; The camera was used to observe the lateral diffusion process of the generated mantle plume at the bottom of the stagnant plate 14 and its passage through the plate hole 13. Figure 5 An image showing the evolution of the material from a low-angle perspective, taken with a camera looking upwards. The lateral diffusion process of the generated mantle plume after reaching the upper surface of the upper mantle 3 was observed by a top-down camera, resulting in a planar evolution diagram of the generated mantle plume's diffusion on the Earth's surface (image not shown).

[0036] Step S3: Place the retention plate and allow it to settle to the 660 km discontinuity. In the initial stage of the experiment, the pre-formed retention plate 14 with pores was placed at the initial position 1 of the retention plate on the upper surface of the upper mantle 3. Due to the surface tension of the glucose syrup, the denser retention plate 14 floated on the less dense upper mantle 3. A small amount of 80wt% glucose syrup was added to the retention plate 14 to cause it to begin settling, gradually settling at the preset settling position 2 on the 660km discontinuity surface. This process is as follows: Figure 4 As shown in AC.

[0037] Step S4: Start supplying mantle plume simulation material 10 to the bottom of the experimental tank and record the flow rate. Raise the height of the lifting platform 11 so that the pressure head of the mantle plume simulation material 10 in the container is higher than the total pressure head of the upper and lower mantle in the experimental cylinder 5. The mantle plume simulation material 10 is injected into the experimental cylinder from the first through-plate joint 7 at the bottom of the experimental cylinder through the plastic conduit 8. Subsequently, the readings of the electronic scale 12 were recorded at specific time intervals to obtain the container mass at different times. Then, the outflow mass of the mantle plume simulation material 10 at different times was calculated, and the mass flow rate of the mantle plume simulation material at different times was calculated based on the cross-sectional area of ​​the plastic conduit. Then, based on the density of the mantle plume simulation material, the outflow volume and volumetric flow rate were calculated, corresponding to the mass flow rate and volumetric flow rate of the mantle plume generated in the experimental cylinder.

[0038] Step S5: Observe and record the deformation characteristics and timing of key structural events. Once the mantle plume begins to flow into the bottom of the experimental chamber, key tectonic events and the timing of their occurrence are observed and recorded. Figure 4 and Figure 5 These are side and top views of the experimental simulation process, respectively, reflecting the evolution of the interaction between the mantle plume, the retained slab, and the slab cavity.

[0039] like Figure 4 As shown, the side view evolution of the experimental simulation process reflects multiple tectonic events in the interaction process of the mantle plume-retained slab-slab cavity: Figure 4 In the D-reflection model, mantle plume simulation material 10 is injected, and the mantle plume gradually forms and the head of the mantle plume gradually increases in size. Figure 4 E in the figure reflects the gradual stabilization of the mantle plume's shape in the lower mantle 4, forming a relatively wide head and a relatively slender tail. Figure 4 The F in the figure reflects that the mantle plume has just surged to the bottom of the stagnant plate 14 and has begun to spread laterally from the stagnant plate 14; Figure 4 The GH in the middle reflects the mantle plume spreading under the stagnant plate 14 to the two plate holes 13, and then rising through the plate holes 13 to the upper mantle 3. At this time, the right mantle plume branch has risen to the upper surface of the upper mantle 3 and spread laterally on a small scale. Figure 4 The "I" in the figure reflects the upwelling of the left-hand mantle plume to the upper surface of the upper mantle 3, followed by small-scale lateral diffusion. Due to mantle convection caused by the two mantle plume branches in the upper mantle, the two plume branches exhibit tail bending. Furthermore, Figure 4 The FI in the figure reflects the buoyancy lift effect of the mantle plume on the middle part of the stagnant plate 14.

[0040] like Figure 4 As shown, the evolution of the experimental simulation process from bottom to top reflects the contact process between the mantle plume and the stagnant plate, as well as the lateral diffusion process of the mantle plume beneath the stagnant plate: Figure 4A in the figure reflects the shape of the mantle plume and the two holes 13 in the mantle plate before the generated mantle plume comes into contact with the mantle plate 14. At this time, the mantle plate 14 is relatively flat. Figure 4 B in the figure reflects the moment when the upwelling mantle plume just comes into contact with the retention plate 14, and the buoyancy of the mantle plume causes the middle part of the retention plate 14 to rise. Figure 5 C in the figure reflects the lateral diffusion of the mantle plume beneath the stagnant plate 14, and its arrival at the right-side plate hole 13 first; Figure 5 D in the figure reflects the mantle plume rising up into the upper mantle 3 through the slab hole 13 on the right side of the stagnant slab 14; Figure 5 E in the figure reflects the mantle plume surging up into the upper mantle 3 through the slab hole 13 on the left side of the stagnant slab 14, while the right-side mantle plume branch has already undergone lateral diffusion on the upper surface of the upper mantle 3. It should also be noted that... Figure 5 The AE in the figure reflects that as the low-density mantle plume material accumulates below the retention plate 14, the buoyancy lifting effect of the mantle plume on the middle part of the retention plate 14 gradually increases, and the middle part of the retention plate 14 gradually bulges up, causing the plate holes 13 on both sides of the retention plate to change from horizontal to inclined, which to some extent leads to the bending phenomenon of the mantle plume branches.

[0041] Step S6: Stop supplying mantle plume simulation material to the bottom of the experimental cylinder. Step S6.1: After all the key structural events in the experimental simulation have been completed, lower the height of the lifting platform 11 so that the liquid level of the simulated mantle plume material inside the container is slightly higher than the liquid level of the upper mantle 3 inside the experimental cylinder 5, with a height difference of [missing information]. ; in, The height of the remaining mantle plume material inside the container after the critical tectonic event. The thickness of the lower mantle after the critical tectonic event. The thickness of the upper mantle after the critical structural event ends is the mantle plume simulation material in the container. At this time, the pressure head of the mantle plume simulation material in the container is equal to the total pressure head of the upper and lower mantle in the experimental cylinder. The mantle plume simulation material 10 does not flow into the experimental cylinder 5. Step S6.2: Record the reading of the electronic scale 12 at this time, which represents the mass of the remaining mantle plume simulation material 10 in the container. Combined with the initial mass recorded in step S2.4, calculate the total mass of the mantle plume simulation material 10 injected into the experimental cylinder 5. Combined with the density of the mantle plume simulation material and the continuous supply time, calculate the total volume and average volumetric flow rate of the mantle plume simulation material 10 injected into the experimental cylinder, and the corresponding total volume and average volumetric flow rate of the generated mantle plume.

[0042] Step S7: Observe and record the subsequent deformation characteristics and the time of occurrence. like Figure 5 J and Figure 5 Figure 5 Figure 4 Figure 5As shown in F, after the mantle plume simulation material 10 stops being injected into the experimental cylinder, the mantle plume gradually becomes thinner from bottom to top, and the two mantle plume branches in the upper mantle 3 have spread laterally to a large extent on the upper surface of the upper mantle 3.

[0043] After the experiment, the timed photo-taking function of all cameras was turned off, and photos from different perspectives were copied for subsequent simulation result analysis.

[0044] Retrieve the retention plate 14 from the experimental tank and remove the POM plastic ring. Wash the surface of the retention plate 14 and the POM plastic ring with running water to remove the glucose syrup (hot water is better) so that it can be reused in subsequent experiments. Then remove the plastic conduit 8 and plug the first through-plate joint 7 at the bottom of the experimental tank. After standing for a sufficient time (usually several days), wait for all the mantle plume material in the experimental tank 5 to float to the upper surface of the upper mantle 3. Retrieve all the mantle plume material from the experimental tank. Since some upper and lower mantle material will be lost in the experimental tank during the retrieval of the retention plate 14 and the mantle plume, it is necessary to replenish an appropriate amount of upper and lower mantle material into the experimental tank 5 after the experiment. After standing for a while, the two can naturally separate into layers, which is convenient for the next experiment.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A simulation device for the interaction between a mantle plume, a retained plate, and a plate cavity, characterized in that, Including the main experimental setup and the retention plate (14); The main experimental apparatus includes an experimental cylinder (5) and a geological model, a mantle plume simulation device, a lifting platform (11), and an electronic scale (12) inside the cylinder. The geological model inside the experimental cylinder includes the upper mantle (3) and the lower mantle (4), which are arranged in the experimental cylinder in a layered manner. The mantle plume simulation device includes a container and mantle plume simulation material (10) arranged inside the container. The simulation materials of the upper mantle, lower mantle and mantle plume are made of glucose syrup of different concentrations. The side of the mantle plume container is connected to a plastic conduit (8) through a second through-plate connector (9), and the other end of the plastic conduit is connected to the bottom of the experimental cylinder through a first through-plate connector (7). The lifting platform is used to adjust the height of the container to control the pressure head of the mantle plume simulation material; the lifting platform is placed on an electronic scale, which is used to monitor the mass change inside the container in real time and then quantitatively calculate the inflow rate of the mantle plume simulation material. The retention plate is placed in the upper mantle and has multiple circular holes. POM plastic rings are inserted into the circular holes to simulate the holes in the plate (13). The retention plate is subjected to negative buoyancy in the upper mantle.

2. The simulation device according to claim 1, characterized in that, The viscosity of the corresponding simulated materials for the mantle plume, upper mantle, lower mantle, and stagnant plate increases sequentially, and the plate cavity is a rigid body; the density of the corresponding simulated materials for the mantle plume, upper mantle, stagnant plate, plate cavity, and lower mantle increases sequentially.

3. The simulation device according to claim 1, characterized in that, The retention plates are made of a uniformly mixed mixture of silica gel and iron powder in a specific ratio. After the iron powder-silica gel mixture reaches a density and viscosity between that of the upper and lower mantle, it is placed in a mold of the designed size for leveling and shaping. Circular holes are cut out on the retention plates, and POM plastic rings are inserted to simulate the plate holes. The plates are left to stand for a while to allow the plate holes to fully adhere to the surrounding retention plates.

4. A method for simulating the interaction between a mantle plume, a retained plate, and a plate cavity based on the simulation device described in claim 1, characterized in that, Includes the following steps: Step S1: Determine the material and dimensional parameters of each component in the simulation device based on the geometric dimensions, rheological strength, and density or buoyancy parameters of the geological prototype to be simulated, and then manufacture it. Step S2: Assemble the simulation device. After the simulation device is stable, the middle of the upper surface of the upper mantle is used as the initial position of the retention plate (1). The interface between the upper and lower mantle is simulated as a 660 km discontinuity. The middle of the 660 km discontinuity is the preset settlement position of the retention plate (2). High-definition cameras are set up around the simulation device from different shooting angles to form an experimental process observation system, and the timed shooting function is turned on to record the subsequent experimental process. Step S3: In the initial stage of the experiment, the retained plate containing the plate hole is placed in the initial position; the retained plate begins to settle in the upper mantle and gradually settles to the preset settlement position; Step S4: Adjust the height of the lifting platform so that the pressure head of the mantle plume simulation material in the container is higher than the total pressure head of the upper and lower mantle in the experimental cylinder. Start supplying mantle plume simulation material to the bottom of the experimental cylinder through the first through-plate joint and generate mantle plumes. Record the mass change of the mantle plume simulation material and calculate the volume change through an electronic scale. Step S5: Observe and record the deformation characteristics and timing of key structural events; Step S6: Lower the height of the lifting platform and stop supplying mantle plume simulation material to the bottom of the experimental cylinder to simulate the natural extinction process of the mantle plume. Step S7: Observe and record the subsequent deformation characteristics and the time of occurrence.

5. The simulation method according to claim 4, characterized in that, Step S2 specifically includes: Step S21: Seal the first through-plate joint at the bottom of the experimental cylinder, and pour the following materials into the experimental cylinder according to the preset parameters, with a thickness of [missing information]. Density is The lower mantle and its thickness are Density is The upper mantle was allowed to settle completely to expel internal air bubbles, and the upper and lower mantles were allowed to stabilize completely. Step S22: Connect the plastic conduit to the first through-plate connector and the second through-plate connector respectively; Step S23: Inject a density of [amount] into the container. The mantle plume simulation material is filled with plastic conduits under the influence of gravity; Step S24: Adjust the height of the lifting platform so that the liquid level of the mantle plume simulation material inside the container is slightly higher than the upper mantle liquid level inside the experimental tank, with a height difference of [missing information]. At this point, the pressure head of the mantle plume simulation material in the container is equal to the total pressure head of the upper and lower mantle, and the mantle plume simulation material just does not flow into the experimental cylinder. Record the reading of the electronic scale at this point, which represents the initial mass of the mantle plume simulation material in the container. Step S25: Set up high-definition cameras around the experimental tank from different shooting angles, and turn on the timed shooting function to record the subsequent experimental process.

6. The simulation method according to claim 4, characterized in that, Step S4 involves recording the mass change and calculating the volume change of the simulated mantle plume material, specifically as follows: The readings of the electronic scale are recorded at specific time intervals to obtain the mass of the simulated mantle plume material in the container at different times. Then, the outflow mass of the simulated mantle plume material at different times is calculated, and the mass flow rate of the simulated mantle plume material through the conduit at different time periods is calculated. Based on the density of the simulated mantle plume material, the outflow volume and volumetric flow rate of the simulated mantle plume material are calculated, corresponding to the mass flow rate and volumetric flow rate of the mantle plume generated in the experimental cylinder.

7. The simulation method according to claim 4, characterized in that, Key tectonic events in step S5 include the gradual formation of the mantle plume head, the gradual formation of the mantle plume tail, the mantle plume head contacting the bottom of the stagnant plate, the mantle plume spreading laterally at the bottom of the stagnant plate, the mantle plume surging up through the plate hole in the stagnant plate to the upper mantle, and the branch mantle plumes of the upper mantle surging up to the upper surface of the upper mantle and spreading laterally.

8. The simulation method according to claim 5, characterized in that, Step S6 specifically includes: Step S61: After all the key structural events in the experimental simulation have been completed, lower the height of the lifting platform so that the liquid level in the container is slightly higher than the upper mantle liquid level, with a height difference of [missing information]. ； in, The height of the remaining mantle plume material inside the container after the critical tectonic event. The thickness of the lower mantle after the critical tectonic event. The thickness of the upper mantle after the critical tectonic event has ended, at which point the simulated mantle plume material is just not flowing into the experimental cylinder; Step S62: Record the reading on the electronic scale at this time, which represents the mass of the remaining mantle plume simulation material in the container. Combined with the initial mass recorded in step S24, calculate the total mass of the mantle plume simulation material injected into the experimental cylinder. Combined with the density of the mantle plume simulation material and the continuous supply time, calculate the total volume and average volumetric flow rate of the mantle plume simulation material injected into the experimental cylinder, and the corresponding total volume and average volumetric flow rate of the generated mantle plume.

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