The Research Status and Major Problems of High Temperature and High Pressure Experiment on Petrogenesis and mineralization

1 Introduction In contrast,1experimental geochemistry is a young subject,but in recent years,the research on experiment of high temperature and high pressure has become an important branch in the parallel subjects of traditional mineralogy,petrology,geochemistry and geophysics.It is not only an important and essential way and window to understand geological processes in depth and geological

An Experimental Study on Atmospheric Pressure Glow Discharge in Different Gases

Usually, the electrical breakdown of dielectric barrier discharge (DBD) at atmo-spheric pressure leads to a filamentary non-homogeneous discharge. However, it is also possible to obtain a diffuse DBD in homogeneous form, called atmospheric pressure glow discharge (APGD). We obtained a uniform APGD in helium and in the mixture of argon with alcohol, and studied the electrical characteristics of helium APGD. It is found that the relationship between discharge current and source frequency is different depending on the difference in gas gap when the applied voltage is kept constant. The discharge current shows an increasing trend with the increased frequency when gas gap is 0.8 cm, but the discharge current tends to decrease with the increased frequency when the gas gap increases. The discharge current always increases with the increased applied voltage when the source frequency is kept constant. We also observed a glow-like discharge in nitrogen at atmospheric pressure.

Structural Phase Transitions of ZnTe under High Pressure Using Experiments and Calculations

The pressure-induced structural transitions of ZnTe are investigated at pressures up to 59.2 GPa in a diamond anvil cell by using synchrotron powder x-ray diffraction method. A phase transition from the initial zinc blende （ZB, ZnTe-Ⅰ） structure to a cinnabar phase （ZnTe-Ⅱ） is observed at 9.6 GPa, followed by a high pressure orthorhombic phase （ZnTe-Ⅲ） with Cmcm symmetry at 12.1 GPa. The ZB, cinnabar （space group P3121）, Cmcm, P31 and rock salt structures of ZnTe are investigated by using density functional theory calculations. Based on the experiments and calculations, the ZnTe-Ⅱ phase is determined to have a cinnabar structure rather than a P3 1 symmetry.

Upper Limit for Rheological Strength of Crust in Continental Subduction Zone:Constraints Imposed by Laboratory Experiments

The transitional pressure of quartz coesite under the differential stress and highly strained conditions is far from the pressure of the stable field under the static pressure. Therefore, the effect of the differential stress should be considered when the depth of petrogenesis is estimated about ultrahigh pressure metamorphic (UHPM) rocks. The rheological strength of typical ultrahigh pressure rocks in continental subduction zone was derived from the results of the laboratory experiments. The results indicate the following three points. (1) The rheological strength of gabbro, similar to that of eclogite, is smaller than that of clinopyroxenite on the same condition. (2) The calculated strength of rocks (gabbro, eclogite and clinopyroxenite) related to UHPM decreases by nearly one order of magnitude with the temperature rising by 100 ℃ in the range between 600 and 900 ℃. The calculated strength is far greater than the faulting strength of rocks at 600 ℃, and is in several hundred to more than one thousand mega pascals at 700-800 ℃, which suggests that those rocks are located in the brittle deformation region at 600 ℃, but are in the semi brittle to plastic deformation region at 700-800 ℃. Obviously, the 700 ℃ is a brittle plastic transition boundary. (3) The calculated rheological strength in the localized deformation zone on a higher strain rate condition (1.6×10 -12 s -l ) is 2-5 times more than that in the distributed deformation zone on a lower strain rate condition (1.6×10 -14 s -1 ). The average rheological stress (1 600 MPa) at the strain rate of 10 -12 s -1 stands for the ultimate differential stress of UHPM rocks in the semi brittle flow field, and the average rheological stress (550-950 MPa) at the strain rate of l0 -14 - 10 -13 s -l stands for the ultimate differential stress of UHPM rocks in the plastic flow field, suggesting that the depth for the formation of UHPM rocks is more than 20-60 km below the depth estimated under static pressure condition due to the effect of the differential stress.

Experimental Study on Tensile Behavior of Cement Paste, Mortar and Concrete under High Strain Rates

Effects of the strain rate on cement paste, mortar and concrete were studied. A modified SHPB testing technique with fl attened Brazilian disc（FBD） specimen was developed to measure the dynamic tensile stress-strain curve of materials. A pulse-shaped split Hopkinson pressure bar（SHPB） was employed to determine the dynamic tensile mechanical responses and failure behavior of materials under valid dynamic testing conditions. Quasi-static experiments were conducted to study material strain rate sensitivity. Strain rate sensitivity of the materials was measured in terms of the stress-strain curve, elastic modulus, tensile strength and critical strain at peak stress. Empirical relations between dynamic increase factor（DIF） and the material properties were derived and presented.

Compressional elastic wave velocities of serpentinized pyroxenite at high pressures and high temperatures and its geological significance

Center for Analysis and Prediction, China Seismological Bureau, Beijing 100036, China 2) Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China

Modeling, analysis, and screening of cyclic pressure pulsing with nitrogen in hydraulically fractured wells

Cyclic pressure pulsing with nitrogen is studied for hydraulically fractured wells in depleted reservoirs.A compositional simulation model is constructed to represent the hydraulic fractures through local-grid refinement.The process is analyzed from both operational and reservoir/hydraulic-fracture perspectives.Key sensitivity parameters for the operational component are chosen as the injection rate,lengths of injection and soaking periods and the economic rate limit to shut-in the well.For the reservoir/hydraulic fracturing components,reservoir permeability,hydraulic fracture permeability,effective thickness and half-length are used.These parameters are varied at five levels.A full-factorial experimental design is utilized to run 1250 cases.The study shows that within the ranges studied,the gas-injection process is applied successfully for a 20-year project period with net present values based on the incremental recoveries greater than zero.It is observed that the cycle rate limit,injection and soaking periods must be optimized to maximize the efficiency.The simulation results are used to develop a neural network based proxy model that can be used as a screening tool for the process.The proxy model is validated with blind-cases with a correlation coefficient of 0.96.

Experimental study for frequency spectrum of turbulent boundary layer pressure fluctuation

An experimental study on TBL (turbulent boundary layer) pressure fluctuation frequeny spectrum of a revolution body is presented. With the measured results, a relation of convective frequency fo of the models is obtained. Relations of turbuleat wall-pressure fluctuation spectrum in transition region and development region to frequency and speed are obtained also

Experimental analysis of considering the sound pressure distribution pattern at the ear canal entrance as an unrevealed head-related localization clue

By analyzing the differences between binaural recording and real listening, it was deduced that there were some unrevealed auditory localization clues, and the sound pressure distribution pattern at the entrance of ear canal was probably a clue. It was proved through the listening test that the unrevealed auditory localization clues really exist with the reduction to absurdity. And the effective frequency bands of the unrevealed localization clues were in- duced and summed. The result of finite element based simulations showed that the pressure distribution at the entrance of ear canal was non-uniform, and the pattern was related to the direction of sound source. And it was proved that the sound pressure distribution pattern at the entrance of the ear canal carried the sound source direction information and could be used as an unrevealed localization clue. The frequency bands in which the sound pressure distribution patterns had significant differences between front and back sound source directions were roughly matched with the effective frequency bands of unrevealed localization clues obtained from the listening tests. To some extent, it supports the pattern could be a kind of unrevealed auditory hypothesis that the sound pressure distribution localization clues.

Fe-Mn interdiffusion in aluminosilicate garnets

Precise determination of cation diffusivity in garnet can provide critical information for quantitatively understanding the timescales and thermodynamics of various geological processes,but very few studies have been performed for Fe-Mn interdiffusion.In this study,Fe-Mn interdiffusion rates in natural single crystals of Mn-bearing garnet with 750 ppm H2O are determined at 6 GPa and 1273-1573 K in a Kawai-type multi-anvil apparatus.Diffusion profiles were acquired by electron microprobe and fitted using Boltzmann-Matano equation.The experimental results show that the Fe-Mn interdiffusion coefficient(DFe-Mn)slightly decreases with increasing XFe.The experimentally determined DFe-Mn in Mn-bearing garnet can be fitted by the Arrhenius equation:DFe-Mn(m2/s)=D0XFenexp(-E*/RT),where E*=(1-XFe)E*Mn+XFeE*Fe,D0=8.06-6.04+9.87×10-9 m2/s,E*Mn=248±27 KJ/mol,E*Fe=226±59 KJ/mol,n=-1.36±0.51.The comparing the present results with previous experimental data suggest that water can greatly enhance the DFe-Mn in garnet.Our results indicate that the time required for homogenization of the compositional zoning of a garnet is much shorter than previously thought.

Effect of the PTO damping force on the wave pressures on a 2-D wave energy converter

The information of the wave loads on a wave energy device in operational waves is required for designing an efficient wave energy system with high survivability. It is also required as a reference for numerical modeling. In this paper, a novel system, which integrates an oscillating wave energy converter with a pile-restrained floating breakwater, is experimentally investigated in a 2-D wave flume. The measurements of the wave pressure on the wet-surface of the device are made as the function of the power take-off（PTO） damping force. It is shown that the wave pressure is significantly affected by the PTO system, in particular, at the edges, and the wave pressure varies under different wave conditions. From the results, conclusions can be drawn on how the PTO damping force and wave conditions affect the loads on the device, which is of engineering concern for constructing safe and reliable devices.

Crystallization of Hydrous Ti-Rich Basaltic Magma and Its Implication for the Origin of Fe-Ti Oxide in Layered Intrusions of the Emeishan Large Igneous Province

A series of crystallization experiments have been carried out by using natural Emeishan Ti-rich hydrous basalts as starting materials at a pressure of 0.5 GPa and temperatures of 800-1000℃to constrain the origin of Fe-Ti-V oxide ore deposits.Our experimental results demonstrate that the sandwich-and trellis-type ilmenite lamellae in titanomagnetite of layered intrusions can be formed by the reaction of earlier crystallized ilmenite and the evolved parental magma.During evolution of parental basaltic magma,the Fe-Ti oxide should be composed of titanomagnetite+ilmenite in the earlier stage,but changed to titanomagnetite+titanomagnetite-ilmenite intergrowth±ilmenite at the later stage.Accordingly,the Panzhihua Fe-Ti oxide ores,which are mainly composed of titanomagnetite,should be formed earlier than the adjacent gabbro,in which titanomagnetite-ilmenite intergrowth is the major form of the Fe-Ti oxide.