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Seismic tomography studies have revealed a high-velocity anomaly at depths between 100 km and 300 km in the Farallon plate. However, the reasons for the high-velocity anomaly continue to be debated. An analysis of the mineral proportions of eclogites exhumed from the Farallon plate shows that the average amount of zoisite in eclogite is ∼16.0 vol%. Therefore, the presence of zoisite eclogite needs to be considered to explain the high-velocity anomaly of the Farallon plate. However, the thermal equation of state and stability of zoisite have not been fully investigated under high pressure−temperature (P-T) conditions. We investigated the high-pressure and high-temperature behavior of natural zoisite utilizing synchrotron single crystal-X-ray diffraction (XRD). The results indicate that zoisite is metastable up to 24.8 GPa and 700 K. We obtained the ambient unit-cell volume V0 = 901.26(3) Å3 by synchrotron single crystal-XRD measurement. We also fitted the pressure-volume-temperature data to a high-temperature Birch-Murnaghan equation of state and obtained the zero-pressure bulk modulus K0 = 134.7(8) GPa, the temperature derivative of the bulk modulus (∂K/∂T)P = −0.011(4) GPa/K, and the thermal expansion coefficients α0V = 1.9(7) × 10−5 K−1 and α1V = 3(2) × 10−8 K−2 when the pressure derivative of bulk modulus (K′0) is fixed at 4. By incorporating the results from previous studies, we calculated the density and bulk sound velocity profiles of zoisite eclogite along the Farallon plate geotherm. Finally, we infer that zoisite could carry water to depths of ∼300 km within cold subducting slabs and that the bulk sound velocity of typical zoisite eclogite with ∼61.0 vol% omphacite, ∼23.0 vol% garnet, and ∼16.0 vol% zoisite could cause the high-velocity anomalies at depths of 100−300 km in the Farallon plate.

Mesozoic intermediate-felsic magmatic rocks in the eastern North China Craton commonly show geochemical similarity to adakites. However, the lack of direct constraints from partial melting experiments at high pressures and temperatures fuels a debate over the origin of these rocks. In this work, we performed partial melting experiments at 1.5 ​GPa and 800–950 ​°C on amphibolite samples collected from the vicinity of the Mesozoic potassium-rich adakitic rocks in the Zhangjiakou area, northern margin of the North China Craton. The experimental melts range from granitic to granodioritic compositions, with SiO2 ​= ​56.4–72.6 ​wt.%, Al2O3 ​= ​16.1–19.3 ​wt.%, FeO∗ ​= ​2.4–9.6 ​wt.%, MgO ​= ​0.3–2.0 ​wt.%, CaO ​= ​0.6–3.8 ​wt.%, Na2O ​= ​4.7–5.3 ​wt.%, and K2O ​= ​2.6–3.9 ​wt.%, which are in the ranges of the surrounding Mesozoic potassium-rich adakitic rocks, except for the higher Al2O3 contents and the data point at 1.5 ​GPa and 800 ​°C. Trace element compositions of the melts measured by LA-ICP-MS are rich in Sr (849–1067 ​ppm) and light rare earth elements (LREEs) and poor in Y (

Epidote is a typical hydrous mineral in subduction zones. Here, we report a synchrotron-based single-crystal X-ray diffraction (XRD) study of natural epidote [Ca1.97Al2.15Fe0.84(SiO4)(Si2O7)O(OH)] under simultaneously high pressure-temperature (high P-T) conditions to ~17.7 ​GPa and 700 ​K. No phase transition occurs over this P-T range. Using the third-order Birch-Murnaghan equation of state (EoS), we fitted the pressure-volume-temperature (P-V-T) data and obtained the zero-pressure bulk modulus K0 ​= ​138(2) GPa, its pressure derivative K 0 ' ​= ​3.0(3), the temperature derivative of the bulk modulus ((∂K/∂T)P ​= ​−0.004(1) GPa/K), and the thermal expansion coefficient at 300 ​K (α0 ​= ​3.8(5) ​× ​10−5 ​K−1), as the zero-pressure unit-cell volume V0 was fixed at 465.2(2) A3 (obtained by a single-crystal XRD experiment at ambient conditions). This study reveals that the bulk moduli of epidote show nonlinear compositional dependence. By discussing the stabilization of epidote and comparing its density with those of other hydrous minerals, we find that epidote, as a significant water transporter in subduction zones, may maintain a metastable state to ~14 ​GPa along the coldest subducting slab geotherm and promote slab subduction into the upper mantle while favoring slab stagnation above the 410 ​km discontinuity. Furthermore, the water released from epidote near 410 ​km may potentially affect the properties of the 410 ​km seismic discontinuity.

The thermoelastic properties of minerals in mantle xenoliths combined with the thermal states can provide an integrated understanding of the petrophysics of the lithospheric mantle. Here, we conducted high-pressure and high-temperature experiments on the main minerals (e.g. olivine, orthopyroxene, clinopyroxene, spinel, and garnet) in peridotite xenoliths from basalt of the eastern North China Craton (NCC) using in situ synchrotron single-crystal X-ray diffraction combined with diamond anvil cells. The pressure-temperature-volume data were fitted to the third-order Birch-Murnaghan equations of state and yielded the thermoelastic parameters that included bulk modulus, pressure and temperature derivatives, and thermal expansion coefficients. The density profiles of the eastern NCC during the destruction process since the Mesozoic are presented from the temporal and spatial aspects. The lithospheric density dramatically decreased during destruction, and high heat flow may have been a trigger. The spatially distributed density profile also provides firm evidence for lateral heterogeneities in the eastern NCC. This may suggest that the present mantle is characterized by heterogeneous destruction of the NCC.

Olivine is the most abundant mineral in the Earth's upper mantle and subducting slabs. Studying the structural evolution and equation of state of olivine at high-pressure is of fundamental importance in constraining the composition and structure of these regions. Hydrogen can be incorporated into olivine and significantly influence its physical and chemical properties. Previous infrared and Raman spectroscopic studies indicated that local structural changes occur in Mg-rich hydrous olivine (Fo ≥ 95; 4883–9000 ppmw water) at high-pressure. Since water contents of natural olivine are commonly

The compressional behavior of strontianite SrCO3 was investigated at ambient temperature and high pressure, using a diamond anvil cell (DAC) with Ne as a pressure transmitting medium. X-ray diffraction patterns were collected to ~52 GPa using in situ angle-dispersive synchrotron-based powder X-ray diffraction (XRD). A phase transition was observed at ~20 GPa, and no indications of further transitions were detected up to ~52 GPa. The pressure-volume (P-V) data within 0.27-17.35 GPa were fitted to a third-order Birch-Murnaghan equation of state (BM3 EoS) to obtain the elastic coefficients including zero-pressure unit-cell volume, isothermal bulk modulus and its pressure derivative: V0 = 258.4(3) Å3, KT0 = 55(2) GPa, and K'T0 = 4.3(3). The V0 and KT0 were obtained as 258.1(2) Å3 and 57.1(6) GPa, when fixed K'T0 = 4. The axial compressional behavior of strontianite was also investigated by fitting the pressure-lattice parameter data to a parameterized form of the BM3 EoS, and the compression of the a-, b-, and c-axis was strongly anisotropic, with Ka0 = 104(6), Kb0 = 52(12), and Kc0 = 31.6(5) GPa. Based on this and previous studies using different pressure transmitting media (PTM), the effects PTM on the compressional behavior of strontianite were discussed.

Tibet, which is characterized by collisional orogens, has undergone the process of delamination or convective removal. The lower crust and mantle lithosphere appear to have been removed through delamination during orogenic development. Numerical and analog experiments demonstrate that the metamorphic eclogitized oceanic subduction slab or lower crust may promote gravitational instability due to its increased density. The eclogitized oceanic subduction slab or crustal root is believed to be denser than the underlying mantle and tends to sink. However, the density of eclogite under high-pressure and high-temperature conditions and density differences from the surrounding mantle is not preciously constrained. Here, we offer new insights into the derivation of eclogite density with a single experiment to constrain delamination in Tibet. Using in situ synchrotron X-ray diffraction combined with diamond anvil cell, experiments focused on minerals (garnet, omphacite, and epidote) of eclogite are conducted under simultaneous high-pressure and high-temperature conditions, which avoids systematic errors. Fitting the pressure-temperature-volume data with the third-order Birch-Murnaghan equation of state, the thermal equation of state (EoS) parameters, including the bulk modulus (KT0), its pressure derivative (KT0′), the temperature derivative ((KT/T)P), and the thermal expansion coefficient (α0), are derived. The densities of rock-forming minerals and eclogite are modeled along with the geotherms of two types of delamination. The delamination processes of subduction slab breakoff and the removal of the eclogitized lower crust in Tibet are discussed. The Tibetan eclogite which containing 40–60 vol. % garnet and 37–64 % degrees of eclogitization can promote the delamination of slab break-off in Tibet. Our results indicate that eclogite is a major controlling factor in the initiation of delamination. A high abundance of garnet, a high Fe-content, and a high degree of eclogitization are more conducive to instigating the delamination.

Barite is an abundant sulfate mineral in nature. Especially, the variety of morphologies of barite is often driven by the mixing of Ba-bearing hydrothermal fluid and sulfate-bearing seawater around hydrothermal chimneys. In order to better understand the factors affecting the morphology and precipitation mechanism(s) of barite in seafloor hydrothermal systems, we synthesized barite by a new method of in-situ mixing of BaCl2 and Na2SO4 solutions at 200 °C while varying Ba concentrations and ratios of Ba2+/SO42−, and at room temperature for comparison. The results show that barite synthesized by in-situ mixing of BaCl2 and Na2SO4 solutions at 200 °C forms a variety of morphologies, including rod-shaped, granular, plate-shaped, dendritic, X-shaped, and T-shaped morphologies, while room temperature barites display relatively simple, granular, or leaf-like morphologies. Thus, temperature affects barite morphology. Moreover, dendritic barite crystals only occurred at conditions where Ba2+ is in excess of SO42− at the experimental concentrations. The dendritic morphology of barite may be an important typomorphic feature of barite formed in high-temperature fluids directly mixing with excess Ba2+ relative to SO42−.

The elasticity of single-crystal hydrous pyrope with ~900 ppmw H2O has been derived from sound velocity and density measurements using in situ Brillouin light spectroscopy (BLS) and synchrotron X-ray diffraction (XRD) in the diamond-anvil cell (DAC) up to 18.6 GPa at room temperature and up to 700 K at ambient pressure. These experimental results are used to evaluate the effect of hydration on the single-crystal elasticity of pyrope at high pressure and high temperature (P-T) conditions to better understand its velocity profiles and anisotropies in the upper mantle. Analysis of the results shows that all of the elastic moduli increase almost linearly with increasing pressure at room temperature, and decrease linearly with increasing temperature at ambient pressure. At ambient conditions, the aggregate adiabatic bulk and shear moduli (KS0, G0) are 168.6(4) and 92.0(3) GPa, respectively. Compared to anhydrous pyrope, the presence of ~900 ppmw H2O in pyrope does not significantly affect its KS0 and G0 within their uncertainties. Using the third-order Eulerian finite-strain equation to model the elasticity data, the pressure derivatives of the bulk [(∂KS/∂P)T] and shear moduli [(∂G/∂P)T] at 300 K are derived as 4.6(1) and 1.3(1), respectively. Compared to previous BLS results of anhydrous pyrope, an addition of ~900 ppmw H2O in pyrope slightly increases the (∂KS/∂P)T, but has a negligible effect on the (∂G/∂P)T within their uncertainties. The temperature derivatives of the bulk and shear moduli at ambient pressure are (∂KS/∂T)P = –0.015(1) GPa/K and (∂G/∂T)P = –0.008(1) GPa/K, which are similar to those of anhydrous pyrope in previous BLS studies within their uncertainties. Meanwhile, our results also indicate that hydrous pyrope remains almost elastically isotropic at relevant high P-T conditions, and may have no significant contribution to seismic anisotropy in the upper mantle. In addition, we evaluated the seismic velocities (νP and νS) and the νP/νS ratio of hydrous pyrope along the upper mantle geotherm and a cold subducted slabs geotherm. It displays that hydrogen also has no significant effect on the seismic velocities and the νP/νS ratio of pyrope at the upper mantle conditions.

Partitioning behavior between amphibole and silicate glass of thirty-three minor and trace elements (Sc, Ti, V, Cr, Co, Rb, Sr, P, Y, Zr, Nb, Cs, Ba, K, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, Pb, Th, and U) have been determined experimentally. Products of crystallization of hydrous basalt melts from 0.6 GPa/860 °C up to 2.6 GPa/970 °C were obtained in a multi-anvil apparatus. Major and trace element compositions of amphibole and glass were determined with a combination of electron microprobe and laser ablation inductively coupled plasma mass spectrometry. The main mineral phase is calcic amphibole, and the coexisting glass compositions are tonalite, granodiorite, and granite. The compatibility of rare earth elements increase at 915 °C and then decrease at 970 °C, but the compatibility of most of these elements shows a continued, significant increase with increasing pressure. For high-field strength elements, large ion lithophile elements, actinide compatibility decrease with increasing temperature or pressure, but transition metals show a continued increase in compatibility within the temperature–pressure conditions. From mathematical and graphical fitting, we determined best-fit values for the ideal ionic radius (r0, 1.01–1.04 A), the strain-free partition coefficient (D0, 1.18–1.58), and apparent Young’s modulus (E, 142–370 GPa) for the M4 site in amphibole according to the lattice strain model. The $$D_{0}^{M4}$$ for rare earth elements rises at 915 °C and then drops at 970 °C at 0.6 GPa. However, the $$D_{0}^{M4}$$ values are positively proportional to the pressure for rare earth elements in the amphibole-glass pairs at 0.6–2.6 GPa and 970 °C. Furthermore, the derived best-fit values for $$r_{0}^{M4}$$ and $$E^{M4}$$ are almost constant and trend to increase with rising temperature and pressure, respectively. The partition coefficient is distinctly different for different melt compositions. The rare earth elements become more enriched in amphibole if the quenched glass is granodiorite or granite compared to the tonalitic glasses.

Experimental studies on the phase transition and thermoelastic behavior of barite-group minerals are crucial to understand the recycle of sulfur in Earth’s interior. Here, we present a high-pressure and high-temperature (high P–T) study on two barite-group minerals—barite (BaSO4) and celestite (SrSO4) up to ~ 59.5 GPa 700 K and ~ 22.2 GPa, 700 K, respectively, using in situ synchrotron-based X-ray diffraction (XRD) combined with diamond anvil cells (DACs). Our results show that BaSO4 undergoes a pressure-induced phase transition from Pbnm to P212121 at ~ 20.3 GPa, which is different from the previous results. Upon decompression, the high-pressure phase of BaSO4 transforms back into its initial structure, which indicates a reversible phase transition. However, no phase transitions have been detected in SrSO4 over the experimental P–T range. In addition, fitting a third-order Birch–Murnaghan equation of state to the pressure–volume data yields the bulk moduli and their pressure derivatives of BaSO4 and SrSO4. Simultaneously, the thermal expansion coefficients of BaSO4 and SrSO4 are also obtained, by fitting the temperature-volume data to the Fei-type thermal equation of state. Furthermore, the compositional effects on the phase transformation and thermoelastic behavior of barite-group minerals are also discussed, and the results suggest that the bond length of (M=Ba, Sr, Pb) is an important factor that causes the phase transition pressure of SrSO4 to be the largest, PbSO4 is the second, and BaSO4 is the lowest.

The equation of state and stability of topaz at high-pressure/high-temperature conditions have been investigated by in situ synchrotron X-ray diffraction (XRD) and Raman spectroscopy in this study. No phase transition occurs on topaz over the experimental pressure&ndash, temperature (P-T) range. The pressure&ndash, volume data were fitted by the third-order Birch&ndash, Murnaghan equation of state (EoS) with the zero-pressure unit&ndash, cell volume V0 = 343.86 (9) &Aring, 3, the zero-pressure bulk modulus K0 = 172 (3) GPa, and its pressure derivative K&rsquo, 0 = 1.3 (4), while the obtained K0 = 155 (2) GPa when fixed K&rsquo, 0 = 4. In the pressure range of 0&ndash, 24.4 GPa, the vibration modes of in-plane bending OH-groups for topaz show non-linear changes with the increase in pressure, while the other vibration modes show linear changes. Moreover, the temperature&ndash, volume data were fitted by Fei&rsquo, s thermal equation with the thermal expansion coefficient &alpha, 300 = 1.9 (1) &times, 10&minus, 5 K&minus, 1 at 300 K. Finally, the P-T stability of topaz was studied by a synchrotron-based single-crystal XRD at simultaneously high P-T conditions up to ~10.9 GPa and 700 K, which shows that topaz may maintain a metastable state at depths above 370 km in the upper mantle along the coldest subducting slab geotherm. Thus, topaz may be a potential volatile-carrier in the cold subduction zone. It can carry hydrogen and fluorine elements into the deep upper mantle and further affect the geochemical behavior of the upper mantle.

Zoisite is a typical accessory mineral of eclogite; understanding its compressional behavior is important for the knowledge of the properties and processes within subduction zones. In this study, the compressional behavior of a natural eclogitic zoisite Ca1.99(Al2.87Fe0.11)Si3.00O12OH was investigated at ambient temperature and high pressure to 34 GPa, using a diamond anvil cell (DAC) combined with synchrotron-based single-crystal X-ray diffraction (XRD) method. Our results indicate that zoisite is stable over the experimental pressure range. The pressure–volume (P–V) data were fitted to a third-order Birch–Murnaghan equation of state (BM3 EoS), and the equation of state coefficients including zero-pressure unit-cell volume (V0), isothermal bulk modulus (KT0), and its pressure derivative ( $$K_{{T0}}^{\prime }$$ ) were obtained as: V0 = 904.77(8) A3, KT0 = 118(1) GPa, and $$K_{{T0}}^{\prime }$$ = 6.3(2), respectively. The axial compressibilities (β) for a-, b-, and c-axes were also obtained using a parameterized form of the BM3 EoS, and the results show βa0

The compressibility and expansivity of anglesite (PbSO4) have been measured at high pressure up to 21.6 GPa and high temperature up to 700 K using in situ angle-dispersive X-ray diffraction and diamond anvil cell. The third-order Birch–Murnaghan equation of state (III-BM-EoS) was used to analyze the pressure–volume (P–V) data of PbSO4. We obtained the bulk modulus K0 = 59(1) GPa, and its pressure derivative $$K_{0}^{'}$$ = 5.3(4), respectively. Using Holland–Powell thermal EoS to fit the temperature–volume (T–V) data, the thermal expansion coefficient α0 = 4.59(2) × 10− 5 K− 1 for PbSO4 was also derived. Simultaneously, the ambient-pressure axial compressibilities (βa0 = 1.79(4) × 10− 3 GPa− 1, βb0 = 1.75(5) × 10− 3 GPa− 1, βc0 = 2.12(4) × 10− 3 GPa− 1) and axial thermal expansivities (αa0 = 1.23(4) × 10− 5 K− 1, αb0 = 1.93(2) × 10− 5 K− 1, and αc0 = 1.43(1) × 10− 5 K− 1) along a-axis, b-axis and c-axis were derived at 300 K, respectively. Furthermore, the potential influencing factors (e.g., the effective size of M2+ cation, polarizability and electronegativity) on the bulk moduli of barite-type (belonging to Pbnm space group) sulfates (anglesite, barite, and celestine) were discussed. We found that the polarizability might be the most important factor. Finally, the anisotropic linear compressibility and thermal expansivity in barite-type sulfates were also discussed, respectively.

The phase transition and thermal equation of state of cadmium sulfide (CdS) were studied at high pressure and temperature conditions up to 21.9 GPa and 650 K, by using in situ synchrotron angle-dispersive X-ray diffraction and an externally-heated diamond anvil cell (DAC). A pressure-induced phase transition from wurtzite structure (WZ) to rocksalt structure (RS) was observed at about 2.6 GPa, which was agreed with previous studies (2.0–3.5 GPa). In addition, fitting of the experimental data by means of the third-order Brich-Murnaghan equation of state (III-BM EoS) gives the bulk modulus K0 = 81.6 (13) GPa, its pressure derivative K′0 = 3.68 (13), and the volumetric thermal expansion coefficient α0 = 2.97 (25) × 10−5 K−1 for RS phase of CdS. Simultaneously, the thermal expansion coefficient (α0 = 1.51 × 10−5 K−1), and its axial thermal expansivities (8.30 × 10−6 K−1 and 5.96 × 10−6 K−1) along a-axis and c-axis for WZ phase of CdS at ambient conditions were obtained, respectively. Moreover, it was found that the phase transition pressure from WZ (or ZB) type to RS type of cadmium chalcogenides (CdS, CdSe and CdTe) is quite similar by comparing their phase transition pressures. Furthermore, the elastic properties of metal sulfides (ZnS, CdS, HgS, PbS) with the same crystal structure but different metal cations were also discussed, and found that the bulk moduli for the RS phase of metal sulfides (ZnS, CdS, HgS, PbS) have a negative correlation with the cation radius, but a positive correlation with the electronegativity.

A new type of color-changing metallic glasses is discovered: the color can change continuously and spontaneously under ambient conditions. The colors are created mostly by the light interference in the surface metallic-oxide layer and partially by the optical bandgap energy of the formed yttrium-doped cerium oxide. Although metal oxidation is a natural consequence for most metals, this series of yttrium-doped and cerium-based metallic glasses are special because i) the oxidation is continuous, allowing color-changing; ii) the oxide layer is uniform in thickness avoiding stain and corrosion; and iii) the colors can change as fast as in days. The color-changing functionality is greatly connected to the oxygen affinity of the cerium constituent, the glassy structure devoid of grain boundaries, and the regulation from the yttrium dopant. This work not only demonstrates a new direction for metal oxidation but also points out new applications of metallic glass.

Femtosecond laser ionization time-of-flight mass spectrometry (fs-LI-TOFMS) is introduced for the three-dimensional elemental analysis of a Nantan meteorite. Spatially resolved multielemental imaging of major and minor compositions in a meteorite are presented with a lateral resolution of 50 μm and a depth resolution of 7 μm. Distinct 3D distributions of siderophile, lithophile, and chalcophile elements are revealed. Co and Ni are highly siderophile (Iron-loving), mainly enriched in the metal phase. Cr, Cu, V, and Mn are enriched in the sulfide for their chalcophile (S-loving) tendency. S, P, and C aggregate together in the analytical volume. Silicate inclusion, containing lithophile elements of Al, Ca, Mg, K, and so on, is embedded within the metal phase for the immiscibility between silicate inclusion and the melted metal phase. These 3D distributions of elements aid the exploration of the formation and evolution of the meteorite. They also reveal the feasibility of fs-LI-TOFMS as a versatile tool for 3D imaging.

Crystal-chemical properties of synthetic Almandine-Pyrope (Alm-Pyr) solid solutions were investigated by X-ray single-crystal diffraction and Raman spectroscopy. Garnet solid solution with different compositions were synthesized from powder at 4.0 GPa and annealed at 1200 &deg, C for 48 h by a multi-anvil pressure apparatus. Garnet crystals with different sizes (about 60-1000 &mu, m) were obtained from synthesis. The results of X-ray single-crystal diffraction show that the unit cell constants decrease with increasing Pyr contents in the synthetic Alm-Pyr crystals due to the smaller ionic radius of Mg2+ in eightfold coordination than that of Fe2+. The data exhibit obviously positive deviations from ideal mixing volumes across the Alm-Pyr join which may be caused by the distortion of the SiO4 tetrahedron. Moreover, the significant decrease in the average M-O bond length and volume of the [MgO8]/[FeO8] dodecahedron with increasing Pyr contents are the most important factors to the decrease in the Alm-Pyr crystal unit cell constant and volume. On the other hand, selected bond distances (average &lt, M-O&gt, &lt, Al-O&gt, and &lt, D-O&gt, distances) have a linear correlation with the unit-cell parameter, but the &lt, Si-O&gt, distance has nonlinear correlation. With increasing the unit-cell parameter, the average &lt, distance increases significantly, followed by the average &lt, distances. While the &lt, distance changes negligibly further confirming the conclusion that the significant decrease of the average M-O bond length of the [MgO8]/[FeO8] dodecahedron with increasing Pyr contents are the most important factors to the decrease in the Alm-Pyr crystal unit cell volume. In the Raman spectra collected for the Alm-Pyr solid solutions, Raman vibration mode assignments indicate that the Raman vibrational spectra change along the Alm-Pyr binary solution. The mode frequencies of Si-O stretching, Si-O bending, and the rotation of the SiO4-tetrahedron (R(SiO4)) decrease linearly, while the translational modes of the SiO4-tetrahedron (T(SiO4)) increase with increasing Alm contents.

We carried out three series of amphibole crystallization experiments from hydrous basaltic melt to calibrate the dependence of crystal growth rate on temperature and pressure in amphibole-bearing igneous rocks. One series of 100 h duration multi-anvil experiments were carried out at a constant pressure of 0.6 GPa and variable temperatures from 860 to 970 °C. The second series was conducted at a constant temperature of 970 °C and variable pressures from 0.6 to 2.6 GPa. The third series examined the time dependence at 970 °C and 0.6 GPa, with durations from 1 to 100 h. A verification experiment showing both reproducibility and the ability of these three series to predict behavior at novel conditions was performed in a piston cylinder at 1.0 GPa and 900 °C for 63 h. All experiments yielded mostly amphibole in a quenched glass of granitic to granodioritic composition. We used the two-dimensional thin section method to measure the crystal size distribution (CSD) of amphibole in the experimental products. Concave-down CSD curves at small sizes indicate a textural coarsening process during the crystallization. The CSD data were inverted using canonical CSD theory for CSD growth rate; maximum and average growth rates of amphibole were also inferred directly from the maximum and average grain size and crystallization time. The maximum growth rate is, of course, always larger than the average growth rate, which is in turn slightly larger than the CSD growth rate, suggesting that CSD growth rate is an adequate measure of the average growth rate of a mineral in magmatic rocks. The CSD growth rate increases with increasing temperature in the isobaric series and with increasing pressure at constant temperature. However, the growth rate is negatively correlated with crystallization time at constant temperature and pressure. Based on the experimental results, a functional form for evaluating growth rate at known pressure and temperature from an observed amphibole CSD was developed and applied to a diorite collected from the eastern Tianshan Mountains, Xinjiang Uygur autonomous region, NW China. The estimated growth rate of amphibole is between 1.6 × 10^(–9) mm/s and 5.6 × 10^(–7) mm/s, and combined with petrological constraints on pressure and temperature, the corresponding crystallization time was between 0.1 and 4.3 yr in the natural diorite.

The pressure–volume–temperature (P–V–T) equation of state (EoS) of synthetic grossular (Grs)–andradite (And) solid-solution garnet sample have been measured at high temperature up to 900 K and high pressures up to 22.75 GPa for Grs50And50, by using in situ angle-dispersive X-ray diffraction and diamond anvil cell. Analysis of room-temperature P–V data to a third-order Birch–Murnaghan (BM) EoS yields: V 0 = 1706.8 ± 0.2 A3, K 0 = 164 ± 2 GPa and K′ 0 = 4.7 ± 0.5. Fitting of our P–V–T data by means of the high-temperature third-order BM EoS gives the thermoelastic parameters: V 0 = 1706.9 ± 0.2 A3, K 0 = 164 ± 2 GPa, K′ 0 = 4.7 ± 0.2, (∂K/∂T) P = −0.018 ± 0.002 GPa K−1, and α 0 = (2.94 ± 0.07) × 10−5 K−1. The results also confirm that grossular content increases the bulk modulus of the Grs-And join following a nearly ideal mixing model. The relation between bulk modulus and Grs mole fraction (X Grs) in this garnet join is derived to be K 0 (GPa) = (163.7 ± 0.7) + (0.14 ± 0.02) X Grs (R 2 = 0.985). Present results are also compared to previously studies determined the thermoelastic properties of Grs-And garnets.

The high-pressure properties of natural azurite [Cu3(CO3)2(OH)2] have been investigated by in situ synchrotron powder X-ray diffraction and Raman spectroscopy up to 11 and 16 GPa at room temperature, respectively. The results indicate that azurite is stable within the pressure region in this study. The pressure–volume data from in situ X-ray diffraction experiments were described by a third-order Birch–Murnaghan equation of state with V 0 = 304.5 (4) A3, K 0 = 40 (2) GPa and K 0′ = 5.5 (6). The K 0 was obtained as 45.1 (8) GPa when K 0′ was fixed at 4. The axial compressional behavior of azurite was also fitted with a linearized third-order Birch–Murnaghan equation of state, showing an intense anisotropy with K a0 = 29.7 (9) GPa, K b0 = 25.0 (7) GPa and K c0 = 280 (55) GPa. In addition, the Raman spectroscopy of azurite in this study also presents the weak [OH]− group and the rigid [CO3]2− group. The different high-pressure behaviors of azurite and malachite combined with the smaller isothermal bulk modulus compared with certain anhydrous carbonates and the obvious compression anisotropy of azurite were discussed with the experimental results in this study together with the results from previous studies. Furthermore, the effect of hydroxyl on the high-pressure behaviors of carbonates was also discussed.

High pressure X-ray diffraction experiments on mimetite [Pb5(AsO4)3Cl] and pyromorphite [Pb5(PO4)3Cl] were performed up to 14.1 and 14.9 GPa, respectively, at 300 K, using in situ angle-dispersive X-ray diffraction and a diamond anvil cell. No phase transition of mimetite and pyromorphite was observed within the experimental pressure range. Fitting the P–V data under hydrostatic stress conditions with a third-order Birch–Murnaghan Equations of State (BM-EoS) we obtained: K 0=46(7) GPa, V 0=680(2) A3, and K 0′=15(4) for mimetite; K 0=44(5) GPa, V 0=636(1) A3, and K 0′=15(3) for pyromorphite. The axial compressibility was also calculated with a third-order ‘linearized’ BM-EoS. We obtained K 0a :K 0c =1:1.00 for mimetite, and K 0a :K 0c =1:1.28 for pyromorphite, indicating that mimetite and pyromorphite are elastically isotropic and slightly anisotropic, respectively. Comparing the previous equation of state data of vanadinite [Pb5(VO4)3Cl] with the current results of mimetite [Pb5(AsO4)3Cl] and pyromorphite...

In a hydrostatic pressure environment condition and in manual milling, respectively, investigations of PbWO4-III (P21 /n) have been performed by X-ray diffraction and Raman scattering techniques. Experiments found that PbWO4-III keeps its monoclinic structure under hydrostatic pressures with the sample’s anisotropic compressibility up to 14.6 GPa, but transforms to PbWO4-I (I41 /a) in a grinding process. The stability and variability of PbWO4-III depending on the strain states were also explored by first-principles calculations of elasticity. Calculations show PbWO4-III has an anisotropic compressibility and a ductile nature with increasing pressure up to 15 GPa.

BaWO4-II has been synthesized at 5 GPa and 610 degrees C. Its high pressure behavior was studied by in situ synchrotron X-ray diffraction measurements at room temperature up to 17 GPa. BaWO4-II retains its monoclinic structure. Bulk and axial moduli determined by fitting a third-order Birch-Murnaghan equation of state to lattice parameters are: K-0 = 86.2 +/- 1.9 GPa, K-0(a) = 56.0 +/- 0.9 GPa, K-0(b) = 85.3 +/- 2.4 GPa, and K-0(c) = 146.1 +/- 3.2 GPa with a fixed K' = 4. Analysis of axial compressible modulus shows that the a-axis is 2.61 times more compressible than the c-axis and 1.71 times more compressible than the b-axis. The beta angle decreases smoothly between room pressure and 17 GPa from 93.78 degrees to 90.90 degrees.

SUMMARY In situ measurements of elastic wave velocities and electrical conductivities in the three structural directions (normal to foliation Z, perpendicular to lineation in foliation Y and parallel to lineation X) for an amphibolite collected from southwestern margin of the Tarim Basin, northwest China, were carried out in the laboratory. The elastic wave velocity was measured with thecombinedtransmission–reflectionmethodatpressuresupto1.0GPa(atroomtemperature) and temperatures up to 700 ◦ C (at 1.0 GPa) and the electrical conductivity was measured with the impedance spectroscopy from 250 to 700 ◦ C at 1.0 GPa. The experimentally determined data included compressional (Vp) and shear wave velocities (Vs), velocity anisotropy (Av), intrinsic pressure and temperature derivatives of Vp and Vs, electrical conductivity (σ), electrical conductivity anisotropy (Aσ) and the parameters of the Arrhenius relationship. Elastic wave velocities increase in the structural directions Z, Y, X, with Vp of 6.63, 6.78 and 6.95 km s −1 and Vs of 3.75, 3.82 and 3.96 km s −1 for Z, Y and X, respectively, at pressure of 1.0 GPa. Elastic wave velocities increase linearly with pressure at room temperature and pressures between 0.25 and 1.0 GPa and decrease linearly with increasing temperature at 1.0 GPa. The pressure coefficients of the sample are in the range of 0.1883–0.2308 km s −1 GPa −1 for Vp and 0.1149–0.1678 km s −1 GPa −1 for Vs. The temperature coefficients are in the range of 2.09–2.35 × 10 −4 km s −1 GPa −1 for Vp and 1.28–1.68 × 10 −4 km s −1 GPa −1 for Vs .T he electrical conductivity increases with increasing temperature, consistent with the Arrhenius relationship. Activation energies for the three structural directions of the amphibolite are in the range of 0.71–0.75 eV. The amphibolite shows velocity anisotropy (4.15–4.86 per cent for Vp and 5.29–5.84 per cent for Vs at 0.25–1.0 GPa) and electrical conductivity anisotropy (11.1–25.2 per cent). Based on the regional crust model and geothermal gradient, velocity and electrical conductivity-depth profiles were calculated for the sample. These profiles were then compared with those derived from seismic reflection/refraction data and from electromagnetic data. Our results showed that the amphibolite sample has Vp and Vs in agreement with those of the middle and lower crust obtained from seismic reflection/refraction data, and σ in accord with that of the lower crust deduced from electromagnetic data. The lower crust of the electromagnetic crust model is roughly equivalent to the middle and lower crust layers of the seismic crust model. Therefore, it is suggest that the amphibolite may be one of the constituents of the present middle and lower crust in the Tarim Basin.

The high-pressure X-ray diffraction study of a natural arsenopyrite was investigated up to 28.2 GPa using in situ angle-dispersive X-ray diffraction and a diamond anvil cell at National Synchrotron Light Source, Brookhaven National Laboratory. The 16:3:1 methanol–ethanol–water mixture was used as a pressure-transmitting medium. Pressures were measured using the ruby-fluorescence method. No phase change has been observed up to 28.2 GPa. The isothermal equation of state (EOS) was determined. The values of K0, and K′0 refined with a third-order Birch–Murnaghan EOS are K0 = 123(9) GPa, and K′0 = 5.2(8). Furthermore, we confirm that the linear compressibilities (β) along a, b and c directions of arsenopyrite is elastically isotropic (βa = 6.82 × 10−4, βb = 6.17 × 10−4 and βc = 6.57 × 10−4 GPa−1).

The aim of this work is to quantitatively explore the texture evolution of amphibole aggregation and residual melt with pressure and temperature. The amphibole aggregation growth from a basaltic melt and the residual melt at high pressure (0.6–2.6[Formula: see text]GPa) and high temperature (860–970[Formula: see text]C) exhibit statistical self-similarity which made us consider studying such characteristic by fractal analysis. The bi-phase box counting method was applied for fractal analysis of each product to identify the fractal phase and the fractal dimension was estimated. In the experimental products, the residual melt is identified as the fractal and amphibole as the Euclidean except for one experiment. The results show that the residual melt can be quantified by the fractal dimension [Formula: see text] within the range of 1.782–1.848. The temperature has a significant effect on the morphology of amphibole and the fractal dimension of the residual melt. The higher the crystallization temperature is, the more regular the amphibole grains are. At lower temperature (from 860[Formula: see text]C to 915[Formula: see text]C), the fractal dimension of the residual melt decreased with the increasing crystallization temperature, but at higher temperature (970[Formula: see text]C), the fractal phase changed to amphibole and the fractal dimension of amphibole is 1.816. The pressure may be the dominant factor that controls the morphology of the mineral aggregation and the residual melt. The fractal dimension of melt decreased linearly with the increasing pressure and if the linear relationship between the fractal dimension and pressure can be further verified in the future, it can be used as a potential geological barometer.

We report geochronological, geochemical and isotopic data for the Mesozoic Shangshuiquan granite from the northern margin of the North China craton. The granite is highly fractionated, with SiO2 > 74%. Occurrence of annitic biotite, high contents of alkalis (K2O + Na2O), Rb, Y, Nb and heavy rare earth elements, high FeOt/MgO, low contents of CaO, Al2O3, Ba, and Sr, and large negative Eu anomalies, makes it indistinguishable from typical A-type granites. A mantle-derived origin for the rocks of the granite is not favored because their high initial 87Sr/86Sr (≥0.706) and low eNd (t) (

A pressure–volume–temperature data set has been obtained for natural chromium spinel, using synchrotron X-ray diffraction with a resistance heated diamond-anvil cell (RHDAC). The unit cell parameter of the chromium spinel was measured by energy dispersive X-ray diffraction up to pressures of 26.8 GPa and temperatures of 628 K. No phase change has been observed. The observed P–V–T data were fit to the high-temperature Birch-Murnaghan equation of state, with V 0 fixed at its experimental value, yields K 0 = 209 ± 9 GPa, (∂K/∂T)P = −0.056 ± 0.035 GPa K−1, and α0 = 7±1 × 10−5 K−1. The temperature derivative of the bulk modulus (∂K/∂T)P of chromium spinel is determined here for the first time. The obtained K 0 is slightly higher than the previous results of synthetic spinel. We suggest that Fe2+–Mg2+ substitution is responsible for the high bulk modulus of chromium spinel.

Melt glasses for seven types of rock ranging from acid to basic were prepared under 1.0 GPa on a multi-anvil pressure apparatus, YJ-3000 ton press. Densities and elastic properties of the melt glasses were compared with those described in previous studies. It was found that the glasses melted under 1.0 GPa were consistent in density with both naturally-occurring glassy rocks and artificially prepared glasses melted at ambient pressure. The densities of glasses are negatively correlated with the SiO2 contents and positively correlated with the (NgO+FeO) contents. The compressive velocity (Vp) of glass tends to increase with decreasing SiO2 contents and increasing (MgO+FeO) contents. The shear velocity (Vs) of glass tends to increase slightly with increasing SiO2 contents, which has little connection with the (MgO+FeO) contents. It was calculated from densities and velocities that the elastic moduli of glasses are negatively correlated with the SiO2 contents and positively correlated with the (MgO+FeO) contents.

At 1.0 GPa, compressional and shear wave velocities (vp and vs) of seven types of glass were measured as a function of temperature up to 900°C and 730°C, respectively. Experimental runs indicated that with elevating temperature under high pressure, the compression of glass is responsible for the decrease in travel time in sample and the glasses show little change in height during cooling process. When the temperatures are lower than the glass transition temperatures (Tg), it is fitted that the temperature derivatives of velocities of the glasses are between −0.2×10−3 km·s−1·°C−1 and −0.7×10−3 km·s−1·°C−1 for vp and almost −0.1×10−3 km·s−1·°C−1 for vs, respectively. At higher temperatures (T > Tg), vp of the glasses decrease quickly with temperature derivatives between −0.8×10−3 km·s−1·°C−1 and −3.6×10−3 km·s−1·°C−1. According to the change in temperature derivatives of vp, the glass transition temperatures are determined to be between 584°C and 654°C. Using the Voigt-Reuss-Hill (VRH) average method, it is calculated that the wave velocities of the lower crustal rocks decrease with increasing glass content. Because of this, we suggest that the low velocity layer in lower curst is a function of the glass contents in rocks, which results in a decrease in the wave velocity of rocks in lower crust.

Three Mesozoic plutons were intruded into the Archean granulite terrains in northern margin of the North China craton adjacent to the granulite xenolith-bearing Tertiary Hannuoba basalts. They are Triassic Guzuizi and Honghualiang granites and Early Cretaceous Zhuanzhilian diorite. Rocks of the three intrusions are characterized by high Sr (576–1216 ppm) and Na2O (⩾4.0%), low Y (⩽18 ppm) and heavy rare-earth elements (Yb