共查询到20条相似文献,搜索用时 15 毫秒
1.
Seismic source parameters of small to moderate sized intraplate earthquakes that occurred during 2002–2009 in the tectonic blocks of Kachchh Rift Basin (KRB) and the Saurashtra Horst (SH), in the stable continental region of western peninsular India, are studied through spectral analysis of shear waves. The data of aftershock sequence of the 2001 Bhuj earthquake (\(M_{w}\) 7.7) in the KRB and the 2007 Talala earthquake (\(M_{w}\) 5.0) in the SH are used for this study. In the SH, the seismic moment (\(M_{o})\), corner frequency \((f_{c})\), stress drop (\(\varDelta \sigma \)) and source radius (r) vary from \(7.8\times 10^{11}\) to \(4.0\times \)10\(^{16}\) N-m, 1.0–8.9 Hz, 4.8–10.2 MPa and 195–1480 m, respectively. While in the KRB, these parameters vary from \(M_{o} \sim 1.24 \,\times \, 10^{11}\) to \(4.1 \times 10^{16}\) N-m, \(f_{c }\sim \) 1.6 to 13.1 Hz, \(\varDelta \sigma \sim 0.06\) to 16.62 MPa and \(r \sim 100\) to 840 m. The kappa (K) value in the KRB (0.025–0.03) is slightly larger than that in the SH region (0.02), probably due to thick sedimentary layers. The estimated stress drops of earthquakes in the KRB are relatively higher than those in SH, due to large crustal stress concentration associated with mafic/ultramafic rocks at the hypocentral depths. The results also suggest that the stress drop value of intraplate earthquakes is larger than the interplate earthquakes. In addition, it is observed that the strike-slip events in the SH have lower stress drops, compared to the thrust and strike-slip events. 相似文献
2.
Petrography and mineralogy of four calc-alkaline granitoid plutons Agarpur, Sindurpur, Raghunathpur and Sarpahari located from west to east of northern Purulia of Chhotanagpur Gneissic Complex, eastern India, are investigated. The plutons, as a whole, are composed of varying proportions of Qtz–Pl–Kfs–Bt–Hbl±Px–Ttn–Mag–Ap–Zrn±Ep. The composition of biotite is consistent with those of calc-alkaline granitoids. Hornblende–plagioclase thermometry, aluminium-in-hornblende barometry and the assemblage sphene–magnetite–quartz were used to determine the P, T and \(f_{\mathrm{O}_2}\) during the crystallisation of the parent magmas in different plutons. The plutons are crystallised under varying pressures (6.2–2.4 kbar) and a wide range of temperatures (896–\(718{^{\circ }}\hbox {C}\)) from highly oxidised magmas (log \(f_{\mathrm{O}_2}\) \(-11.2\) to \(-15.4\) bar). The water content of the magma of different plutons varied from 5.0 to 6.5 wt%, consistent with the calc-alkaline nature of the magma. Calc-alkaline nature, high oxygen fugacity and high \(\hbox {H}_{2}\hbox {O}_{{\mathrm{melt}}}\) suggest that these plutons were emplaced in subduction zone environment. The depths of emplacement of these plutons seem to increase from west to east. Petrologic compositions of these granitoids continuously change from enderbite (opx-tonalite: Sarpahari) in the east to monzogranite (Raghunathpur) to syenogranite (Sindurpur) to alkali feldspar granite (Agarpur) in the west. The water contents of the parental magmas of different plutons also increase systematically from east to west. No substantial increase in the depth of emplacement is found in these plutons lying south and north of the major shear zone passing through the study area suggesting the strike-slip nature of the east–west shear zone. 相似文献
3.
Trend analysis of evapotranspiration over India: Observed from long-term satellite measurements 总被引:1,自引:0,他引:1
Sheshakumar Goroshi Rohit Pradhan Raghavendra P Singh K K Singh Jai Singh Parihar 《Journal of Earth System Science》2017,126(8):113
Owing to the lack of consistent spatial time series data on actual evapotranspiration (ET), very few studies have been conducted on the long-term trend and variability in ET at a national scale over the Indian subcontinent. The present study uses biome specific ET data derived from NOAA satellite’s advanced very high resolution radiometer to investigate the trends and variability in ET over India from 1983 to 2006. Trend analysis using the non-parametric Mann–Kendall test showed that the domain average ET decreased during the period at a rate of \(0.22\,\hbox {mm year}^{-1}\). A strong decreasing trend (\(m = -1.75\, \hbox {mm year}^{-1}\), \(F = 17.41\), \(P\) 0.01) was observed in forest regions. Seasonal analyses indicated a decreasing trend during southwest summer monsoon (\(m= -0.320\, \hbox {mm season}^{-1}\,\hbox {year}^{-1})\) and post-monsoon period (\(m= -0.188\, \hbox {mm season}^{-1 }\,\hbox {year}^{-1})\). In contrast, an increasing trend was observed during northeast winter monsoon (\(m = 0.156 \,\hbox {mm season}^{-1 }\,\hbox {year}^{-1})\) and pre-monsoon (\(m = 0.068\, \hbox {mm season}^{-1 }\,\hbox {year}^{-1})\) periods. Despite an overall net decline in the country, a considerable increase ( \(4 \,\hbox {mm year}^{-1}\)) was observed over arid and semi-arid regions. Grid level correlation with various climatic parameters exhibited a strong positive correlation (\(r \!>\!0.5\)) of ET with soil moisture and precipitation over semi-arid and arid regions, whereas a negative correlation (\(r\) \(-0.5\)) occurred with temperature and insolation in dry regions of western India. The results of this analysis are useful for understanding regional ET dynamics and its relationship with various climatic parameters over India. Future studies on the effects of ET changes on the hydrological cycle, carbon cycle, and energy partitioning are needed to account for the feedbacks to the climate. 相似文献
4.
N. V. Chukanov S. M. Aksenov R. K. Rastsvetaeva K. V. Van D. I. Belakovskiy I. V. Pekov V. V. Gurzhiy W. Schüller B. Ternes 《Geology of Ore Deposits》2015,57(8):721-731
A new mineral, mendigite (IMA no. 2014-007), isostructural with bustamite, has been found in the In den Dellen pumice quarry near Mendig, Laacher Lake area, Eifel Mountains, Rhineland-Palatinate (Rheinland-Pfalz), Germany. Associated minerals are sanidine, nosean, rhodonite, tephroite, magnetite, and a pyrochlore-group mineral. Mendigite occurs as clusters of long-prismatic crystals (up to 0.1 × 0.2 × 2.5 mm in size) in cavities within sanidinite. The color is dark brown with a brown streak. Perfect cleavage is parallel to (001). D calc = 3.56 g/cm3. The IR spectrum shows the absence of H2O and OH groups. Mendigite is biaxial (–), α = 1.722 (calc), β = 1.782(5), γ = 1.796(5), 2V meas = 50(10)°. The chemical composition (electron microprobe, mean of 4 point analyses, the Mn2+/Mn3+ ratio determined from structural data and charge-balance constraints) is as follows (wt %): 0.36 MgO, 10.78 CaO, 37.47 MnO, 2.91 Mn2O3, 4.42 Fe2O3, 1.08 Al2O3, 43.80 SiO2, total 100.82. The empirical formula is Mn2.00(Mn1.33Ca0.67) (Mn0.50 2+ Mn0.28 3+ Fe0.15 3+ Mg0.07)(Ca0.80 (Mn0.20 2+)(Si5.57 Fe0.27 3+ Al0.16O18). The idealized formula is Mn2Mn2MnCa(Si3O9)2. The crystal structure has been refined for a single crystal. Mendigite is triclinic, space group \(P\bar 1\); the unit-cell parameters are a = 7.0993(4), b = 7.6370(5), c = 7.7037(4) Å, α = 79.58(1)°, β = 62.62(1)°, γ = 76.47(1)°; V = 359.29(4) Å3, Z = 1. The strongest reflections on the X-ray powder diffraction pattern [d, Å (I, %) (hkl)] are: 3.72 (32) (020), 3.40 (20) (002, 021), 3.199 (25) (012), 3.000 (26), (\(01\bar 2\), \(1\bar 20\)), 2.885 (100) (221, \(2\bar 11\), \(1\bar 21\)), 2.691 (21) (222, \(2\bar 10\)), 2.397 (21) (\(02\bar 2\), \(21\bar 1\), 203, 031), 1.774 (37) (412, \(3\bar 21\)). The type specimen is deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow, registration number 4420/1. 相似文献
5.
A. I. Brusnitsyn 《Geochemistry International》2007,45(4):345-363
The paper summarizes experimental and calculation data on the effect of oxygen fugacity on the origin of mineral assemblages in Mn-bearing rocks and demonstrates the possibility of application of these data to the reconstruction of conditions under which metalliferous deposits were metamorphosed. A new variant of the T-log\(f_{O_2 } \) diagram is proposed for the Mn-Si-O system, which differs from previous ones by the location of the lines for the formation (decomposition) of braunite and tephroite. These two minerals are the most universal indicators of oxygen fugacity during the metamorphism of Mn-bearing deposits, because these minerals are widespread in nature and can be formed in diverse environments: braunite at high \(f_{O_2 } \) values in the pore solution, and tephroite at low \(f_{O_2 } \) values. The occurrence of Mn oxides and rhodonite (pyroxmangite) in a rock makes it possible to constrain the oxygen fugacity range. An original T-log\(f_{O_2 } \) diagram is constructed for the Ca-Mn-Si-O system. As follows from this diagram, a Ca admixture expands the stability field of rhodonite toward higher oxygen fugacity values. Johannsenite can be formed in these rocks at even higher \(f_{O_2 } \). The stability of both minerals is constrained in the region of low \(f_{CO_2 } \). The paper reports data on the Fe-Si-O and Mn-Fe-Si-O systems and discusses the possibility of applying the results of experiments in the Mn-Al-Si-O system to the estimation of conditions under which andalusite, spessartine, and galaxite can be formed in Mn-bearing rocks. Data on the mineralogy of numerous Mn deposits metamorphosed under various PTX parameters indicate that the origin of Mn-bearing mineral assemblages depends not so much on the temperature and pressure as on the oxygen fugacity, which is, in turn, controlled primarily by the composition of the pristine sediments (the presence or absence of organic matter in them) and host rocks and depends on the permeability of the rocks to oxygen, the P-T conditions, and the duration of the metamorphic processes. 相似文献
6.
Reza Ziaie Moayed Afshin Kordnaeij Hossein Mola-Abasi 《Geotechnical and Geological Engineering》2018,36(1):165-178
Pressuremeter modulus (\(E_{M}\)) and limit pressure (\(P_{L}\)) are used for the calculation of the settlement and bearing capacity of foundation respectively. As the determination of these parameters from pressuremeter test (PMT) is relatively time-consuming and expensive, various empirical correlations have been proposed to correlate the \(E_{M}\) and \(P_{L}\) to other soil parameters. For the existing equations are incapable of estimating these PMT parameters well, in present research group method of data handling type neural network is used to estimate the \(E_{M}\) and \(P_{L}\) of clayey soils. The \(E_{M}\) and \(P_{L}\) were modeled as a function of three variables including the moisture content (\(\omega\)), plasticity index and corrected SPT blow counts (\(N_{60}\)). A database containing 51 data sets have been used for training and testing of the models. The performances of proposed models are compared with those of existing empirical equations. The results demonstrate that appreciable improvement with respect to the other correlations has been achieved. At the end, sensitivity analysis of the obtained models has been performed to study the influence of input parameters on model outputs and shows that the \(N_{60}\) is the most influential parameter on the PMT parameters. 相似文献
7.
Paolo Ballirano 《Physics and Chemistry of Minerals》2011,38(7):531-541
Present work provides in-situ structural data at a fine temperature scale from RT to the melting point of nitratine, NaNO3. From the analysis of log e 33 versus log t plots, it is possible to prove that an univocal indication on the R \( \overline{3} \) c (low temperature, LT) → R \( \overline{3} \) m (high temperature, HT) transition mechanism cannot be obtained because of the relevant role played by the arbitrary assumptions required for defining the c 0 dependence from temperature of the HT phase. This is due to the occurrence of excess thermal expansion for the HT phase. A significantly better fit for an Ising-spin structural model over a non-Ising rigid-body one has been obtained for the LT phase. Moreover, the Ising model led to a smooth variation of the oxygen site x fractional coordinate throughout the transition. The structure of the HT polymorph has been successfully refined considering an oxygen site at x, 0, ½, with 50% occupancy. Such model was the only acceptable one from the crystal chemical point of view as the alternative model (oxygen site at x, y, z with 25% occupancy) led to unrealistically aplanar \( {\text{NO}}_{3}^{ - } \) groups. 相似文献
8.
Shabana Khan Jyoti L. Mishra Kuna-hui Elaine Lin Emma E. H. Doyle 《Natural Hazards》2017,85(3):1709-1722
We have studied the attenuation characteristics of eastern Himalaya and southern Tibet by using local earthquake data set that consists of 123 well-located events, recorded by the Himalayan Nepal Tibet Seismic Experiment operated during 2001–2003. We have used single backscattering model to calculate frequency-dependent values of coda Q (\(Q_\mathrm{c}\)). The estimation of \(Q_\mathrm{c}\) is made at central frequencies 2, 4, 8 and 12 Hz through five lapse time windows from 10 to 50 s starting at double the travel time of the S-wave. The observed \(Q_\mathrm{c}\) is found to be strongly frequency-dependent and follows a similar trend as observed in other tectonically active parts of the Himalaya. The trend of variation of \(Q_\mathrm{c}\) with lapse time and the corresponding apparent depths is also studied. Increase in \(Q_\mathrm{c}\) values with the lapse time suggests that the deeper part of the study region is less heterogeneous than the shallower part. The observed values of \(Q_0\) (\(Q_\mathrm{c}\) at 1 Hz) and frequency parameter n indicate that the medium beneath the study area is highly heterogeneous and tectonically very active. A regionalization of the estimated \(Q_0\) is carried out, and a contour map is prepared for the whole region. Some segments of Lesser Himalaya and Sub-Himalaya exhibit very low \(Q_0\) , while the whole Tethyan Himalaya and some parts of Greater Himalaya are characterized by low \(Q_0\) values. Our results are comparable with those obtained from tectonically active regions in the world. 相似文献
9.
D. A. Orsoev S. V. Kanakin Ya. A. Pakhomovsky Z. F. Ushchapovskaya L. Z. Reznitsky 《Geology of Ore Deposits》2016,58(7):579-585
The unnamed mineral CuFe2S4 has been found from sulfide Cu–Ni ores of the Lovnoozero deposit in the Kola Peninsula, Russia. It occurs in norite composed of orthopyroxene (bronzite), Ca-rich plagioclase (66% An), pargasite, and phlogopite. The last two minerals are replaced by talc, chlorite and carbonates. Monoclinic pyrrhotite, pentlandite, chalcopyrite, and pyrite are associated ore minerals. Phase CuFe2S4 is enclosed predominantly in chalcopyrite, probably replacing it, and occurs in later carbonate veinlets together with redeposited sulfides. It is light yellow with a brownish tint and metallic luster. The Mohs hardness is 5–5.5; VHN 654 ± 86 kgs/mm2. Density (calc.) = 4.524 g/cm3. The mineral is anisotropic, internal reflections are absent. Reflectance values (λ, nm R′ g and R′ p %) are: 440 30.3 29.5, 500 43.7 42.8, 560 50.9 49.6, 620 52.4 51.2, 640 52.6 51.4, 680 52.8 51.6, 700 52.7 51.4. CuFe2S4 is monoclinic, a = 6.260(4), b = 5.39(1), c = 13.19(1) Å, β = 94.88(7)°, V = 443(1) Å3, Z = 4. The strongest reflections in the powder diffraction pattern are [d, Å (I) (hkl)]: 4.150 (10) (012), 3.559 (4) (\(11\bar 2\)), 3.020 (4) (\(10\bar 4\)), 2.560 (3) (\(21\bar 2\)), 2.500 (3) (\(10\bar 5\)), 2.340 (3) (\(12\bar 2\)), 1.817 (3) (215), 1.489 (3) (402). The chemical composition is as follows, wt %: 20.44 Cu, 35.85 Fe, 0.65 Ni, 0.14 Co, 43.15 S, total is 100.23. The empirical formula calculated on the basis of 7 atoms is Cu0.969(Fe1.934Ni0.034Co0.007)1.975S4.056. According to its mode of occurrence, the mineral was formed as a result of low temperature processes involving metamorphic hydrothermal solutions. 相似文献
10.
The liquidus water content of a haplogranite melt at high pressure (P) and temperature (T) is important, because it is a key parameter for constraining the volume of granite that could be produced by melting of the deep crust. Previous estimates based on melting experiments at low P (≤0.5 GPa) show substantial scatter when extrapolated to deep crustal P and T (700–1000 °C, 0.6–1.5 GPa). To improve the high-P constraints on H2O concentration at the granite liquidus, we performed experiments in a piston–cylinder apparatus at 1.0 GPa using a range of haplogranite compositions in the albite (Ab: NaAlSi3O8)—orthoclase (Or: KAlSi3O8)—quartz (Qz: SiO2)—H2O system. We used equal weight fractions of the feldspar components and varied the Qz between 20 and 30 wt%. In each experiment, synthetic granitic composition glass + H2O was homogenized well above the liquidus T, and T was lowered by increments until quartz and alkali feldspar crystalized from the liquid. To establish reversed equilibrium, we crystallized the homogenized melt at the lower T and then raised T until we found that the crystalline phases were completely resorbed into the liquid. The reversed liquidus minimum temperatures at 3.0, 4.1, 5.8, 8.0, and 12.0 wt% H2O are 935–985, 875–900, 775–800, 725–775, and 650–675 °C, respectively. Quenched charges were analyzed by petrographic microscope, scanning electron microscope (SEM), X-ray diffraction (XRD), and electron microprobe analysis (EMPA). The equation for the reversed haplogranite liquidus minimum curve for Ab36.25Or36.25Qz27.5 (wt% basis) at 1.0 GPa is \(T = - 0.0995 w_{{{\text{H}}_{ 2} {\text{O}}}}^{ 3} + 5.0242w_{{{\text{H}}_{ 2} {\text{O}}}}^{ 2} - 88.183 w_{{{\text{H}}_{ 2} {\text{O}}}} + 1171.0\) for \(0 \le w_{{{\text{H}}_{ 2} {\text{O}}}} \le 17\) wt% and \(T\) is in °C. We present a revised \(P - T\) diagram of liquidus minimum H2O isopleths which integrates data from previous determinations of vapor-saturated melting and the lower pressure vapor-undersaturated melting studies conducted by other workers on the haplogranite system. For lower H2O (<5.8 wt%) and higher temperature, our results plot on the high end of the extrapolated water contents at liquidus minima when compared to the previous estimates. As a consequence, amounts of metaluminous granites that can be produced from lower crustal biotite–amphibole gneisses by dehydration melting are more restricted than previously thought. 相似文献
11.
The solubility of platinum and palladium in a silicate melt of the composition Di 55 An 35 Ab 10 was determined at 1200°C and 2 kbar pressure in the presence of H2O-H2 fluid at an oxygen fugacity ranging from the HM to WI buffer equilibria. The influence of sulfur on the solubility of platinum in fluid-bearing silicate melt was investigated at a sulfur fugacity controlled by the Pt-PtS equilibrium at 1200°C and a pressure defined in such a way that the \(f_{H_2 O} \) and \(f_{O_2 } \) values were identical to those of the experiments without sulfur. The experiments were conducted in a high pressure gas vessel with controlled hydrogen content in the fluid. Oxygen fugacity values above the NNO buffer were controlled by solid-phase buffer mixtures using the two-capsule technique. Under more reducing conditions, the contents of H2O and H2 were directly controlled by the argon to hydrogen ratio in a special chamber. The hydrogen fugacity varied from 5.2 × 10?2 bar (HM buffer) to 1230 bar (\(X_{H_2 } \) = 0.5). Pt and Pd contents were measured in quenched glass samples by neutron activation analysis. The results of these investigations showed that the solubility of Pt and Pd increases significantly in the presence of water compared with experiments in dry systems. The content of Pd within the whole range of redox conditions and that of Pt at an oxygen fugacity between the HM to MW buffer reactions are weakly dependent on \(f_{O_2 } \) and controlled mainly by water fugacity. This suggests that, in addition to oxide Pt and Pd species soluble at the ppb level in haplobasaltic melts, much more soluble (ppm level) hydroxide complexes of these metals are formed under fluid-excess conditions. Despite a decrease in water fugacity under reducing conditions, Pt solubility increases sharply near the MW buffer. It was shown by electron paramagnetic resonance spectrometry that, in contrast to dry melts, fluid-saturated silicate melts do not contain a pure metal phase (micronuggets). Therefore, the increase in Pt solubility under reducing conditions can be explained by the formation of Pt hydride complexes or Pt-fluid-silicate clusters. At a sulfur fugacity controlled by the Pt-PtS equilibrium, the solubility of Pt in iron-free silicate melts as a function of redox conditions is almost identical to that obtained in the experiments without sulfur at the same water and oxygen fugacity values. These observations also support Pt dissolution in iron-free silicate melts as hydroxide species. 相似文献
12.
The pressure–volume–temperature (P–V–T) relation of CaIrO3 post-perovskite (ppv) was measured at pressures and temperatures up to 8.6 GPa and 1,273 K, respectively, with energy-dispersive synchrotron X-ray diffraction using a DIA-type, cubic-anvil apparatus (SAM85). Unit-cell dimensions were derived from the Le Bail full profile refinement technique, and the results were fitted using the third-order Birth-Murnaghan equation of state. The derived bulk modulus \( K_{T0} \) at ambient pressure and temperature is 168.3 ± 7.1 GPa with a pressure derivative \( K_{T0}^{\prime } \) = 5.4 ± 0.7. All of the high temperature data, combined with previous experimental data, are fitted using the high-temperature Birch-Murnaghan equation of state, the thermal pressure approach, and the Mie-Grüneisen-Debye formalism. The refined thermoelastic parameters for CaIrO3 ppv are: temperature derivative of bulk modulus \( (\partial K_{T} /\partial T)_{P} \) = ?0.038 ± 0.011 GPa K?1, \( \alpha K_{T} \) = 0.0039 ± 0.0001 GPa K?1, \( \left( {\partial K_{T} /\partial T} \right)_{V} \) = ?0.012 ± 0.002 GPa K?1, and \( \left( {\partial^{2} P/\partial T^{2} } \right)_{V} \) = 1.9 ± 0.3 × 10?6 GPa2 K?2. Using the Mie-Grüneisen-Debye formalism, we obtain Grüneisen parameter \( \gamma_{0} \) = 0.92 ± 0.01 and its volume dependence q = 3.4 ± 0.6. The systematic variation of bulk moduli for several oxide post-perovskites can be described approximately by the relationship K T0 = 5406.0/V(molar) + 5.9 GPa. 相似文献
13.
Zhaolu Zhang Hui Kang Yunjun Yao Ayad M Fadhil Yuhu Zhang Kun Jia 《Journal of Earth System Science》2017,126(8):119
Evapotranspiration (ET) plays an important role in exchange of water budget and carbon cycles over the Inner Mongolia autonomous region of China (IMARC). However, the spatial and decadal variations in terrestrial ET and drought over the IMARC in the past was calculated by only using sparse meteorological point-based data which remain quite uncertain. In this study, by combining satellite and meteorology datasets, a satellite-based semi-empirical Penman ET (SEMI-PM) algorithm is used to estimate regional ET and evaporative wet index (EWI) calculated by the ratio of ET and potential ET (PET) over the IMARC. Validation result shows that the square of the correlation coefficients \((R^{2})\) for the four sites varies from 0.45 to 0.84 and the root-mean-square error (RMSE) is \(0.78\) mm. We found that the ET has decreased on an average of 4.8 mm per decade (\(p=0.10\)) over the entire IMARC during 1982–2009 and the EWI has decreased on an average of 1.1% per decade (\(p=0.08\)) during the study period. Importantly, the patterns of monthly EWI anomalies have a good spatial and temporal correlation with the Palmer Drought Severity Index (PDSI) anomalies from 1982 to 2009, indicating EWI can be used to monitor regional surface drought with high spatial resolution. In high-latitude ecosystems of northeast region of the IMARC, both air temperature \((T_{a})\) and incident solar radiation \((R_{s})\) are the most important parameters in determining ET. However, in semiarid and arid areas of the central and southwest regions of the IMARC, both relative humidity (RH) and normalized difference vegetation index (NDVI) are the most important factors controlling annual variation of ET. 相似文献
14.
In determining the physical and mechanical parameters of clay, it is sometimes necessary to determine them indirectly from other parameters since they cannot be measured directly from laboratory or field tests. In order to determine the effect of temperature on the behavior of clay, an indirect approach is used here by analyzing the changes of mass (\(\Delta m\)), density (\(\rho\)), porosity (\(\phi\)), P-wave velocity (\({v_p}\)), thermal conductivity (\(\lambda\)), specific heat capacity (c), resistivity (R) and uniaxial compressive strength (f) of clay from eastern China for a temperature range between 20 and 800 °C. The results indicate that temperature has a significant effect on these parameters. Comparisons between \(\Delta m\) and \(\rho\), \(\Delta m\) and \({v_p}\), \(\rho\) and \({v_p}\), \(\phi\) and \(\lambda\), \({v_p}\) and f, R and f show a linear change among these parameters,whereas the relationships among \(\Delta m\) and \(\phi\), \(\phi\) and \({v_p}\), \(\phi\) and R, \({v_p}\) and \(\lambda\), \(\phi\) and f are exponential. It is difficult to obtain these relationships by using regression analysis with high levels of accuracy. Further refinement is therefore required. 相似文献
15.
R G Rastogi P Janardhan H Chandra N B Trivedi Vidal Erick 《Journal of Earth System Science》2017,126(4):51
The effect of solar flare, sudden commencement of magnetic storm and of the disturbances ring current on the equatorial electrojet in the Eastern Brazil region, where the ground magnetic declination is as large as \(20^{^{\circ }}\hbox {W}\) is studied based on geomagnetic data with one minute resolution from Bacabal during November–December 1990. It is shown that the mean diurnal vector of the horizontal field was aligned along \(2{^{\circ }}\hbox {E}\) of north at Huancayo and \(30{^{\circ }}\hbox {W}\) of north at Bacabal during the month of December 1990. Number of solar flares that occurred on 30 December 1990 indicated the direction of solar flare related \(\Delta H\) vector to be aligned along \(5{^{\circ }}\hbox {E}\) of north at Huancayo and \(28{^{\circ }}\hbox {W}\) of north at Bacabal. This is expected as the solar flare effects are due to the enhanced conductivity in the ionosphere. The SC at 2230 UT on 26 November 1990 produced a positive impulse in \(\Delta X\) and negative impulse in \(\Delta Y\) at Bacabal with \(\Delta H\) vector aligned along \(27{^{\circ }}\hbox {W}\) of north. At Huancayo the \(\Delta H\) vector associated with SC is aligned along \(8{^{\circ }}\hbox {E}\) of north, few degrees east to the alignment of the diurnal vector of H. The magnetic storm that followed the SC had a minimum Dst index of –150 nT. The corresponding storm time disturbance in \(\Delta X\) at Huancayo as well as at Bacabal were about –250 nT but \(\Delta Y\) at Bacabal was about +70 nT and very small at Huancayo, that give the alignment of the H vector due to ring current about \(16{^{\circ }}\hbox {W}\) of north at Bacabal and almost along N–S at Huancayo. Thus alignment of the \(\Delta H\) vector due to ring current at Bacabal is \(14{^{\circ }}\hbox {E}\) of the mean direction of \(\Delta H\) vector during December 1990. This is consistent with the direction of ring current dependent on the dipole declination at the ring current altitude which is about \(5{^{\circ }}\hbox {W}\) of north over Bacabal and the deviation of declination due to the ring current during disturbed period given by the angle (\(\psi \)-D). 相似文献
16.
We present new partition coefficients for the REE, HFSE, Sn, In, Ga, Ba, Pt and Rh between clinopyroxene, olivine and basaltic melt as a function of crystal chemistry and melt composition at temperatures of 1190–1300 °C and 1-bar pressure. Two components, namely \(\mathrm {Al_2O_3}\) and \(\mathrm {Na_2O}\), were chosen to be investigated since they are known to affect the structure of silicate melts and especially clinopyroxene crystal chemistry. The amount of \(^{[4]}\mathrm{Al}\) in clinopyroxene will result in an increase of \(D_i^\mathrm{{cpx/melt}}\) even after applying a correction factor to account for the effect of melt polymerization. Moreover, the positive correlation between \(^{[4]}\mathrm{Al}\) and \(D_i^\mathrm{{cpx/melt}}\) is not restricted to the REE, but also applies for Sn, Ga, In, and Ba. The addition of up to 2.6 wt% \(\mathrm {Na_2O}\) to the silicate melt universally increases the \(D_i^\mathrm{{cpx/melt}}\) without any concomitant change in crystal chemistry or a significant effect in melt polymerization. This compositional effect is likely due to the ability of Na to break REE–Al complexes in the melt. Our results emphasize the importance of considering all variables that affect the behavior of trace elements in magmatic systems before applying the lattice strain model and derive meaningful results for the changes in the parameters of the crystallographic sites. 相似文献
17.
Middendorfite, a new mineral species, has been found in a hydrothermal assemblage in Hilairite hyperperalkaline pegmatite at the Kirovsky Mine, Mount Kukisvumchorr apatite deposit, Khibiny alkaline pluton, Kola Peninsula, Russia. Microcline, sodalite, cancrisilite, aegirine, calcite, natrolite, fluorite, narsarsukite, labuntsovite-Mn, mangan-neptunite, and donnayite are associated minerals. Middendorfite occurs as rhombshaped lamellar and tabular crystals up to 0.1 × 0.2 × 0.4 mm in size, which are combined in worm-and fanlike segregations up to 1 mm in size. The color is dark to bright orange, with a yellowish streak and vitreous luster. The mineral is transparent. The cleavage (001) is perfect, micalike; the fracture is scaly; flakes are flexible but not elastic. The Mohs hardness is 3 to 3.5. Density is 2.60 g/cm3 (meas.) and 2.65 g/cm3 (calc.). Middendorfite is biaxial (?), α = 1.534, β = 1.562, and γ = 1.563; 2V (meas.) = 10°. The mineral is pleochroic strongly from yellowish to colorless on X through brown on Y and to deep brown on Z. Optical orientation: X = c. The chemical composition (electron microprobe, H2O determined with Penfield method) is as follows (wt %): 4.55 Na2O, 10.16 K2O, 0.11 CaO, 0.18 MgO, 24.88 MnO, 0.68 FeO, 0.15 ZnO, 0.20 Al2O3, 50.87 SiO2, 0.17 TiO2, 0.23 F, 7.73 H2O; ?O=F2?0.10, total is 99.81. The empirical formula calculated on the basis of (Si,Al)12(O,OH,F)36 is K3.04(Na2.07Ca0.03)Σ2.10(Mn4.95Fe0.13Mg0.06Ti0.03Zn0.03)Σ5.20(Si11.94Al0.06)Σ12O27.57(OH)8.26F0.17 · 1.92H2O. The simplified formula is K3Na2Mn5Si12(O,OH)36 · 2H2O. Middenforite is monoclinic, space group: P21/m or P21. The unit cell dimensions are a = 12.55, b = 5.721, c = 26.86 Å; β = 114.04°, V = 1761 Å3, Z = 2. The strongest lines in the X-ray powder pattern [d, Å, (I)(hkl)] are: 12.28(100)(002), 4.31(81)(11\(\overline 4 \)), 3.555(62)(301, 212), 3.063(52)(008, 31\(\overline 6 \)), 2.840(90)(312, 021, 30\(\overline 9 \)), 2.634(88)(21\(\overline 9 \), 1.0.\(\overline 1 \)0, 12\(\overline 4 \)), 2.366(76)(22\(\overline 6 \), 3.1.\(\overline 1 \)0, 32\(\overline 3 \)), 2.109(54)(42–33, 42–44, 51\(\overline 9 \), 414), 1.669(64)(2.2.\(\overline 1 \)3, 3.2.\(\overline 1 \)3, 62\(\overline 3 \), 6.1.\(\overline 1 \)3), 1.614(56)(5.0.\(\overline 1 \)6, 137, 333, 71\(\overline 1 \)). The infrared spectrum is given. Middendorfite is a phyllosilicate related to bannisterite, parsenttensite, and the minerals of the ganophyllite and stilpnomelane groups. The new mineral is named in memory of A.F. von Middendorff (1815–1894), an outstanding scientist, who carried out the first mineralogical investigations in the Khibiny pluton. The type material of middenforite has been deposited at the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow. 相似文献
18.
Simple linear regression (SLR) models for rapid estimation of true subsurface resistivity from apparent resistivity measurements are developed and assessed in this study. The objective is to minimize the processing time and computer memory required to carry out inversion with conventional algorithms. The arrays considered are Wenner, Wenner–Schlumberger and dipole–dipole. The parameters investigated are apparent resistivity (\(\rho _a \)) and true resistivity (\(\rho _t\)) as independent and dependent variables, respectively. For the fact that subsurface resistivity is nonlinear, the datasets were first transformed into logarithmic scale to satisfy the basic regression assumptions. Three models, one each for the three array types, are thus developed based on simple linear relationships between the dependent and independent variables. The generated SLR coefficients were used to estimate \(\rho _t\) for different \(\rho _a\) datasets for validation. Accuracy of the models was assessed using coefficient of determination (\(R^{2})\), F-test, standard error (SE) and weighted mean absolute percentage error (wMAPE). The model calibration \(R^{2}\) and F-value are obtained as 0.75 and 2286, 0.63 and 1097, and 0.47 and 446 for the Wenner, Wenner–Schlumberger and dipole–dipole array models, respectively. The SE for calibration and validation are obtained as 0.12 and 0.13, 0.16 and 0.25, and 0.21 and 0.24 for the Wenner, Wenner–Schlumberger and dipole–dipole array models, respectively. Similarly, the wMAPE for calibration and validation are estimated as 3.27 and 3.49%, 3.88 and 5.72%, and 5.35 and 6.07% for the three array models, respectively. When compared with standard constraint least-squares (SCLS) inversion and Incomplete Gauss–Newton (IGN) algorithms, the SLR models were found to reduce about 80–96.5% of the processing time and memory space required to carry out the inversion with the SCLS algorithm. It is concluded that the SLR models can rapidly estimate \(\rho _t\) for the various arrays accurately. 相似文献
19.
A method has been developed to control ammonium fugacity, \(f_{{\text{NH}}_{3}}\), at elevated temperatures and pressures. The method uses an internal nitrogen buffer, the assemblage Cr + CrN, in conjunction with a traditional external hydrogen buffer. In this manner, all gas fugacities in the system N-O-H can be calculated.The Cr + CrN buffer has been applied to study equilibria between buddingtonite (ammonium feldspar), ammonium muscovite, sillimanite, and quartz at a constant gas pressure of 2,000 bars. Two of the five relevant reactions were measured experimentally; from these data, it is possible to calculate isothermal sections at 500, 600, and 700° C.Below 600° C, ammonium muscovite is stable even at extremely low levels of \(f_{{\text{NH}}_{3}}\), while buddingtonite requires \(f_{{\text{NH}}_{3}}\;\geqq\;10^4\) bars. Release of NH3 during progressive metamorphism can be achieved by three processes: thermal decomposition, dehydration, and cation exchange. Within the crust, \(f_{{\text{NH}}_{3}}\) predominates over \(f_{{\text{N}}_{2}}\) by several orders of magnitude; but on the surface, nitrogen released as NH3 by metamorphism will be oxidized to N2. Biological materials provide important intermediate storage for nitrogen compounds during the nitrogen cycle. 相似文献