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1.
A worldwide data set of 1,085 samples containing organic matter of the type II/III kerogen from Carboniferous to Cenozoic was used to analyse the evolution of the hydrogen index (HI), quality index (QI), and bitumen index (BI) with increasing thermal maturity. The HImax, QImax and BImax lines were defined, based on statistical analysis and cross-plots of HI, QI and BI versus the vitrinite reflectance (%Ro) and T max (°C). The constructed HI, QI and BI bands were broad at low maturities and gradually narrowed with increasing thermal maturity. The petroleum generation potential is completely exhausted at a vitrinite reflectance of 2.0–2.2 % and T max of 510–520 °C. An increase in HI and QI suggests extra petroleum potential related to changes in the structure of the organic material. A decline in BI signifies the start of the oil window and occurs within the vitrinite reflectance range 0.75–1.05 % and T max of 440–455 °C. Furthermore, petroleum potential can be divided into four different parts based on the cross-plot of HI versus %Ro. The area with the highest petroleum potential is located in “Samples and methods” with %Ro = 0.6–1.0 %, and HI > 100. Oil generation potential is rapidly exhausted at “Results and discussion” with %Ro > 1.0 %. This result is in accordance with the regression curve of HI and QI with %Ro based on 80 samples with %Ro = 1.02–3.43 %. The exponential equation of regression can thus be achieved: HI = 994.81e?1.69Ro and QI = 1,646.2e?2.003Ro (R 2 = 0.72). The worldwide organic material data set defines two range of oil window represented by the upper and lower limits of the BI band: %Ro 0.75–1.95 %, T max 440–525 °C, and %Ro 1.05–1.25 %, T max 455–465 °C, respectively.  相似文献   

2.
Two daily sets of monitoring data of the Galactic X-ray binary SS 433 (V1343 Aql) obtained on the RATAN-600 radio telescope (117 days in 1997 and 120 days in 1999) show variations in its quiescent radio emission with a period of 6.05±0.1 days at six frequencies from 0.96 to 22 GHz. This 10–15% modulation in the quiescent radio light curves differs significantly from the well-known 6.28-day periodicity in the emission of moving spectral features and in optical photometric data, which are related to nodding motions of the jets and accretion-disk wobble. This period coincides almost exactly with the theoretical value for the harmonic f=2(I o+I p), related to the orbital (T o=13.08 days) and precessional (T p=162.4 days) periods for slaved accretion-disk models. The 6.06-day period corresponds to the combined frequency. It is proved that the modulation of the radio flux of SS 433 may be associated with relativistic boosting of the jet emission due to periodic variation of the orientation of the jets, which are nodding with a period of six days. The synchrotron emission of the two jets contributes to the quiescent radio flux of SS 433, and the six-day harmonic has the same radio spectrum as the quiescent radio flux: S v ～v ?0.6.  相似文献   

3.
The elastic moduli of single-crystal MgF2 have been determined by the ultrasonic pulse superposition technique as a function of temperature from T=298?650° K. These new data are consistent with those obtained by other ultrasonic pulse techniques at and below room temperature and agree favourably with polycrystalline data above room temperature. The elastic moduli (c) are represented by quadratic functions in T over the experimental temperature range with the curvature in the same sense for all the moduli. For the rutile-structure fluorides and oxides, evaluation of the temperature derivatives of the elastic moduli at constant volume indicates that the dominant temperature effect is extrinsic for (?K S /?T) P and intrinsic for (?μ/?T) P , where K S and μ are the isotropic bulk and shear moduli, respectively. There appears to be no simple relationship between (?c/?T) P and crystallographic parameters for the rutile structure, and |(?c/?T) P | for the fluorides is in general very much lower than the corresponding |(?c/?T) P | for the oxides. For the pair of compounds MgF2-TiO2, there is no evident analogue relationship for high-temperature elastic properties.  相似文献   

4.
Thermal equations of state have been derived for polymorphic forms of SiO2 and values of \(\mathop \smallint \limits_0^P\) V T dP have been tabulated. Available experimental data on the phase equilibria at high pressures and temperatures have been used with these equations to calculate the standard thermodynamic functions for the α-quartz-coesite and coesite-stishovite transformations. A study of sensitivity of calculated thermodynamical properties to uncertainties of phase equilibria data, initial data for elastic constants and equations of state has been carried out. The discrepancies between standard thermodynamic properties of these transformations calculated from phase equilibria data and solution calorimetry data still persist.  相似文献   

5.
Solubilities of silver chloride in aqueous hydrochloric acid solutions have been determined from 100 up to 350°C. From these measurements, the ionisation constant of HC1 has been evaluated up to 225°C. Evidence is presented to show that a protonated silver species, HAgCl20, exists at 275°C and above. Available experimental data up to 200°C have been firted to Pitzer's equation to generate an algorithm to calculate stoichiometric activity and osmotic coefficients of HCl up to 350°C and concentrations up to at least 3.0 m. Using the present results and those of Wrightet al. (1961), Pearsonet al. (1963) and Lukashowet al. (1976), the dissociation constant (Kd) of HCl as a function of temperature is described by the equation log10K = 2136.898 + 1.020349T−4.5045 × 10−4T2−50396.40/T−901.770 10g10T (Tin °K) which is valid in the range 25–350°C. Calculated enthalpy (ΔH0), entropy (ΔS0) and heat capacity change (ΔCp0) functions for HCl dissociation have been rationalized in terms of changing solute and solvent characteristics as temperature is raised.  相似文献   

6.
Thermochronologic data are typically interpreted as point- or path-wise constraints on monotonic cooling histories. This is at least partly because allowing for the possibility of nonmonotonic thermal histories both precludes straightfoward use of closure temperature (Tc) concepts and introduces ambiguities in modeling continuous time-temperature paths from multiple thermochronometers or closure profile, multi-domain, or fission-track length data. However, the monotonic cooling assumption severely limits the ability to elucidate reheating episodes with potentially important geologic significance. Here I show that in some cases multiple thermochronometers with contrasting kinetic properties can be used to both diagnose reheating events and constrain their duration and temperature. Thermochronometric systems with varying activation energies display “kinetic crossovers,” whereby relative diffusivities are reversed at certain temperatures. For reheating events of certain durations and temperatures, this results in “inverted” ages, whereby systems with higher nominal Tcs have younger ages than systems with lower Tcs. However, even if reheating does not cause age inversion, in cases where two systems are partially reset and constraints on the timing of a reheating event are available, the relative fractional resetting extents can be inverted to estimate a square-pulse equivalent duration and temperature of the reheating event. Here I outline this approach for diagnosing nonmonotonic thermal histories and for deducing features of reheating events from thermochronometric data, and review several examples from previously published data that illustrate its use and potential in a range of applications.  相似文献   

7.
From the connnection between the homologous temperature T/Tm and the viscosity a stabilization effect at viscosities of about 1023 poise is achieved for T/Tm = 0.6–0.7. This most probably is the steady-state temperature in the upper mantles of terrestrial planets of similar composition and should be a function of pressure only. Solid-state convection in the (larger) planets is connected with deviations of temperature and viscosity from their steady-state values. Viscosity values are obtained from the uplift data of deglaciated shield areas and from the temperature and strain-rate values of oceanic plate movements. Differences in the homologous temperature of 0.1 between both regions result in differences in viscosity by two orders of magnitude, assuming the crystal size of the material to be equal. The lower viscosity values for oceanic regions may explain the absence of seismicity and the generally faster spreading rates of purely oceanic plates. From the analysis of the uplift data two creep laws are indicated. Also the temperature (T = 0.7 Tm) and the crystal size in the upper mantle (0.1–1 cm) has been obtained from these data. Diffusion creep with a linear relationship between stress and strain rate seems to be important for small stresses, below one bar. This kind of creep apparently exists during the final stage of isostatic uplift and in most parts of the oceanic asthenospheric flow. Dislocation or power-law creep prefers larger stresses like those found in regions of fast uplift, in descending oceanic plates, active plate marginsand perhaps in the depth range of reverse flow.  相似文献   

8.
We use a lattice vibrational technique to derive thermophysical and thermochemical properties and phase equilibria in the system MgO-SiO2 at pressures and temperatures relevant to Earth’s mantle. The technique is based on an extension of Kieffer’s model to incorporate details of the phonon spectrum, and it includes treatment of intrinsic anharmonicity. We use a least squares inversion technique applied to available experimental data, and show that it results in an accurate representation of thermodynamic properties and sound wave velocities of high-pressure phases in the system MgSiO3. The vibrational method has been validated against laboratory experimental data in the temperature range between 0 and 2500 K and at pressures between 1 bar and 30 GPa. The technique results in a phase diagram consistent with the majority of thermophysical and thermochemical data. It is shown that intrinsic anharmonicity affects significantly slopes and positions of the phase boundaries. Our analysis indicates inconsistencies in a number of data sets of thermophysical properties for stishovite, majorite and ortho-enstatite necessitating new measurements. For akimotoite elasticity data at high-pressure and high-temperature conditions and 1 bar heat capacity measurements are needed. For stishovite elasticity measurements are necessary to reconcile elasticity data with V-P-T measurements. Additionally V-P-T measurements at pressures higher than 10 GPa are needed, which should be reconciled with V-P-T data at lower pressures. Raman and infrared spectroscopic data are necessary for both clino-enstatite and majorite. Additionally structural data are needed to resolve the discrepancy between values for the degree of disorder in majorite. Volume expansion data for ortho-enstatite are needed and effects causing differences in measured volume expansion should be elucidated.  相似文献   

9.
Based on the MAGSAT magnetic anomaly fields over Europe and the adjacent areas spherical cap models have been derived. The method of spherical cap harmonic analysis, due to Haines (1985), has been applied for the modelling of the MAGSAT magnetic anomalies. The data set used in the analysis included the 1 ° × 1 ° gridded values of the MAGSAT anomaly fields between latitudes ϑ = 6 ° to 60 °N and longitudes λ = 19 °W to 70 °E. The pole of the cap is at ϑ = 33 °N and λ = 26 °E and its half-angle is 40 ° . The maximum index (Km) of the model is 18 and the total number of model coefficients is 361. A minimum wavelength corresponding to this index at the Earth's surface is ~ 1000 km. The RMS deviations between the calculated and observed values are ~ 4 nT for δX, ~ 3 nT for ΔY and 3,5 nT for ΔZ respectively. The spherical cap harmonic model was used for the construction of magnetic anomaly maps for all components and at different altitudes.  相似文献   

10.
We discuss approaches to mapping lateral apparent conductivity variations at different periods from magnetic observatory data using multipoint transfer operators as nonlocal functions of the EM response. The multipoint operators provide correlation of three magnetic field components recorded at all observatories. The inversion procedure was applied to Sq observatory data for 1964–68 and records of 30 magnetic storms for 1957–2001. To obtain lateral conductivity patterns, data on diurnal Sq variations and global magnetic storms were processed with the spherical harmonic analysis. The same data were used to estimate the coefficients of first harmonics in the SH series of diurnal lateral variations of Earth's apparent conductivity.  相似文献   

11.
The distribution of interatomic distances in amorphous NaAlSi3O8 has been determined at 805°C by X-ray radial distribution analysis to investigate structural differences between the glass (T < 763°C) and the supercooled liquid (763°C < T < 1118°C). Except for slight differences attributable to thermal expansion, no significant changes were observed. The sample crystallized during the course of the experiment, but at least one crystal-free data set was obtained. The transition from the inferred six-membered ring structure of the supercooled liquid to the four-membered ring structure of the crystal was clearly visible in radial distribution function (RDF's) determined before and after crystallization.RDF's were also determined at 25°C for two NaAlSi3O8 glasses with different histories. The first was derived from a melt that had been cooled slowly from 1600 to 32°C above the melting point (Tf = 1118°C) to detect possible repolymerization to a more ‘crystal-like’ structure as the melt approached Tf. The second glass was prepared by holding a single crystal of Amelia albite at 50°C above Tf to see if the crystalline four-membered ring structure was preserved in melts at temperatures just above the liquidus. No significant differences were observed between these two RDF's and one obtained from a glass quenched from 1800°C. These results suggest that in addition to the destruction of formation of a periodic structure, melting and crystallization in NaAlSi3O8 also involves a repolymerization of tetrahedra. This would explain the observed kinetic barrier to melting and crystallization in the anhydrous system and the catalytic effect of small amounts of water or alkali oxide.  相似文献   

12.
This contribution proposes a number of methodological refinements for accounting for ejection of energetic particles, most particularly in the case of long alpha-particle stopping distance effects in (U-Th-Sm)/He thermochronometry. Recent stopping-distance estimates for minerals commonly used for thermochronometry are up to 1.5 μm shorter than previously thought, which directly affects the magnitude of the ejection correction parameter FT. The revision in stopping distances necessitates re-fitting the empirical polynomials that have been used to calculate FT corrections for various crystal forms. Reformulation and re-parameterization of these polynomials enables them to account for present and any future change in stopping distances without needing to be recalibrated. The library of shapes described with these polynomials to accommodate habits is expanded for all crystal systems and also ellipsoids, thus covering all minerals currently used and under development for (U-Th-Sm)/He thermochronometry. In addition, the inaccuracy caused by characterizing a set of alpha particles from a decay chain with a single mean stopping distance is examined, and a simple method for compensation is recommended. A new method of using FT parameters to calculate corrected ages by applying them to parents instead of daughters or age is presented, which maximizes accuracy for old specimens such as meteorites. Altogether, the refinements proposed will affect (U-Th-Sm)/He ages by ∼1-5%, depending on size and age. Finally, the concept of an FT-equivalent sphere is introduced as a sphere with the same effective FT value as a given mineral grain. Testing indicates that the FT-equivalent sphere is of comparable or superior accuracy to a sphere of the same surface to volume ratio for diffusion modeling. This finding greatly facilitates utilization of (U-Th-Sm)/He data from standard data tables for forward and inverse modeling.  相似文献   

13.
P-V-T equations of state for the γ phase of Mg2SiO4 have been fitted to unit cell volumes measured under simultaneous high pressure (up 30 GPa) and high temperature (up to 700 K) conditions. The measurements were conducted in an externally heated diamond anvil cell using synchrotron x-ray diffraction. Neon was used as a pressure medium to provide a more hydrostatic pressure environment. The P-V-T data include 300 K-isothermal compression to 30 GPa, 700 K-compression to 25 GPa and some additional data in P-T space in the region 15 to 30 GPa and 300 to 700 K. The isothermal bulk modulus and its pressure derivative, determined from the isothermal compression data, are 182(3) GPa and 4.2(0.3) at T=300 K, and 171(4) GPa and 4.4(0.5) at T=700 K. Fitting all the P-V-T data to a high-temperature Murnaghan equation of state yields: K TO=182(3.0) GPa, K TO=4.0(0.3), ?K T /?T)0=?2.7(0.5)×10?2 GPa/K and (?2 K T /?P?T)0=5.5(5.2)×10?4/K at the ambient condition.  相似文献   

14.
Cooling and decompression experiments have been carried out on trachytic melts in order to investigate crystallization kinetics of alkali feldspar, the effect of the degree of undercooling (ΔT = T liquidus ? T experimental) and time on nucleation and crystal growth process. This experimental work gives us new data about crystallization kinetics of trachytic melts, and it that will be useful to better understand the natural system of Campi Flegrei volcanoes. Experiments have been conducted using cold seal pressure vessel apparatus, at pressure between 30 and 200 MPa, temperature between 750 and 855 °C, time between 7,200 and 57,600 s and redox condition close to the NNO +0.8 buffer. These conditions are ideal to reproducing pre- and syn-eruptive conditions of the Campi Flegrei volcanoes, where the “conditions” pertain to the complete range of pressures, temperatures and time at which the experiments were performed. Alkali feldspar is the main phase present in this trachyte, and its abundance can strongly vary with small changes in pressure, temperature and water content in the melt, implying appreciable variations in the textures and in the crystallization kinetics. The obtained results show that crystallization kinetics are strictly related to ΔT, time, final pressure, superheating (?ΔT) and water content in the melt. ΔT is the driving force of the crystallization, and it has a strong influence on nucleation and growth processes. In fact, the growth process dominates crystallization at small ΔT, whereas the nucleation dominates crystallization at large ΔT. Time also is an important variable during crystallization process, because long experiment durations involve more nucleation events of alkali feldspar than short experiment durations. This is an important aspect to understand magma evolution in the magma chamber and in the conduit, which in turn has strong effects on magma rheology.  相似文献   

15.
An outline for a metamorphic grid involving a greenschist facies assemblage is presented in Watts (1973). This grid is derived from a theoretical determination of all possible P-T dependent (solid-solid) reactions and invariant points as well as those in which a fluid, containing CO2, H2O and other unspecified components, takes part. The thermodynamic data in Watts (1973) were accidentally calculated at 425° K and not at 425° C. Since 425° K is an unreasonably low temperature for greenschist facies equilibria, these data have been recalculated at 700° K (427° C) and a new topology of fluid-absent (solid-solid) reactions and invariant points in P-T space results, since the slopes of such reactions change under conditions at the higher temperature. The slopes of the fluid-bearing reactions are independent of P, T and remain unchanged. However, for each different P-T grid of solid-solid reactions, a new set of chemographic arrangements is valid for the fluidbearing invariant points. A set of μH2O-μCO2 diagrams consistent with, and dependent on the new P-T grid is presented.  相似文献   

16.
The influence of Al/Si disorder in the anorthite tetrahedral framework upon the I \(\bar 1\) -P \(\bar 1\) displacive transition of that framework has been investigted at high-temperature by powder X-ray diffraction. The temperature-dependence of the order parameter in a heat-treated (disordered) anorthite and a Ca-rich plagioclase has been determined from spontaneous strain measurements. Both samples show appreciable disorder, with Q od = 0.88 in both cases. In each, the critical exponent β appears to be intermediate between values for classical tricritical (1/4) and second-order (1/2) phase transitions. This critical behaviour is consistent with a Landau potential in which the coefficient of the quartic term is positive but smaller than the coefficient of the sixth order term, corresponding to a second-order phase transition close to a tricritical point. There does not appear to be any defect strain tail near T c and inhomogeneities in Q od appear to be on rather a short length scale in these samples. The role of changing Q od appears to be more important than that of changing composition (albite component). The data are interpreted using a model of a homogeneous field due to changing Q od which renormalizes the transition temperature, T c * , and the fourth order coefficient, B eff, in the Landau expansion. The results are consistent with classical Landau behaviour, and demonstrate the care which must be taken in interpreting apparently non-classical critical exponents for phase transitions close to a tricritical point.  相似文献   

17.
This paper gives an analytical overview of the experimental data obtained by different authors at high P and T in the model system MgO–Al2O3–SiO2–Cr2O3 (MASCr). A set of four simple polynomial equations is proposed for the temperature and pressure dependence of chromium content in garnet and spinel in the assemblage Gar + Opx + Es and Gar + Fo + Opx + Sp.From the first equation, one can estimate the minimum pressure at a given temperature which is required for the formation of peridotite garnets of uncertain paragenesis with a known knorringite content. A combination of the second and third equations helps estimate P and T from the chromium content of garnet and spinel from assemblages containing both minerals. If the spinel composition is unknown, but there is reason to assign garnet to a spinel-bearing paragenesis, the fourth equation is applicable for estimating pressure at given temperature.Originally, the proposed garnet–spinel geothermobarometer was developed for a harzburgite paragenesis. However, it is applicable to garnets with CaO/Cr2O3 < 0.903 (including lherzolitic ones), that is, those within the Pyr–Kn–Uv triangle of the reciprocal quaternary diagram Pyr–Cros–Uv–Kn.Using the above equations and an empirical PCG geobarometer (Grütter et al., 2006), comparative geothermobarometric estimates were obtained for a set of garnet and garnet–spinel inclusions in diamonds and intergrowths with diamond, as well as garnet inclusions in spinel. If garnet has CaO/Cr2O3 = 0.35–0.40, the results are in good accord. For Cr-richest and Ca-poorest garnets, the PCG barometer shows pressures 10–15% higher compared with our estimates.  相似文献   

18.
Based on the fluid phase equilibrium of the C-O-H system, the compositions of various fluid phases under high temperatures and pressures have been calculated in terms of the available thermodynamic data and newP-V-T data and on the assumption ofP T= ΣPi in this paper. The results indicate that in this system there are 5 major fluid phases in different proportions at variousT andP. CH4 is the dominant phase (about 70%) under relatively lowerT andP. Its proportion obviously decreases with increasingT, P andfo2. The results provide sufficient theoretical grounds for discussing the possibility of CH4 formation and the physical-chemical conditions of its stable occurrence and proportion in the geological environment.  相似文献   

19.
A new expression for the heat capacity of solids is proposed: a) for fitting the measured low-temperature heat capacity data on crystals, and b) for estimating heat capacity at high temperatures without violating the limit set by Petit and Dulong (1819). Cp = 3Rn(1 + k1T−1 + k2T−2 + k3T−3) + (A + BT) + C'p where R and n are the gas constant and the number of atoms in the chemical formulae, respectively. A and B are calculated from thermal expansion coefficient and isothermal bulk modulus data. The ki's are determined by fitting the measured low-temperature heat capacity data. C'p is the departures from the 3Rn limit for some substances due to cation disordering, anharmonicity and electronic contributions.The five constants in the proposed equation were determined for six minerals for which the physical properties have been well studied. The errors possibly resulting from experimental measurements or extrapolations of the thermal expansion coefficient and bulk modulus were carefully examined.  相似文献   

20.
An amplitude-frequency analysis of a few-parameter model for intraday oscillations of the Earth’s pole induced by gravitational-tidal torques exerted by the Sun and the Moon is presented. The characteristic features of the intraday oscillations in the polar coordinates are found using the dynamical Euler-Liouville equations, taking into account irregular perturbations. The modeling results for the polar motion are compared with high-accuracy VLBI observations over short time intervals. An amplitude-frequency analysis of the polar oscillations and the second zonal harmonic c 20 of the geopotential is presented.  相似文献   

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