Expanding energy as a function of volume in a Taylor series and taking the Padé approximant, different equations of state have been obtained, which are first tested with Born-Mayer and logarithmic model solids. These equations of state are applied to compute pressure, compressibility and the Moelwyn-Hughes parameter as functions of volume for NaCl, AgCl and CsCl crystals. The results agree fairly well with the observed data. 相似文献
Earlier, under certain simplifying assumptions, on the basis of the General Theory of Relativity, it has been concluded by many authors that when the radius of a gravitationally collapsing spherical object of massM reaches the critical value of the Scharzschild radiusRs=2GM/c2, then, in a co-moving frame, the object collapses catastrophically to a point. However, in drawing this conclusion due consideration has not been given to the nuclear forces between the nucleons. In particular, the very strong ‘hard-core’ repulsive interaction between the nucleons which has the range ~0.4×10?13 cm has been totally ignored. On taking into account this ‘hard-core’ repulsive interaction, it is found that no spherical object of massM g can collapse to a volume of radius smaller thanRmin=(1.68×10?6)M1/3 cm or to a density larger than ρmax=5.0 × 1016 g cm?3. It has also been pointed out that objects of mass smaller thanMc~1.21×1033 g can not cross the Schwarzschild barrier and gravitationally collapse. The only course left to the objects of mass less thanMcis to reach the equilibrium as either a white dwarf or a neutron star. 相似文献
Distinctly different groundmass mineralogy characterise the hypabyssal facies, Mesoproterozoic diamondiferous P3 and P4 intrusions from the Wajrakarur Kimberlite Field, southern India. P3 is an archetypal kimberlite with macrocrysts of olivine and phlogopite set in a groundmass dominated by phlogopite and monticellite with subordinate amounts of serpentine, spinel, perovskite, apatite, calcite and rare baddeleyite. P4 contains mega- and macrocrysts of olivine set in a groundmass dominated by clinopyroxene and phlogopite with subordinate amounts of serpentine, spinel, perovskite, apatite, and occasional gittinsite, and is mineralogically interpreted as an olivine lamproite. Three distinct populations of olivine, phlogopite and clinopyroxene are recognized based on their microtextural and compositional characteristics. The first population includes glimmerite and phlogopite–clinopyroxene nodules, and Mg-rich olivine macrocrysts (Fo 90–93) which are interpreted to be derived from disaggregated mantle xenoliths. The second population comprises macrocrysts of phlogopite and Fe-rich olivine (Fo 81–89) from P3, megacrysts and macrocrysts of Fe-rich olivine (Fo 85–87) from P4 and a rare olivine–clinopyroxene nodule from P4 which are suggested to have a genetic link with the precursor melt of the respective intrusions. The third population represents clearly magmatic minerals such as euhedral phenocrysts of Fe-rich olivine (Fo 85–90) crystallised at mantle depths, and olivine overgrowth rims formed contemporaneously with groundmass minerals at crustal levels. Close spatial association and contemporaneous emplacement of P3 kimberlite and P4 lamproite is explained by a unifying petrogenetic model which involves the interaction of a silica-poor carbonatite melt with differently metasomatised wall rocks in the lithospheric mantle. It is proposed that the metasomatised wall rock for lamproite contained abundant MARID-type and phlogopite-rich metasomatic veins, while that for kimberlite was relatively refractory in nature.
Ground and airborne magnetic data are severely disturbed due to random susceptibility variations in Deccan flood basalts. However, Magnetic Satellite (MAGSAT) data over the Deccan flood basaltic region of the Indian subcontinent exhibit filtering of surficial noise. Three passes over Deccan traps show a low at about 20°N latitude and a high at about 23°N latitude. Spectral analysis of these passes and an available 2-D MAGSAT vertical intensity map indicate a deep (40±4 km) magnetic interface. It is interesting to note that the determination of Curie-depth from MAGSAT matches and confirms the geothermal data model. The estimates correspond to the Moho depth derived from gravity and deep seismic sounding studies. The study suggests a continental shield-like geothermal gradient of about 14°C/km below the area. 相似文献
Normal faults on mesoscopic scale are observed in the Panjal Thrust Zone in the Dalhousie area of western Htmachal. The boundary
between the southern margin of the Higher Himalaya Crystalline (HHC) of Zanskar and the Chamba syncline sequence is also described
as a normal fault, referred to as Bhadarwah Normal Fault in the Bhadarwah area of Doda district on the basis of field mapping
and shear sense criteria using S-C fabric and porphyroblast rotation. The occurrence of these normal faults suggests that
the extensional tectonic regime was not restricted only to the Zanskar shear zone area but that it also occurs south of the
Higher Himalayan range. This suggests NE-directed subhorizontal extension and exhumation of deeper level rocks of Higher Himalaya
Crystallines. 相似文献
Snow avalanche studies require different snow-meteorological parameters for avalanche forecasting. Snow surface temperature
is one of the major parameters, which is responsible for the evolution of snow pack characteristics. In the present paper,
the snow surface temperature was estimated using TERRA satellite based — Moderate resolution imaging spectroradiometer (MODIS)
sensor for NW-Himalayas. Ground data observed by automatic weather stations (AWS) was used to calibrate the brightness temperature
obtained by MODIS thermal bands data into the actual snow surface temperature data through regression analysis. A split window
technique has been implemented for the estimation of snow surface temperature. The multi-date satellite derived snow surface
temperature was validated with ground data of winter 2004–05 and 2005–06 collected at various observation stations located
in different ranges of NW-Himalaya. Good correlations were observed for Upper Himalaya (0.98, 0.98), Middle Himalaya (0.92,
0.96) and Lower Himalaya (0.88, 0.82) for 2004–05 and 2005–06 winter respectively. Further, estimated snow surface temperature
was also verified with snow-cover information collected by manned observatories and area delineated by thematic maps of snow
surface temperature was validated with the different snow climatic zones of NW-Himalaya. 相似文献