Stratigraphical and palynological appraisal of the Late Quaternary mangrove deposits of the west coast of India   总被引：1，自引：0，他引：1  

K.P.N. Kumaran  K.M. Nair  Mahesh Shindikar  Ruta B. Limaye  D. Padmalal 《Quaternary Research》2005,64(3):418-431

The organic deposits derived from the mangrove swamps form reliable stratigraphic markers within the Late Quaternary sequence of Kerala–Konkan Basin. Three generations of such deposits have been identified. The older one is dated to around 43,000–40,000 ¹⁴C yr B.P., with a few dates beyond the range of radiocarbon. The younger ones date from the Middle Holocene to latest Pleistocene (10,760–4540 ¹⁴C yr B.P.) and the Late Holocene (<4000 ¹⁴C yr B.P.). Pollen analyses confirm that the deposits are mostly derived from the mangrove vegetation. Peat accumulation during the period 40,000–28,000 ¹⁴C yr B.P. can be correlated with the excess rainfall, 40–100% greater than modern values, of the Asian summer monsoon. The low occurrence of mangrove between 22,000 and 18,000 ¹⁴C yr B.P. can be attributed to the prevailing aridity and/or reduced precipitation associated worldwide with Last Glacial Maximum, because exposure surfaces and ferruginous layers are commonly found in intervals representing this period. The high rainfall of 11,000–4000 ¹⁴C yr B.P. is found to be the most significant as the mangrove reached an optimum growth around 11,000 ¹⁴C yr B.P. but with periods of punctuated weaker monsoons. From the present and previous studies, it has been observed that after about 5000 or 4000 ¹⁴C yr B.P., the monsoons became gradually reduced leading to drying up of many of the marginal marine mangrove ecosystems. A case study of Hadi profile provided an insight to the relevance of magnetic susceptibility (χ) to record the ecological shift in Late Holocene.  相似文献   

Exploring the Moon in the 21st century     

Ian Crawford  Mahesh Anand 《Astronomy& Geophysics》2006,47(1):1.33-1.34

Ian Crawford and Mahesh Anand report on a wide-ranging RAS Discussion Meeting on the future of lunar exploration, held in the Geological Society Lecture Theatre at Burlington House on Friday 11 November 2005.  相似文献   

Some aspects of geomorphic processes along the Goa coast through remote sensing     

V. K. Anand  G. Venkataraman  S. Vishwanathan  G. S. K. Rao 《Journal of the Indian Society of Remote Sensing》1987,15(1):49-54

This paper deals with the processes operating on the beaches of Goa, interpreted from imagery, followed by ground-truth collection and field checks. Studies on Landsat imagery bring out two distinct coastal geomorphological features, one north and the other south of Vasco-da-Gama. The beaches to the south indicate the prograding shoreline with deposition being the dominant phenomenon. The beaches to the north of Vasco-da-Gama reveal a retrograding shoreline where erosion is dominant. The presence of chimneys and stacks to the north of Vasco-da-Gama are characteristic of intensive erosional action while to the south a wide regular beach backed by a palaeo-strand line points to deposition. The pattern of the sediment load (in Band 4) is used as an index of longshore current movement. The action of erosion as against that of deposition in the two regions can be surmised from the diffused pattern vis-a-vis the uniformly wide even tone. Sand samples from the northern portion give a sorting coefficient of 1.100 while the southern portion shows a value of 0.712. It is hypothesised that the promontory on which Vasco-da-Gama lies is responsible for the formation of two different geomorphic zones.  相似文献   

Silver losses from ammoniacal solutions on complex sulphide and chalcopyrite ammonia leach residues     

S. Acharya  S. Anand  R.P. Das 《International Journal of Mineral Processing》1987,20(3-4)

Extraction and subsequent loss of silver from leach liquor during oxidative ammonia leaching of complex sulphide and chalcopyrite concentrates have been observed. The lost silver value from the leach liquor was unrecoverable when the residues were treated with ammonia-ammonium sulphate buffer (pH=9.5) solutions at 27°C. However, when the same slurry was heated to 75°C in an autoclave under an atmosphere of oxygen, almost all the silver value could be redissolved. The leach residues lost their silver absorbance property from ammoniacal solutions on repeatedly heating and cooling the leached slurries in the presence of oxygen. In this work, silver losses from ammoniacal solutions on various leach residues, synthetic iron oxides, and freshly precipitated Fe(II) and Fe(III) hydroxides are reported. None of the major constituents present in the leach residues were responsible for the silver losses but small amounts of Fe(II) associated with the residues could take up silver from the leach solutions.  相似文献   

Hydrogeomorphological studies in kallambella watershed, Tumkur District, Karnataka State, India Using Remote Sensing and GIS     

N. Lokesha  G. S. Gopalakrishna  M. J. Mahesh 《Journal of the Indian Society of Remote Sensing》2007,35(1):107-115

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Petrology and geochemistry of LaPaz Icefield 02205: A new unique low-Ti mare-basalt meteorite     

Mahesh Anand  Lawrence A. Taylor  Clive R. Neal  Shiho Tanikawa 《Geochimica et cosmochimica acta》2006,70(1):246-264

LaPaz Icefield 02205 (LAP 02205) is a new low-Ti mare-basalt meteorite that was discovered in the LaPaz Ice Field in Antarctica. This is the first crystalline lunar basalt in the US Antarctic collection and the only 5th unbrecciated mare-basalt meteorite to be discovered to date. The rock has a typical basaltic texture with tabular and elongated pyroxene and plagioclase crystals, and minor olivine grains commonly rimmed by pyroxenes. Core- to rim-zoning in terms of Fe and Mg is present in almost all pyroxene grains. Accessory minerals include ilmenite, chromite, ulvöspinel, troilite, and FeNi metal. This rock is highly enriched in late-stage mesostasis. Free silica is also abundant. In terms of texture and mineralogy, LAP 02205 displays features of low-Ti mare basalts, with similarities to some low-Ti Apollo 12 and Apollo 15 basalts. Whole-rock major- and trace-element compositions confirm the highly fractionated nature of this basalt. The whole-rock REE contents of the meteorite are the highest among all known low-Ti mare basalts. The platinum group element (PGE) contents in LAP are also enriched suggesting the possibility of endogenously enriched source regions or the PGEs generally behaved as incompatible elements during crystal fractionation under low fO₂ conditions. Trace-element contents of mineral grains in LAP 02205 display wide variations, suggesting extensive non-equilibrium crystallization. The REE concentrations in the earliest-formed minerals provide constraints on the composition of the parental liquid, which is similar to the measured whole-rock composition. Crystallization modeling of the LAP 02205 bulk composition yields a reasonable fit between predicted and observed mineral phases and compositions, except for the high-Mg olivine cores, which are observed in the rock but not predicted by the modeling. An isochron age of 2929 ± 150 Ma for phosphate minerals makes this rock one of the youngest lunar basalts known to date. The young age and specific geochemical characteristics of LAP distinguish it from those of most other low-Ti mare basalts. However, the low-Ti mare basalt meteorite, NWA 032, has a similar young age, and the two meteorites also appear to be closely related from some geochemical perspectives and might have originated from similar source regions on the Moon.  相似文献   

On non-adiabatic oscillations of gaseous systems in hydromagnetics     

Serge Pineault  S. P. S. Anand 《Astrophysics and Space Science》1973,24(1):105-115

The general variational principle obtained by Unno for the study of stellar stability is extended to include the effects of magnetic fields in the general case where the perturbations are nonadiabatic. The unperturbed configuration is non-rotating, but internal motions are possible.A general stability equation is derived, using the modified variational principle. In the simplest case, this equation is identical to the one derived by Unno except for the appearance of magnetic terms in one of the coefficients (through the Lorentz force). If dissipation is neglected, the characteristic equation reduces to the one derived by Frieman and Rotenberg in the stationary case and by Kovetz in the static case.The stability of magnetic stars against homologous oscillations is examined and the usual result for the dynamical mode is obtained.  相似文献   

The energy spectrum of cosmic ray electrons between 10 and 1000 GeV     

K. C. Anand  R. R. Daniel  S. A. Stephens 《Astrophysics and Space Science》1975,36(1):169-175

Measurements made by the Bombay Group on the fluxes of cosmic ray electrons in the energy range 10–1000 GeV have been compared with those of other workers in the same energy domain with a view to understand the present confused situation on the existing observations at these high energies. Such an analysis clearly brings out the current situation in its true perspective and highlights the care and emphasis to be placed on future experimentation in this important field.  相似文献   

On rotating isothermal configurations in the post-Newtonian approximation of general relativity     

M. M. Shara  S. P. S. Anand 《Astrophysics and Space Science》1973,24(1):117-126

The equations which govern the structure of a rotating, truncated isothermal sphere in the post-Newtonian approximation of general relativity are derived and solved numerically. Each model is parameterized by both a rotation and a relativity parameter. The density inside the configurations is tabulated and graphed as a function of both distance from the center and co-latitude. Relativistic gravitational effects are found to pull the models into states which are considerably more centrally condensed than one predicts classically. Rotation tends to flatten the isothermal configurations into oblate spheroids, though for even the largest rotation parameters the degree of flattening is only a few percent. The computed models may be similar to the cores of relativistic star clusters.  相似文献   

An Alternate Antenna Array Geometry for a GB-SAR System Used in Landslide Monitoring     

Shweta Vincent  Sharmila Anand John Francis  Elijah Blessing Rajsingh 《Journal of the Indian Society of Remote Sensing》2015,43(4):761-768

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