What drives nearshore sediment transport controls on the depletion of beach placers at Manavalakurichi,Southwest Coast of India?     

P.K. Dinesh Kumar  R. Manimurali  M.T. Babu  K. Sudheesh  P. Vethamony  K.R. Naveen Kumar 《自然地理学》2014,35(5):411-428

An in-depth analysis has been made to simulate hydrodynamic scenarios for understanding the nearshore sediment transport controls of placer mineral depletion at Manavalakurichi, India. From the analyses of topographic configuration (extracted from Hydrographic Nautical Chart No. 2048 and data generated during year 2010), we inferred that the 5-m isobaths had broadened and exhibited shallowness. Distances between the coastline and the isobaths were found to have increased significantly over the past five decades. Along with this, the 10 and 20-m contours were found to have shifted about 35–100?m horizontally landward. These changes led to severe sediment deposition in these regions due to the changed wave energy levels and refraction patterns. Numerical simulations linking bathymetry, hydrodynamics, sediment load, and significant wave heights revealed that changes in bathymetry would amplify the wave heights and convergence of wave energy. Associated removal of sand from the high-energy zones will eventually lead to sediment starvation situations and depletion of placers in the adjacent beaches. As the observed trends of depletion generate great concern, detailed oceanographic investigations should be taken up immediately in the region. Fine-resolution hydrodynamic data-sets should prove useful for further evaluating the physical responses of the system to the altered geometry and for exploring remedial measures for restoring the heavy mineral content of the beach sand.  相似文献   

Analytical solutions of one-dimensional advection-diffusion equation with variable coefficients in a finite domain   总被引：1，自引：0，他引：1  

Atul Kumar  Dilip Kumar Jaiswal  Naveen Kumar 《Journal of Earth System Science》2009,118(5):539-549

Analytical solutions are obtained for one-dimensional advection-diffusion equation with variable coefficients in a longitudinal finite initially solute free domain, for two dispersion problems. In the first one, temporally dependent solute dispersion along uniform flow in homogeneous domain is studied. In the second problem the velocity is considered spatially dependent due to the inhomogeneity of the domain and the dispersion is considered proportional to the square of the velocity. The velocity is linearly interpolated to represent small increase in it along the finite domain. This analytical solution is compared with the numerical solution in case the dispersion is proportional to the same linearly interpolated velocity. The input condition is considered continuous of uniform and of increasing nature both. The analytical solutions are obtained by using Laplace transformation technique. In that process new independent space and time variables have been introduced. The effects of the dependency of dispersion with time and the inhomogeneity of the domain on the solute transport are studied separately with the help of graphs.  相似文献   

Hydrocarbon source potential of the Proterozoic Sirban Limestone Formation,NW Himalaya,Jammu     

Naveen Hakhoo  Bindra Thusu  Devleena Mani  Ghulam M. Bhat  Jonathan Craig  Juergen Thurow  Mateen Hafiz  Sudeep Kanungo  Sumita Koul  Waquar Ahmed 《Journal of the Geological Society of India》2016,88(6):685-692

The Proterozoic Sirban Limestone Formation (SLFm) crops out as detached allochthons in the northwest Himalaya (Jammu region, India) and has its coeval equivalents laterally disposed in the west in Salt Range, in the northwest in Abbotabad (Pakistan) and in southeast in Himachal Pradesh (India). The oil and gas occurrences have been reported from the Proterozoic successions globally and the hydrocarbon potential of the SLFm cannot be ruled out.The interbedded shales and algal laminated dolostones within the SLFm have yielded microflora comparable to those reported in the North African Neoproterozoic sandstones and the Late Proterozoic carbonates of the giant oil and gas fields of the Siberian Platform. The SLFm contains a rich and diverse biota comprising ~ 10% of the rock volume in thin section. The rich organic assemblage justified a hydrocarbon source potential analysis of the SLFm, tested in this study by Rock Eval (RE) pyrolysis.RE pyrolysis yielded a total organic carbon (TOC) content of 0.02 to 1 wt. % with very low Hydrogen Index (HI) values for the shales and TOC content averaging 0.02 wt. % for the dolostones. The organically lean shales and dolostones exhibit T_max values indicative of immature to post mature stage. But, since these values are for the samples with complex thermal and tectonic history the results may be unreliable. The highly altered organic matter and kerogen present in the SLFm had the potential to generate hydrocarbons and presently indicates no significant source potential. This study is important for understanding the hydrocarbon occurrences in the SLFm particularly in light of the recent oil and gas discoveries from the coeval Proterozoic successions.  相似文献   

New evidence for two sharp replacement fronts during albitization of granitoids from northern Aravalli orogen,northwest India   总被引：1，自引：0，他引：1  

Parampreet Kaur  Naveen Chaudhri  Albrecht W. Hofmann 《International Geology Review》2015,57(11-12):1660-1685

We present new evidence of infiltration metasomatism in granitoids that were albitized in a process that produced two sharp replacement fronts, both of which are clearly visible in the field. The two fronts advanced through the original granite simultaneously, but at different rates. Here we focus mainly on the Ajitgarh intrusive in the northern Aravalli orogen of northwest India. This intrusion shows geographically well-defined metasomatic zones on the outcrop scale as well as a large volume of original ferroan granite, both of which were poorly preserved in most of the previously studied Khetri granites. Stage I metasomatism transformed the grey original granite to pink microcline–albite granite, and stage II converted the microcline–albite granite to white albite granite. Both these reaction fronts are sharp and are easily recognized in the field by their different colours. The mineralogical and chemical changes during the first stage are expressed by transformation of original oligoclase to albite, biotite (annite-rich) and hastingsite (amphibole) to hastingsite with low X_Fe values, dehydration, gain in Na, and losses in Fe and Rb. The second stage of metasomatism caused almost complete conversion of microcline to albite and complete or nearly complete disappearance of amphibole. Chemically, these changes are manifested by substantial gain in Na and extreme losses in K, Rb, Ba, Ca, Sr, Fe, and Mg. Depending on the modal abundances of amphibole, stage II albitized rocks are depleted in light rare earth elements or heavy rare earth elements or both, signifying that rare earth elements are principally hosted by mafic phases. The disparity in whole-rock δ¹⁸O values during both stages of albitization is related to the variations in modal amounts of Si-bearing phases. The replacement microstructures are in accord with the fluid-mediated phase transformations by a coupled dissolution–precipitation mechanism. The albitizing event took place at low temperatures of 350–400 °C and the fluid was metamorphic in nature.  相似文献   

Rhenium (Re)–Osmium (Os) geochronology of the Proterozoic Sirban Limestone Formation,NW Himalaya     

Naveen Hakhoo  Bindra Thusu  Ghulam M. Bhat  Jonathan Craig  Juergen Thurow  Mateen Hafiz 《Journal of the Geological Society of India》2016,88(3):267-272

The Proterozoic Sirban Limestone Formation (SLFm) exposed in a number of inliers in Jammu (India), NW Himalaya is a potential target for hydrocarbon and ore mineral exploration. The structural complexity not only makes correlation of the SLFm with coeval hydrocarbon producing Proterozoic formations in the neighbouring Salt Range in Pakistan and elsewhere in the world extremely difficult, but also limits the understanding of the genesis of sedimentary hosted mineral deposits. The base of the SLFm inliers is not exposed anywhere in the region and the age of this sequence has been suggested to range from Palaeoproterozoic to Neoproterozoic.  相似文献   

Natural Rubber Latex for Improving Ductility Characteristics of Soil: A Preliminary Experimental Investigation     

Veena  U  James  Naveen 《Geotechnical and Geological Engineering》2022,40(9):4419-4446

Geotechnical and Geological Engineering - A novel concept of applying natural rubber latex (NRL) to improve the ductility characteristics of soil is addressed in this paper. A preliminary study has...  相似文献   

On multifractality and synchronization of nonlinear stellar pulsators     

Naveen K. Bhatraju  M. K. Das 《Astrophysics and Space Science》2014,352(1):83-94

Simple models of nonlinear stellar pulsation, whose temporal behavior may reproduce some of the observed features of different classes of variable stars, have been studied. The temporal behavior of dynamical variables of these models exhibits a cascade of period doubling chaos, depending on the specific values of the various control parameters. A multifractal detrended fluctuation analysis (MFDFA) method is further used to identify the scaling behavior of such synthetic time series. The MFDFA of the considered time series, for various models of nonlinear stellar pulsation, shows that the observed multifractal nature is due to long-range correlations. The pulsating star with increased nonadiabaticity and the star with increased convective luminosity, as represented by the simulated data, is shown to possess a strange attractor with noninteger correlation dimension that lies between 2–3. Also the problem of synchronization in coupled nonlinear pulsation models has been investigated using permutation entropy—a complexity measure of the system. The computed order parameter, Γ, representing the correlation of computed permutation entropy for different segments of the simulated time series of displacement of two nonidentical oscillators, has been further used to find the critical coupling parameter for general synchronization of the oscillators.  相似文献   

Geochemistry and petrogenesis of the Palampur metavolcanics, Lesser Himachal Himalaya, India     

Dr. N. Chaudhri  Dr. B. Joseph 《Mineralogy and Petrology》1997,59(3-4):189-205

Summary The Palampur metavolcanics (PV) in the northwest Himalaya are part of the Late Archaean (2.5 Ga) Rampur flood basalt province (RFBP) which represents one of the oldest manifestation of worldwide mafic magmatism. The volcanics occur as mafic lava flows with evidence of two phases of deformation. The first phase resulted in recrystallisation which almost completely obliterated the primary mineralogy, and the second phase was of weak cataclasis. Immobile trace element ratios as well as cation percent Al - (Fe - Ti) - Mg indicate that the volcanics are tholeiitic in composition. The chemical characteristics, such as the decoupling between HFS and LIL elements i.e., distinct negative Sr, Nb and Ti anomalies in the double normalisation ratios spiderdiagram together with low Ti/Y and Zr/Y ratios, testify the rocks as low-Ti continental flood basalts. The chemical variations in the volcanics can be related to varying extents of partial melting of the mantle source(s), followed by fractional crystallisation (predominantly olivine and clinopyroxene over plagioclase). Positive correlation between LREE and Fe abundances, Ce-Nd and Y/Nd-Zr/Y data preclude any significant role of crustal contamination in the evolution of their bulk chemistry. The REE data and [Mg]-[Fe] relations rather suggest that the parental magma of the PV derived from non-pyrolitic source(s) which was heterogeneous with respect to enrichment in Zr, LREE and Fe/Mg ratios. Mantle metasomatism appears to be the main process of such source enrichment, possibly caused by the addition of a volatilerich silicate melt phase.[/ p]

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Geochemie und Petrogenese der Palampur Metavulkanite, Lesser Himachal Himalaya, Indien

Zusammenfassung Die Palampur Metavulkanite (PV), im nordwestlichen Himalaya, gehören zur spätarchaiischen (2.5 Ga) Rampur Plateau-Basalt-Provinz (RFBP), die einen der ältesten, weltweiten Phasen von mafischem Magmatismus manifestiert. Die Vulkanite treten als mafische Lavaströme auf und zeigen zwei Phasen von Deformation. Die erste resultierte in einer Rekristallisation, die nahezu den gesamten primären Mineralbestand überprägt hat. Die zweite Phase ist durch schwache Kataklase repräsentiert. Immobile Spurenelementverhältnisse, wie auch die Kationenprozent von Al- (Fe- (-Ti) -Mg, deuten eine tholeiitische Zusammensetzung der Vulkanite an. Die chemischen Charakteristika, die im unterschiedlichen Verhalten der HFS und LIL Elemente deutlich werden, deutlich negative Sr, Nb und Ti Anomalien in den zweifach normalisierten Spiderdiagrammen, niedrige Ti/Y und Zr/Y Verhältnisse, bezeugen, dass es sich um Ti-arme, kontinentale Plateaubasalte handelt. Die chemischen Unterschiede innerhalb der Vulkanite können auf unterschiedliche Grade von Aufschmelzung des (der) Mantelmaterials(e), gefolgt von fraktionierter Kristallisation (vor allem Olivin und Klinopyroxen, untergeordnet Plagioklas), zurückgeführt werden. Positive Korrelation der LREE mit Fe, wie auch die Ce-Nd und Y/Nd-Zr/Y Daten schließen eine signifikante Rolle von Krustenkontamination in der Evolution der Gesteinschemie aus. Die REE Daten und die /Mg/-/Fe/ Verhältnisse lassen eher vermuten, dass das Ausgangsmagma der PV von einem nicht-pyrolitischen Material stammt, welches bezüglich Anreicherung an Zr, LREE und Fe/Mg Verhältnis heterogen gewesen ist. Mantelmetasomatose scheint der Hauptprozeß für diese Anreicherng des Ausgangsmaterials gewesen zu sein, die möglicherweise durch Zufuhr einer silikatischen Schmelzphase, reich an flüchtigen Bestandteilen, hervorgerufen wurde.[/ p]

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Wheat crop classification using multidate IRS LISS-I data     

Sujay Dutta  NK Patel  TT Medhavy  SK Srivastava  Naveen Mishra  KRP Singh 《Journal of the Indian Society of Remote Sensing》1998,26(1-2):7-14

Multi temporal dat acquired at different growth stages increases the dimensionality information content and have advantage over single date data for crop classification. Attempt was made to select suitable single date and combination of multidate data for wheat crop classification in Nalanda district of Bihar state where pulses and other crops are also grown in rabi season. Amongst the single date data February data was found to be better for wheat classification in comparison to November. January, March and April data. Combination of first two principal components each derived from IRS LISS-I four band data acquired in January and February was found to be the best set. Wheat classification accuracy achieved was 94.54 percent.  相似文献   

Analytical solutions to one-dimensional advection–diffusion equation with variable coefficients in semi-infinite media     

Atul Kumar  Dilip Kumar Jaiswal  Naveen Kumar 《Journal of Hydrology》2010,380(3-4):330-337

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