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Ramesh, R.
- Stable Isotope Systematics in Tree Cellulose as Palaeoenvironmental Indicators - A Review
Authors
1 Physical Research Laboratory, Ahmedabad 380 009, IN
2 National Geophysical Research Institute, Hyderabad 500 007, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 27, No 1 (1986), Pagination: 154-167Abstract
Stable isotope ratios of hydrogen, carbon and oxygen in tree cellulose have been recently demonstrated as potential indicators of past climate, However, a number of problems remain to be solved before isotope dendroclimatology can be used for routine reconstruction of palaeoclimate. Here we review the existing Literature, with a special reference to the Indian context and identify key problems that deserve immediate attention.- Environmental Geology of Peninsular River Basins of India
Authors
1 School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, IN
2 Institute of Oceanography, McGill University, Montreal, CA
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 30, No 5 (1987), Pagination: 393-401Abstract
An attempt is made to evaluate the environmental geology of non-Himalayan rivers of India. These twenty river basins including eleven medium basins together drain nearly 25 per cent of the sub-continent. The annual transport of suspended sediments and dissolved salts by these rivers have been estimated to be around 370 million tonnes and 61 million tonnes respectively. The rate of physical erosion among these basins range from 799 tonnes/km2/yr to 16 tonnes/km2/yr. Similarly, chemical erosion ranged from 110 tonnes/km2/yr to 22 tonnes/km2/yr.
Among the rivers considered, the chemical composition of water indicates that Cauvery carries a large silica load (39 ppm), while the TDS is low (172 ppm), whereas Sabarmati has the highest TDS (352 ppm). Krishna waters show the highest alkalinity. In all the rivers, conductivity shows good correlation with TDS. Sediment chemistry indicates that Cauvery river sediments are most siliceous while that of Godavari are least siliceous. In both these cases, average SiO2 is higher than the Indian average river sediment. Similarly, Fe in southern river sediments is very high while P is very low compared to the Indian or world average. Apparently local geology (Shield area hard rocks in southern India and Deccan Traps in central India) control the water and sediment characteristics of the peninsular rivers.
- Potentials and Limitations of Ecosystem Analysis
Authors
1 Physical Research Laboratory, Ahmedabad, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 32, No 3 (1988), Pagination: 252-253Abstract
No Abstract.- Eocene-Oligocene Stable Isotope Stratigraphy of Kutch
Authors
1 Department of Earth Sciences, I.I.T., Powai, Bombay 400076, IN
2 Physical Research Laboratory, Navrangpura, Ahmedabad 380009, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 39, No 5 (1992), Pagination: 427-432Abstract
Developments in stable oxygen and carbon isotope studies of the sediments from oceanic realm has established their potential use as stratigraphic markers. Whereas, other schemes of stratigraphic classifications for the Cenozoic sediments of Kutch are available, this paper attempts to establish the stable isotope stratigraphy of a part of the sequence. It is observed that the δ180 and δ13C variation significantly correspond to the chronostratigraphic units of this area. The negative δ13C of the Kakdian Stage (Berwali Series) shifts characteristically to positive values in the Babian Stage (Berwali Series) and then swings back to negative values in the Bermoti Series. The Kakdian Stage and the Bermoti Series, both having negative δ13C, can be differentiated by their respective δ18O range.Keywords
Stable Isotopes, Eocene-Oligocene, Stratigraphy, Kutch.- Consideration of Analytical Uncertainties While Plotting Histograms
Authors
1 Physical Research Laboratory, Navrangpura, Ahmedabad 380 009, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 41, No 4 (1993), Pagination: 313-317Abstract
A procedure is outlined for plotting histograms taking the experimental errors into consideration. This is illustrated with an example. The Fortran program is also given.Keywords
Histograms, Analytical Uncertainties.- A Fluid-Rock Interaction Model for Carbon and Oxygen Isotopic Variations in Altered Carbonatites
Authors
1 Physical Research Laboratory, Ahmedabad 380 009, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 54, No 2 (1999), Pagination: 179-186Abstract
A fluid-rock interaction model for treating the stable carbon and oxygen isotopic variations in altered carbonatites is presented and illustrated with an example using data from the ferrocarbonatites of Amba Dongar, Gujarat. The Amba Dongar ferrocarbonatites appear to have been altered by a fluid of magmatic origin at 100 to 200°C contrary to an earlier suggestion of meteoric groundwater alteration at ∼50°C.Keywords
Isotope Geology, Ferrocarbonatite, Fluorite, Fluid-Rock Interaction Model, Carbon and Oxygen Isotopes, Amba Dongar, Gujarat.- Indian Ocean Tsunami - Assessment of its Impact and Lessons for the Future
Authors
1 Earth System Science Division DST, New Delhi - 110 016, IN
2 Institute for Ocean Management Anna University, Chennai, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 68, No 2 (2006), Pagination: 331-331Abstract
No Abstract.- Extrusive Phase of Carbonatite-Alkalic Activity in Amba Dongar Complex, Chhota Udaipur, Gujarat
Authors
1 Department of Geology, St. Xavier's College, Mumbai - 400 001, IN
2 Physical Research Laboratory, Navrangpura, Ahmedabad - 380 009, IN
3 Bhabha Atomic Research Centre, Trombay, Mumbai, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 66, No 3 (2005), Pagination: 273-276Abstract
It is noteworthy that Amba Dongar carbonatite complex has both intrusive and extrusive phase carbonatites. The stratified tuff with components of both carbonatite and nephelinite have been recently traced in western part of Amba Dongar complex. In this preliminary report we present trace and rare earth elements data and C and O isotopes of these tuffs. The C and O isotopes of the least altered tuff falls within the mantle box while the remaining samples plot in the narrow field of 16-20% in oxygen. These values are explained using simple model of water-Rock interaction.Keywords
Carbonatites, Extrusive Phase, Amba Dongar, Gujarat.- Stable Oxygen and Carbon Isotope Variations as Monsoon Proxies: A Comparative Study of Speleothems from Four Different Locations in India
Authors
1 Physical Research Laboratory, Navrangpura, Ahmedabad - 380 009, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 68, No Spl Iss 3 (2006), Pagination: 461-475Abstract
Stable carbon and oxygen isotope vanations in speleothems collected from four locations in India, viz , Gupteswar (Orissa), Dandak (Chhattisgarh), Sota (Uttar Pradesh), and Akalagavi (Karnataka), and spanning various periods within the last ˜3400 years with different growth rates (0 09 to 1 34 mm/yr), have been compared In this paper we investigate the causative mechanisms for the observed variations and the spatial coherence in the isotope signals, and discuss their similarities and differences with other sirmiar high-resolution monsoon proxy records We note that (I) monsoon rainfall, and not the cave temperature, exerts a dominant control over both the carbon and oxygen stable isotope variations, (11) the oxygen isotoprc trend during 1500 400 years ago in the Indian and Omanian speleothems are in phase, and (111) dilution due to dead carbon is limited to less than 15 %.Keywords
Speleothems, Southwest monsoon, Rainfall, Stable isotopes, Radiocarbon, Varves, Paleomonsoon.- A MATLABTM Code to Perform Weighted Linear Regression with (Correlated or Uncorrelated) Errors in Bivariate Data
Authors
1 Jackson School of Geosciences, University of Texas, Austin, TX - 78713, US
2 Physical Research Laboratory, Ahmedabad - 380 009, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 77, No 4 (2011), Pagination: 377-380Abstract
MATLABTM is a powerful, easy to use, software package suitable for many mathematical operations, which finds plenty of scientific applications. One such application is the fitting of trend lines for a given data set so as to interpret the relationship of the variance of the parameters involved. We provide here a code in MATLABTM that performs the weighted linear regression with (correlated or uncorrelated) errors in bivariate data which can handle 'force-fit' regression as well.Keywords
Weighted Linear Regression, Correlated Errors, Force Fit, Trend Line, Bivariate Regression.- Stable Carbon and Oxygen Isotope Analysis of Natural Calcite and Dolomite Mixtures using Selective Acid Extraction
Authors
1 Physical Research Laboratory, Navrangpura, Ahmedabad 380009, IN