Research

Application of doubly substituted CO2 isotopologues in carbonate Paleo-thermometer:

Carbonate paleothermometer based on the ordering of 13C and 18O into bonds with each other in the carbonate mineral lattice is a new addition to all the preexisting suite of thermometry methods.  This differs in important ways from classical carbonate-water oxygen isotope thermometer (or similar ones based on other set of phases.  Most significantly, the 13C-18O thermometer is based on a homogeneous equilibrium (an exchange reaction involving only components of a single phase).  Therefore, it rigorously constrains temperature without needing to know the oxygen isotope composition of water, or anything else besides carbonate).  This property of the 13C-18O thermometer promises to resolve many long-standing problems in the areas of paleoclimate research. Figure below describes the empirical relationship governing the distribution of 13C and 18O in calcite structure grown in a laboratory setup and samples of inorganic calcite from otoliths from ear bone of fishes collected across different latitudes with known growth temperatures.

CO2 evolution in the paleo-atmosphere; probing the soil carbonate archives:

Researchers have discovered that Earth's last great global warming period, 3 million years ago, may have been caused by levels of CO2 in the atmosphere similar to today's. 'There are two schools of thought about past warm intervals. Many scientists suggest that they were caused by ocean currents (like the Gulf Stream) moving greater amounts of warm water from the tropics to the polar regions. Others speculate that increased levels of CO2 in the atmosphere initiated warming all over the planet. We are using supercomputing technology combined with clumped isotope analysis of continental soil sediments to make a sophisticated reconstruction of past air temperatures. If the warming was caused by ocean currents, we would expect to see cooling at the tropics and warming at the poles. Conversely, if CO2 was the cause then we would expect both the tropics and the poles to warm.

Reconstruction of paleo-diet using stable isotopes technique:

The use of stable isotope techniques in reconstruction of paleo-diet has grown steadily during the past two decades. This trend will continue as investigators realize that stable isotopes can serve as valuable nonradioactive tracers and nondestructive integrators of how plants today and in the past have interacted with and responded to their abiotic and biotic environments. At our lab we investigate feeding habit of cretaceous reptiles based on variety of geological archives (coprolite, egg shell, bone fragments).

Research Interests:

  1. CO2 evolution in the paleo-atmosphere; probing the soil carbonate archives.
  2. Reconstruction of paleo-diet using stable isotopes technique.
  3. Understanding the extinction event in geological time.
  4. Understanding upliftment history of mountains.
  5. Carbon cycle in hydrosphere-atmosphere (Ocean, estuary, lakes etc.)
  6. Chemistry of atmospheric carbon cycle.
  7. Application of doubly substituted CO2 isotopologues in carbonate Paleo-thermometry.
  8. Development of new isotopic standard for analyses of stable isotopes in air and solid samples.
  9. Rain water isotopic composition and its variability.

Courses offered : ES 201 (Aug/Jan) 3:0 : Introduction to Earth System :

The Earth as a unique body in the solar system, concept of Geology, Geobiology and early Earth, Differentiation process, Minerals and Rocks, type of rocks, Igneous Rocks, Plutons and Volcanoes, Weathering and soils, Sediments and sedimentary rocks, Metamorphism and Metamorphic rocks, Fossils, Evolution and Extinction, Geologic time, Earthquake and the structure of the Earth, Plate tectonics, Plate tectonics and geology of the Ocean, Mountain Ranges and Geologic Structures, Geologic Evolution of India, Mass Wasting Streams, Groundwater, Glaciers, Deserts, Coastlines, Geologic resources and Planetary Geology, Paleoclimate, tools for paleoclimate investigation.


References: Graham R. Thompson and Jonathan Turk, 1991, Modern Physical Geology, Saunders. College Publishing.William F., 2001, Earth's Climate: Past and Future, Freeman. Grotzinger, J. and Freeman S., 2006, Understanding Earth, Freeman.

ES 202 (Jan) 3:0 : Biogeochemistry :

Geochemistry of the Earth, Big Bang, Nucleosysthesis, Origin of Solar system, Electronic structure of atoms, periodic tables, chemical bonds, crystals, ionic substitution, isotope geo- chronometer, chemical differentiation, chemical reactions and stability of minerals, acids and bases, salts and their ions, thermodynamics, mineral stability, clay minerals, carbonate minerals, oxidation –reduction reaction, isotope fractionation, mixing and dilution, rate of chemical processes, chemical weathering, chemical composition of surface water, geochemical cycle (C-H-O-N-S), stable isotope geochemistry, Biogeochemical cycles.

References : Biogeochemistry : An Analysis of Global Change by W.H. Schlesinger, 1997, Academic press.

Principle and application of inorganic geochemistry, Gunter Faure, 1991, Prentice Hall,

Principle of stable isotope distribution by Robert E. Crises, 1999, Oxford University Press.