Crustal Processes (CrP) Group
Fundamental knowledge on various processes in space and time within the solid earth, through an interdisciplinary research of these processes is an important prerequisite to address enigmatic geodynamic problems and understanding of the nature and origin of mineral deposits and in formulating future mineral exploration strategies. The early evolution of continental crust is still a mystery and a debated topic. Many frozen information on how continents have formed, evolved and witnessed changes through a long span of more than 3.5 billion years is expected to be preserved in southern Indian terrain. Although detailed study spans more than 150 years on the Peninsular shield, there is much to be done especially because modern concepts of Precambrian geology and crustal evolution have evolved only in the last few years with the developments in science and technology and augmenting of laboratory facilities. New concepts have to be examined with new instruments and analytical techniques, particularly in the field of geochemistry, geochronology and geophysics. These efforts can lead us to vital clues that are needed for understanding of 1) how the Indian lithosphere became an ensemble of differentially evolved Archaean-Early Proterozoic cratons, overlain by mid to late Proterozoic platform basins; 2) tectonic and temporal evolution of craton, mobile belts and cover sequences;; 3) dynamics of plate motion in relation to lower and upper crustal rheology; 4) phases of acid/basic magmatism and 5) development of economically rich mineral deposits like iron, copper, chromium, manganese, gold, PGE and graphite. The southern Indian shield is enveloped by extensive deposits of sediments which are important for unravelling the climatic changes in the Indian Ocean, cycles of sea level changes, and climate history during Holocene and the uplift of Western Ghats. They are also potential areas for high hydrocarbon reservoirs.
Natural hazards, particularly the earth tremors and landslides in the south-western part of the Indian shield seem to be closely linked to the active and neotectonic (Neogene and Quaternary) activity which is often manifested along the old (Archaean or Proterozoic) shear zones or faults which may sometimes represent old regional cratonic and terrain boundaries. Detailed studies have greater relevance even in societal applications.
We plan, at the forefront of all the activities, establishment of state of art facility in a phased manner to accomplish the envisaged goals and objectives. Different groups comprising scientists with expertise on igneous petrology, metamorphic petrology, weathering processes, geomorphology and sedimentology will be formed to collect primary field data and samples for laboratory studies. The exact location of key field areas will be designed in such a way that all aspects of field geology can be integrated to help in explaining the geodynamic evolutionary model for the SGT. Fresh quarries, wherever available, will be studied to understand interrelation between rock types, understand chronology of geological events and collect fresh samples for petrological and geochemical studies. Samples will be analysed for trace, major and REE to characterise and understand their petrogenesis. Igneous intrusives will be sampled and their relation to the structures will be examined. Also, the relationship between structures and mineral growth will be examined in view of U-Th-Pb monazite dating.
Follow-up on fieldwork will consist of geochronological studies, including U-Th-Pb dating of monazites using the electron microprobe and XRF, Ar-Ar dating of mica, in order to better understand the tectono-metamorphic evolution of SGT. Laser Raman spectroscopy and fluorescence studies will be carried out to understand nature of fluids that moved through rock types and detrital quartz grains to characterise and study fluid inclusions and their role in metamorphism, mineralisation and in understanding hydrocarbon inclusions. Studies on sediment cores will provide information on the changes in sea level, monsoonal variations etc. These results in combination with the proposed isotope and radiocarbon work would help in reconstruction of past events and changes.