GIS@development December 2002: "GIS and the Tectonics of the Eastern Ghats, India"

Geographic Information System (GIS) has greatly improved the efficiency and expanded the possibilities of evaluation, manipulation and combination of multiple data sets. In view of variability of geological features in space and time geologists have been rather slow in making use of such a powerful tool as GIS but are now embracing this technology for a variety of applications. GIS not only saves digital data sources of spatial data but also effectively acts as visualization tool and transformation aid. Visualization is a critically important function of GIS. Earlier, by looking at maps and map patterns geoscientists used to analyze and postulate geologic structure. GIS has made a tremendous impact in manipulation and analysis of individual layers of spatial data. This can be carried out by visualizing the display of different geological objects with specific combinations which effectively create new maps. Such maps can often lead to a better understanding and meaningful interpretations.

In this contribution, we apply GIS to understand the tectonic history of the Eastern Ghats Mobile Belt, a well-known Precambrian orogenic belt of global importance. We attempt integration and superimposition of different geological features such as lithologies, structural trends, fold patterns and shear zone systems etc. from different sources of multiple scales through permutation and combination within the platform of GIS and evaluate their interpretations. We also demonstrate how a GIS approach eases data archiving and map generation for better insights and interpretational possibilities, which were not available with common traditional mapping procedures.

Resource Data and Digitization
The Eastern Ghats Mobile Belt (EGMB), which occurs along the east coast of India, has been subjected to Proterozoic collisional processes (Chetty and Murthy, 1994). The EGMB has received much attention because of its mineral wealth and its role in the reconstruction of Gondwana supercontinent. The major lithologies are charnockites, khondalite group of rocks, migmatites including other granitoids, which have been metamorphosed to granulite facies metamorphism around 3000Ma. These are subsequently invaded by alkaline and anorthositic rocks (1450-850 Ma), preferably emplaced along the shear zones at the western margins. Proterozoic metasedimentary basins of varied size and shape occur in the craton in the vicinity of the western margin of the EGMB. The EGMB is transected by across by two major Precambrian rift structures namely Godavari rift in the south and Mahanadi rift in the north. Details of geologic history of the EGMB are provided in recent reviews (eg. Ramakrishnan et al., 1998; Chetty, 1995, 2001; Chetty and Murthy, 1994, 1998; Rickers et al., 2001).

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