Abstract
Hyderabad granitic region (HGR) forms one of the most unusual geotectonic segment of the south Indian shield. Analysis of multiparametric geological, geophysical and IGS-GPS studies have earlier suggested that this region is neotectonically uplifting at a rapid rate. We propose that consequent to such uplift, only a thin veneer of surface granitic layer now remains. In order to quantitatively examine the thickness of highly resistive granitic-gneissic crust below HGR, a audio-magnetotelluric (AMT) / controlled source AMT (CSAMT) experiment was conducted at three separate locations, situated about 50 km east of Hyderabad. The study reveals a maximum thickness of 5.5 to 6.0 km for the granitic — gneissic crust beneath HGR, which is underlain by thick low resistive exhumed intermediate (granulitic ?) crust. This finding is in sharp contrast to that of a thick granitic-gneissic crust (15–20 km) usually found in comparable late Archaean terrains elsewhere.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Barton, P.J. (1986) The relationship between seismic velocity and density in the continental crust — a useful constraint? Geophys. Jour. Roy. Astron. Soc., v.87, pp.195–208.
Catherine, J.K. and Pandey, O.P. (2005) Differential uplift between Hyderabad and Bangalore geotectonic blocks of Eastern Dharwar craton, South India. Jour. Geol. Soc. India, v.65, pp.493–503.
Christensen, N.I. and Mooney, W.D. (1995) Seismic velocity structure and composition of the continental crust: a global view. Jour. Geophys. Res., v.100( B7), pp.9761–9788.
Divakara Rao, V. (1996) Metallogeny in granites — the Indian context. In: Proceedings of the International Symposium on Applied Geochemistry, Osmania University, Hyderabad, India, pp.223–228.
Kennett, B.L.N., Engdahl, E.R. and Buland, R. (1995) Constraints on seismic velocities in the Earth from traveltimes, Geophys. Jour. Internat., v.122, pp.108–124.
Kumar, P., Yuan, X., Ravi Kumar, M., Kind, R., Li, X. and Chadha, R.K. (2007) The rapid drift of Indian tectonic plate. Nature, v.449, pp.894–897.
Pandey, O.P. and Agrawal, P.K. (1999) Lithospheric mantle deformation beneath the Indian cratons. Jour. Geol., v.107, pp.683–692.
Pandey, O.P., Agrawal, P.K. and Chetty, T.R.K. (2002) Unusual lithospheric structure beneath the Hyderabad granitic region, eastern Dharwar craton, south India. Phys. Earth Planet. Inter., v.130, pp.59–69.
Pandey, O.P., Chandrakala, K., Parthasarathy, G., Reddy, P.R. and KOTI REDDY, G. (2009) Upwarp high velocity mafic crust, subsurface tectonics and cause of intraplate Latur-Killari (M 6.2) and Koyna (M 6.3) earthquakes, India — A comparative study. Jour. Asian Earth Sci., v.34, pp.781–795.
Rai, S.S., Priestly, K., Suryaprakasam, K., Srinagesh, D., Gaur, V.K. and Du, Z (2003) Crustal shear velocity structure of the south India shield. Jour. Geophys. Res. Lett., v.108( B2) 2088, dio:10.1029/2002 JB 001776.
Rambabu, H.V. and PRASANTI LAKSHMI, M. (2005) A note on geophysical mapping of the granulite terranes surrounding the Godavari Basin. Jour. Geol. Soc. India, v.65, pp.211–216.
Rantsman, E.YA., Chetty, T.R.K., Rao, M.N., Glasko, M.P., Zhidkov, M.P. and Gorshkov, A.I. (1995) Explanatory Broacher Map of morphostructural zoning of the Himalayan belt Himalayan Fore Deep and the Indian shield. Published by D.S.T., New Delhi, India, and Russian Academy of Sciences, Moscow, Russia, pp.29.
Rastogi, B.K., Bergman, E.A. and Engdhal, E.R. (2005) Improved earthquakes locations and estimation of Pn and Sn path anomalies for India using multiple event relocation and reference events. Curr. Sci., v.88, pp.1586–1591.
Rudnick, R.L. and Fountain, D.M. (1995) Nature and composition of the continental crust: A lower crustal perspective. Rev. Geophys., v.33, pp.267–309.
Sarkar, D., Ravi Kumar, M., Saul, J., Kind, R., Raju, P.S., Chadha, R.K. and Shukla, A.K. (2003) A receiver function perspective of the Dharwar craton (India) crustal structure, Geophys. Jour. Int., v.154, pp.205–211.
Saul, J., Ravi Kumar, M. and Sarkar, D. (2000) Lithospheric and upper mantle structure of the Indian shield from teleseismic receiver functions. Geophys. Res. Lett. v.27, pp.2357–2360
Singh, A.P., Vijaya Kumar, V. and Mishra, D.C. (2004) Subsurface geometry of Hyderabad granite pluton from gravity and magnetic anomalies and its role in the seismicity around Hyderabad. Curr. Sci., v.86(4), pp.580–586.
Subrahmanyam, C. and Verma, R.K. (1981) Densities and magnetic susceptibilities of Precambrian rocks of different metamorphic grade ( southern Indian shield). Jour. Geophys. Res., v.49, pp.101–107.
Zhou, L., Chen, W.-P. and Ozalaybey, S. (2000) Seismic properties of central Indian shield. Bull. Seism. Soc. Amer., v.90, pp.1295–1304.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Singh, S.B., Ashok Babu, G., Veeraiah, B. et al. Thinning of granitic-gneissic crust below uplifting hyderabad granitic region of the eastern Dharwar craton (south Indian shield): Evidence from AMT/CSAMT experiment. J Geol Soc India 74, 697–702 (2009). https://doi.org/10.1007/s12594-009-0186-6
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s12594-009-0186-6