Kaveri crater — an impact structure in the precambrian terrain of southern India

Subrahmanya, K. R. and Prakash Narasimha, K. N. (2017) Kaveri crater — an impact structure in the precambrian terrain of southern India. Journal of the Geological Society of India, 90 (4). pp. 387-395. ISSN 0974-6889

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Abstract

The region to the east of Palghat gap is of low elevation and nearly circular in shape. It forms a part of the Kaveri river basin. The predominantly gneissic terrain is surrounded by the charnockitic hill ranges, prominent among which are Nilgiris and Biligirirangan to the north; and Anaimalai and Kodaikanal to the south. The charnockite massifs have a steep slope facing the circular feature and a gentler slope in the opposite direction. Fractures/faults/shear zones are noticed in many parts. The Bouguer anomaly in the gneissic terrain is elliptical in shape and positive, relative to the surrounding elevated region. The magnetic contours are also elliptical and the magnetic basement is deeper by about one km compared to regions in the periphery. The shallow seismic velocity picture from Chennimalai to Palani indicates a graben structure. The velocity structure also depicts a 4--5 km Moho upwarp near Chennimalai. Junction between the gneissic and charnockitic terrain and even beyond, is marked by the presence of pseudotachylites and breccia. Field and petrographic studies indicate presence of suevite, Planar Deformation Features (PDF), Planar Fractures, diaplectic glass of quartz and plagioclase and spherical inclusion in suevite. These evidences taken together point to an extra-terrestrial impact which created a crater of approximately 120 km in diameter. Several lines of indirect evidences point to Neoproterozoic age for the impact. Kaveri Crater is the fourth largest crater on the surface of the Earth; other larger craters being Vredefort (160 km), Chicxulub (150 km) and Sudbury (130 km).

Item Type:	Article
Subjects:	F Earth Science > Geology
Divisions:	Department of > Earth Science
Depositing User:	C Swapna Library Assistant
Date Deposited:	20 Jun 2019 06:09
Last Modified:	20 Jun 2019 06:09
URI:	http://eprints.uni-mysore.ac.in/id/eprint/3470

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