A B C D E F G H I J K L M N O P Q R S T U V W X Y Z All
Lazarenko, M. A.
- Crustal Structure Along Kavali-Udipi Profile in the Indian Peninsular Shield from Deep Seismic Sounding
Authors
1 National Geophysical Research Institute, Hyderabad 500007, IN
2 Geophysical Institute of the Ukrainian Academy of Sciences, Kiev, USSR, UA
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 20, No 7 (1979), Pagination: 307-333Abstract
Deep Seismic Sounding (DSS) studies were initiated for the first time in India under a 3-year Indo-Soviet collaboration agreement starting 1972, along a 600km long roughly ENE-WSW profile which lies near 14°N latitude, extending from Kavali on the east coast of India to Udipi on the west coast.
A crustal section is depicted along the Kavali-Udipi profile, showing a large number of reflectors from about 2 km to about 50 km depth. The 600 km long section consists of 17 major blocks, besides a few smaller ones. It is cut up by 15 major deep faults and two major low angle thrusts. In addition there are 5 faults/thrusts extending to intermediate depths. The geological evolution of this part of the shield probably began in Early Proterozoic with the formation of the Dharwar geosyncline between Parnapalle and Agumbe, This was divided into two parts by the uplift of the block where Closepet granites are now exposed. The Dharwars in the eastern part are now almost completely eroded, exposing their basement. The Moho here is at an average depth of 35-36 km, going down to 38 km below Dharmavaram. In the western part, where there is a large thickness of Dharwars still present, Moho is more or less flat at a depth of 38 km, going down to 41 km below Holalkere and rising about 36 km below Chennagiri, The basement of the schist belt here varies from 4 to 7 km in depth.
The Cuddapahs must have been deposited starting near Parnapalle eastward due to en-echelon type faulting. Moho goes down from 34km below Parnapalle to 40 km below Duttaluru. The block between Maidukuru and Malepadu subsided later to create a fresh depression in which the Kurnools were deposited. In general, the basement of the Cuddapahs is at a depth of 8-10 km. The Cuddapahs, on their eastern margin, have been subjected to a major low angle thrust.
- Deep Crustal Structure at Koyna, Maharashtra, Indicated by Deep Seismic Soundings
Authors
1 National Geophysical Research Institute, Hyderabad 500007, IN
2 Geophysical Institute of the Ukranian Academy of Sciences, Kiev, USSR, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 22, No 1 (1981), Pagination: 1-16Abstract
Deep Seismic Soundings (DSS) were carried out by the National Geophysical Research Institute, Hyderabad, during December 1975-April 1976, along a profile across Koyna. The studies of the data reveal a number of reflection horizons below the Deccan Traps up to the Moho discontinuity. Below the Deccan Traps, the crustal section along this profile is cut into two blocks by a deep fault west of Koyna. The eastern block is further cut by another deep fault which affects only the deeper horizons including Moho. Recent movements along the first of these deep faults, west of Koyna, appear to be responsible for the major Koyna earthquake of 1967 and subsequent seismicity in this region. The Moho depth in the western block is around 40 km in the vicinity of the deep fault and is of about 30 km at the west coast of India. In the eastern block the Moho boundary lies at an average depth of 36 to 38 km.
The thickness of the Deccan Traps along Koyna profile varies from o.4 km in the east to about 1.5 km near the west coast. The velocity in Deccan Traps is found to vary between 4.7 to 4.9 km/sec, and in the Pre-Trap basement it varies between 5.9 to 6.1 km/sec.