Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

K. N. Prabhakar ¹, P. L. Zutshi ¹

Affiliations
1 KDMIPE, ONGC, Dehradun, IN

Abstract

Regional study of subsurface data of sedimentary basins on the East coast of India to the south of 18° North latitude has led to an appreciation of tectonic styles and sedimentation histories of Krishna-Godavari, Pennar Palar, and Cauvery basins. Tectonics and evolutionary history is understood through three distinct episodes of evolution viz. 'lnterier Fracture', 'Pull Apart' and 'Shelf Sag/Tilt'. These episodes being a part of structural development of passive margins are complicated by phase overlap and shear tcetonics associated with differential movements during the long flight of the Indian sub-plate. The block movements along the major planes of weakness has generated different sub-basins separated by ridges both in Krishna-Godavari and Cauvery basins.

These sedimentary basins have 3-8 kms, of sediments. Punctuated with major unconformities they range in age from Proterozoic to Recent. In the outcrops present on the western margin of the basins the stratigraphic record is less complete when compared with subsurface stratigraphic succession. The presence of subsurface Gondwana sediments has been confirmed into Krishna-Godavari basin. The metasediments present above basement both in Krishna-Godavariand the Pennar basins are suggested to be equivalents of Pakhals/Cuddapahs.

Keywords

East Coast Basin Evolution, Krishna-Godavari, Pennar-Palar, Cauvery.

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V. B. Prasad ¹, P. L. Zutshi ²

Affiliations
1 Geology Section, ONGC, 4th Floor, Avani Bhavan, Chandkheda Campus, Ahmedabad - 380 005, IN
2 "Vidhata", 1, Prem Kala Vihar, Panditwari, Dehra Dun, IN

Abstract

This study pertains to subsurface interpretation of thrust belt area of Jawalamukhi in Himachal Pradesh. Stratigraphy and seismic data with the drilled well information has been collated for correlation and interpretation. The known stratigraphic sequences of Meso-Proterozoic, Lower Dharmsala, Upper Dharmsala and Siwahk have been rendered into subsurface mappable seismic units. Subathu has not been recognized in subsurface in the area under study. Isochron map of each unit is presented. The structural features brought out north of Jawalamukhi and Lambagraon are indicative of syntectonism. Tectonic model of the "thrust belt" is brought out for Jawalamukhi, Johr and Drang thrusts in time domain. A pioneering effort in seismic data interpretation in a thrust belt area in the Himalayan Belt involving the synthesis of surface geology and subsurface seismic data is presented.

Keywords

Jawalamukhi, Seismic Data, Siwaliks, Dharmsala, Meso-Proterozoic, Thrusts, Stratigraphy And Tectonics, Himachal Pradesh.

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