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

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A Precise Zircon U-Pb Age for the Base of the BIF of the Mulaingiri Formation, (Bababudan Group, Dharwar Supergroup) of the Karnataka Craton


Affiliations
1 School of Physical Sciences, Curtin University of Technology, GPO Box 1987, Perth 6000, Western Australia, Australia
2 Geological Survey of Western Australia, Mineral House, 1 Plain Street, East Perth 6004, Western Australia, Australia
3 Department of Geology, University of Calcutta, 35 Ballygunge Circular Road. Calcutta 700 019, India
     

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SHRIMP U-Pb analyses of zircon grains from two thin dark shales believed to be syndepositional ashfall tuffs close to the base of the banded iron-formation (BIF) within the Mulaingiri Formation of the Bababudan Group (Dharwar Supergroup) of the western Kamataka Craton provide a precise age for the onset of BIF deposition in the basin. Sample 120019C, from the exact base of the BIF, gave an age of 2720 ± 7 Ma, while sample 120018C, 14.5m above the base, gave an age of 2718 ± 6 Ma. The second sample contained younger grains which may have been affected by a late thermal event.

Keywords

Geochronology, Bababudan Schist Belt, SHRIMP, BIF, Karnataka.
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  • A Precise Zircon U-Pb Age for the Base of the BIF of the Mulaingiri Formation, (Bababudan Group, Dharwar Supergroup) of the Karnataka Craton

Abstract Views: 208  |  PDF Views: 4

Authors

A. F. Trendall
School of Physical Sciences, Curtin University of Technology, GPO Box 1987, Perth 6000, Western Australia, Australia
J. R De Laeter
School of Physical Sciences, Curtin University of Technology, GPO Box 1987, Perth 6000, Western Australia, Australia
D. R. Nelson
Geological Survey of Western Australia, Mineral House, 1 Plain Street, East Perth 6004, Western Australia, Australia
D. Mukhopadhyay
Department of Geology, University of Calcutta, 35 Ballygunge Circular Road. Calcutta 700 019, India

Abstract


SHRIMP U-Pb analyses of zircon grains from two thin dark shales believed to be syndepositional ashfall tuffs close to the base of the banded iron-formation (BIF) within the Mulaingiri Formation of the Bababudan Group (Dharwar Supergroup) of the western Kamataka Craton provide a precise age for the onset of BIF deposition in the basin. Sample 120019C, from the exact base of the BIF, gave an age of 2720 ± 7 Ma, while sample 120018C, 14.5m above the base, gave an age of 2718 ± 6 Ma. The second sample contained younger grains which may have been affected by a late thermal event.

Keywords


Geochronology, Bababudan Schist Belt, SHRIMP, BIF, Karnataka.