Journal article
Highly heterogeneous Precambrian basement under the central Deccan Traps, India: Direct evidence from xenoliths in dykes
Gondwana research, v 13(3), pp 375-385
01 Apr 2008
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Abstract
Crustal or mantle xenoliths are not common in evolved, tholeiitic flood basalts that cover huge areas of the Precambrian shields. Yet, the occasional occurrences provide the most direct and unequivocal evidence on basement composition. Few xenolith occurrences are known from the Deccan Traps, India, and inferences about the Deccan basement have necessarily depended on geophysical studies and geochemistry of Deccan lavas and intrusions. Here, we report two basalt dykes (Rajmane and Talwade dykes) from the central Deccan Traps that are extremely rich in crustal xenoliths of great lithological variety (gneisses, quartzites, granite mylonite, felsic granulite, carbonate rock, tuff). Because the dykes are parallel and only 4 km apart, and only a few kilometres long, the xenoliths provide clear evidence for high small-scale lithological heterogeneity and strong tectonic deformation in the Precambrian Indian crust beneath. Measured
87Sr/
86Sr ratios in the xenoliths range from 0.70935 (carbonate) to 0.78479 (granite mylonite). The Rajmane dyke sampled away from any of the xenoliths shows a present-day
87Sr/
86Sr ratio of 0.70465 and initial (at 66 Ma) ratio of 0.70445. The dyke is subalkalic and fairly evolved (Mg No.
=
44.1) and broadly similar in its Sr-isotopic and elemental composition to some of the lavas of the Mahabaleshwar Formation. The xenoliths are comparable lithologically and geochemically to basement rocks from the Archaean Dharwar craton forming much of southern India. As several lines of evidence suggest, the Dharwar craton may extend at least 350–400 km north under the Deccan lava cover. This is significant for Precambrian crustal evolution of India besides continental reconstructions.
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Details
- Title
- Highly heterogeneous Precambrian basement under the central Deccan Traps, India: Direct evidence from xenoliths in dykes
- Creators
- Ranjini Ray - Department of Earth SciencesAnil D. Shukla - Physical Research LaboratoryHetu C. Sheth - Indian Institute of Technology BombayJyotiranjan S. Ray - Physical Research LaboratoryRaymond A. Duraiswami - Savitribai Phule Pune UniversityLoyc Vanderkluysen - University of Hawaii SystemChandramohan S. Rautela - Physical Research LaboratoryJyotirmoy Mallik - Indian Institute of Technology Bombay
- Publication Details
- Gondwana research, v 13(3), pp 375-385
- Publisher
- Elsevier
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Biodiversity, Earth, and Environmental Science (BEES)
- Web of Science ID
- WOS:000254659200007
- Scopus ID
- 2-s2.0-39649101282
- Other Identifier
- 991021015468904721
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- Collaboration types
- Domestic collaboration
- International collaboration
- Web of Science research areas
- Geosciences, Multidisciplinary