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Petrofacies Evolution and Sedimentation History of the Gondwana Sequences in Nepal (a Comparison with Peninsular India)

R. P. Sitaula1, A. Uddin1, and B. N. Upreti2
1Department of Geology and Geography, Auburn University, 210 Petrie Hall, Auburn, AL 36849, [email protected]
2Institute of Science and Technology, Tribhuvan University, Kirtipur, Kathmandu, Nepal

Distribution of Gondwana sequences is well-preserved in several cratonic basins of peninsular India. These sequences have been also found as discontinuous patches in extra-peninsular India. Though these Gondwana units have similar provenance, there are marked differences in their lithology, thickness and depositional environments of peninsular India and extra-peninsular India.

In Nepal, the extra-peninsular Gondwana sequences are found along the Lesser Himalaya in Surkhet, Dang, Palpa and Barahachhetra. Sedimentation continued from the Carboniferous through early Miocene with major unconformities which also record a shift in sediment provenance from cratonic India to the Himalayan orogenic belt. The Tansen Group (2400 m) in Palpa consists of Sisne Formation (Lower Gondwana), Taltung and Amile formations (Upper Gondwana), Bhainskati and Dumri formations (Post Gondwana) with lithologies ranging from diamictite, sandstone, shale to quartz-arenites. The sequence in Barahachhetra (eastern Nepal) however is thin and records only Permo-Carboniferous deposition.

The Gondwana sequences of Nepal have been identified as potential rock units for petroleum resources. The potential source units are Sisne, Amile and Bhainskati formations whereas potential reservoir units are Amile and Dumri formations of Tansen Group and their equivalent units. The Gondwana sequences of Nepal (extra-pennisular India) can be compared with Gondwana sequences of the Damodar basin (peninsular India) which is more complete and also located close.

We plan to compare and contrast the Gondwana sequences from these two areas through petrofacies analysis and heavy mineral study.

AAPG Search and Discover Article #90087 © 2008 AAPG/SEG Student Expo, Houston, Texas