Journal - Middle to Late Miocene vegetation and climate from the Siwalik sediments (Karnali River section), far western Nepal

Middle to Late Miocene vegetation and climate from the Siwalik sediments (Karnali River section), far western Nepal

Khum N. Paudayal

Central Department of Geology, Tribhuvan University, Kirtipur, Kathmandu, Nepal

Jour. Nepal Geol. Soc., Vol. 44, 2012, 33-44


Abstract

The palynological study of the Siwalik sediments from the Karnali River section west Nepal revealed a significant number of palynomorphs for climatic interpretation. Out of 110 mudstone and silty clay samples collected from the Chisapani Formation (Lower Siwalik), 31 samples were found to be rich in pollen and spores. In total more than 35 genera of plant assemblages are recorded from this formation. The Pteridophyte spores are belonging to families Cyatheaceae, Lycopodiaceae, Parkeriaceae, Polypodiceae and Pteridaceae. The angiosperm pollen were represented by families Acanthaceae (Justicia sp.), Anarcardiaceae, Caprifoliaceae, Combretaceae (Terminalia sp.), Compositae, Fagaceae (Quercus glauca and Q. lanata), Palmae, Poaceae, Polygonaceae (Polygonum sp.), and Typhaceae (Typha sp.). The gymnosperms were few in number representing from Pinaceae (Abies, Picea, Pinus and Tsuga) and Podocarpaceae (Podocarpus). The lower part of Chisapani Formation is mainly dominated by Fungal and Algal remains along with plenty of Pteridophytes and Palm pollen. This indicates that the area was humid swampy lowland with tropical to subtropical climatic condition. In the upper part gymnosperm pollen such as Abies, Picea, Pinus and Tsuga indicate significant change in the climatic conditions during and after 9.6 Ma. Palynomorph evidence suggest that tropical to subtropical climate prevailed during 16 to 12.5 Ma which was gradually becoming colder during 9.6 Ma in the foreland basin of the Nepal Himalaya.

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