First record of late Devonian-early Carboniferous palynoflora from the Lipak Formation, Spiti Basin, Tethyan Himalaya, India, and their biostratigraphic implications

The present work elucidates palynofloral records from the Lipak Formation (late Devonian– early Carboniferous) of the Spiti Basin. The study has been carried out from three different sections of Spiti and Pin valleys to look for the signatures of terrestrial plants in the Tethyan realm and assess the relative palynodating of the studied sediments. The recovered palynoassemblage from the exposures of Lipak Formation, near Takche Locality, Spiti Valley, mainly comprises spores and has the dominance of Verrucosisporites, Dictyotriletes, Lophozonotriletes, Convolutispora followed by subordinate occurrences of Rugospora, Cymbosporites and Knoxisporites along with reworked pollen grain Plicatipollenites. The recovered palynoassemblage of Lipak Formation exposure at Guling Village of Pin Valley comprises Spelaeotriletes, Tricidarisporites, Calamospora, Callumispora and reworked pollen grains. The reworked pollen grains are characterised by the dominance of Faunipollenites, Scheuringipollenites and Parasaccites and followed by subordinate occurrences of the Densipollenites, Striatopodocarpites, Platysaccus, Alisporites, Striomonosaccites, Chordasporites and Verticipollenites pollen grains. The exposure of this Formation near Muth Village of Pin Valley is found to be palynologically barren. The recovered palynoflora is correlated with palynofloral records of the Tethyan realm of India and palynofloral records from coeval sequences worldwide. The recovered palynocomposition shows a close resemblance to Retispora lepidophyta–Verrucosisporites nitidus (LN) and Vallatisporites verrucosus–Retusotriletes incohatus (VI) Assemblage zones of Western Europe and Cordylosporites–Verrucosisporites Biozone of Argentina which indicates that studied section of the Lipak Formation is upper Famennian to early Tournaisian age. The recovered reworked palynomorphs belong to the Permian age, which may be deposited in the Lipak Formation through stratigraphic leakage. Palynomorphs include spores of affinities of Zygopteridiales, Marattiales, Botryopteridales, Equisetales/Noeggerathiales/Sphenophyllales group of plants. In contrast, palaeobotanical affinities of pollen grains are linked with the Filicales, Cordaitales and Glossopteridales group of plants.