Ediacaran multicellular biota from Krol Group, Lesser Himalaya and its stratigraphic significance-a review

Abstract

Ediacaran multicellular biota, viz. medusoids - Kimberella cf. quadrata, Beltanella cf. gilesi, Cyclomedusa davidi, Conomedusites lobatus, Tirasiana sp., Medusinites asteroides, Sekwia cf. excentrica, Irridinitus sp. and Beltanelliformis cf. brunsae; frondoids - Charniodiscus cf. arboreus, Pteridinium cf. simplex and Zolotytsia biserialis; annelid - Dickinsonia sp.; ichnofossils - Bilinichnus sp. and metaphytic algae- cf. Proterotaenia montana, has been recorded from the Kauriyala Formation (Upper Krol) of the Krol Group, Lesser Himalaya India. The underlying Jarashi Formation (Middle Krol) has yielded frondoid forms - Pteridinium carolinaense and Charniodiscus cf. arboreus and trace fossil - Harlaniella sp. whereas the Mahi Formation (Lower Krol) has yielded medusoid - Nimbia cf. occlusa. This biota is generally cosmopolitan in nature except Dickinsonia which is restricted to Protogondwana. The Ediacaran biota is preserved at the interface of arenite / siltstone and shale which show ripple marks, rhythmic and lenticular bedding at places suggestive of tidal flat environment. The present biota is comparable with Ediacaran multicellular biota of Ediacaran (Terminal Neoproterozoic) Period known from Australia, Canada and Russia. The fossiliferous horizons are characterised by δC13 values that vary from +1% to +6% PDB. Similar isotopic signatures have also been described from other Ediacaran fossil bearing horizons from northwestern Canada, Namibia, Australia, China and north Siberia.