Microfossils and Precambrian–Cambrian boundary stratigraphy at Maldeota, Lesser Himalaya

Abstract

An assemblage of problematical microfossils of Precambrian–Cambrian boundary age is redescribed from the Chert–Phosphorite Member, at the base of the Lower Tal Formation of Maldeota in the Lesser Himalaya of India. This assemblage has previously been ascribed to various ages, from Precambrian to Cretaceous, but is held by us to contain:Maldeotaia bandalica, Protohertzina anabarica group, trumpet-shaped elements, acicular elements A & B, ?Conotheca sp.,Ovalitheca cf.multicostata, allathecid sp. A,Barbitositheca ansata, Hexangulaconularia cf.formosa, Coleoloides aff.typicalis, Hyolithellus aff.insolitus, H.cf.isiticus, H. vladimirovae, Spirellus shankari and Olivooides multisulcatus. These compare closely with assemblages found above the base of the first,Anabarites trisulcatus–Protohertzina anabarica Zone in China and in the second,Pseudorthotheca costata Zone of southern Kazakhstan. The stratigraphic setting of the Krol–Tal succession is reviewed and several similarities are noted between the Precambrian–Cambrian boundary successions of Lesser Himalaya in India and of Yunnan and Sichuan in Southwest China, indicating that correlation between them is possible at several levels.