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, IConotheca 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.

Age and implications of the phosphatic Birmania Formation, Rajasthan, India

“…Secondly, despite concerted efforts, no small shelly fossils, conodonts or other Phanerozoic microfossils (or macrofossils) have been recovered from the Birmania Formation to date. As shelly fossils are common in Phanerozoic phosphorites, notably in the Cambrian Tarnawai and Tal formations in the Himalaya (Mostler, 1980;Bhatt et al, 1983;Brasier and Singh, 1987), they would be expected to be present if the Birmania Formation is Cambrian or younger. Thirdly, although some Cambrian or younger sandstones from Rajasthan may lack Cambrian-aged zircon grains, out of eight biostratigraphically constrained Cambrian sandstone samples with published detrital zircon ages (including one from Rajasthan) only one sample, from the Lesser Himalaya, is known to lack latest Neoproterozoic or early Cambrian age grains.…”

The Lower Cambrian Fossil Record of the Soviet Union

“…11, panel 56), which occurs at the base of the Nemakit-Daldyn Horizon (Missarzhevsky, 1973). Protohertzina was widespread over the entire Siberian Plat- form, and in Kazakhstan, Mongolia, China, the Lesser Himalayas, and western North America (Conway Morris and Fritz, 1980;Missarzhevsky and Mambetov, 1981;Luo et al, 1984;Nowlan et at, 1985;Brasier and Singh, 1987;Hamdi, 1989). In the Maly Karatau , Mountain Shoria, and Mongolia, Proto hertz ina cultrata Missarzhevsky occurs up to the Botomian.…”

A bradoriid and brachiopod dominated shelly fauna from the Furongian (Cambrian) of Västergötland, Sweden

“…67B, E, G) lack longitudinal striation. H. insolitus or similar tubes with transversal annulation and longitudinal stiation are also reported from the lower Cambrian of India (Brasier and Singh 1987), South China (Esakova and Zhegallo 1996), Australia (Skovsted and Peel 2011), lower-middle Cambrian of Laurentia (Skovsted and Holmer 2006), and middle-upper Cambrian of Kazakhstan (Esakova and Zhegallo 1996).…”