The glaciogenic Bol'shoy Patom Formation, Lena River, central Siberia
Nickolay M. Chumakov, Boris G. Pokrovsky, Victor A. Melezhik, 2011. "The glaciogenic Bol'shoy Patom Formation, Lena River, central Siberia", The Geological Record of Neoproterozoic Glaciations, Emmanuelle Arnaud, Galen P. Halverson, Graham Shields-Zhou
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The Bol'shoy Patom Formation (Fm.) is part of the Upper Precambrian Patom Supergroup, which comprises a siliciclastic and carbonate succession divided into (from base to top) the Ballaganakh, Dal'nyaya Tayga and Zhuya Groups (Gr.). The supergroup was deposited within the bay-like passive margins of the Siberian craton. The Bol'shoy Patom Fm. is the lower unit of the Dal'nyaya Tayga Gr. Massive and stratified diamictites with subordinate sandstones, mudstones, siltstones, conglomerates and conglo-breccias form the Bol'shoy Patom Fm. New biostratigraphic (microfossils of Pertatataka type, Ediacaran fossils) and chemostratigraphic data (87Sr/86Sr, δ13C) point to a Vendian (Late Cryogenian and Ediacaran) age for the Dal'nyaya Tayga and Zhuya Groups. Unsorted diamictite matrix, a very wide range of size and roundness of dispersed erratic clasts, the presence of glacial grooves on boulders, dropstones and till pellets in laminated mudstones and siltstones are all evidence for intense ice rafting and ice-shelf sedimentation in the northeastern part of the Patom basin during deposition of the Bol'shoy Patom Fm.
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In recent years, interest in Neoproterozoic glaciations has grown as their pivotal role in Earth system evolution has become increasingly clear. One of the main goals of the IGCP Project No. 512 was to produce a synthesis of newly available information on Neoproterozoic successions worldwide similar in format to Hambrey & Harland’s (1981) Earth’s pre-Pleistocene Glacial Record. This Memoir therefore consists of a series of overview chapters followed by site-specific chapters. The overview chapters cover key topics including the history of research on Neoproterozoic glaciations, identification of glacial deposits, chemostratigraphic techniques and datasets, palaeomagnetism, biostratigraphy, geochronology and climate modelling. The site specific chapters for 60 successions worldwide include reviews of the history of research on these rocks and up-to-date syntheses of the structural framework, tectonic setting, palaeomagnetic and geochronological constraints, physical, biological, and chemical stratigraphy, and descriptions of the glaciogenic and associated strata, including economic deposits.