Francis A. Macdonald, David S. Jones, 2011. "The Khubsugul Group, Northern Mongolia", The Geological Record of Neoproterozoic Glaciations, Emmanuelle Arnaud, Galen P. Halverson, Graham Shields-Zhou
Download citation file:
The Khubsugul Group of northern Mongolia contains diamictites in the Ongoluk and Khesen formations that are succeeded by a stratiform phosphorite deposit and >2 km of early Cambrian dolomite. The stratigraphy of the Khubsugul Group, including the two diamictites, can be correlated with that of the Dzabkhan platform in southern Mongolia. By correlation, the Ongoluk diamictite is an early Cryogenian glacial deposit. A glaciogenic origin is inferred from the presence of striated clasts and bed-penetrating dropstones. The younger Khesen diamictite consists predominantly of a massive carbonate-clast diamictite, but also contains bed-penetrating dropstones in rare stratified facies, and is inferred to be end Cryogenian in age. The two diamictites are separated by as much as 250 m of allodapic carbonate. The phosphorite in the upper Khesen Formation (Fm.) is likely latest Ediacaran to early Cambrian in age and is separated from the glacial deposits by a major hiatus. Consequently, no links can be made between the phosphogenesis and the glacial deposits. Only limited geochemical, geochronological and palaeomagnetic results from the Khubsugul basin have been reported to date, but work is ongoing and there is strong potential for future studies.
Figures & Tables
The Geological Record of Neoproterozoic Glaciations
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.