The Serra Azul Formation, Paraguay Belt, Brazil
Milene F. Figueiredo, Marly Babinski, Carlos J. S. Alvarenga, 2011. "The Serra Azul Formation, Paraguay Belt, Brazil", The Geological Record of Neoproterozoic Glaciations, Emmanuelle Arnaud, Galen P. Halverson, Graham Shields-Zhou
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A new succession of diamictites and siltstones has been found within the Araras Group and is interpreted to record Ediacaran glaciation in the northern Paraguay Belt, Brazil. This discontinuous stratigraphic unit, named the Serra Azul Formation (Fm.) (Figueiredo et al. 2005; Alvarenga et al. 2007), is up to 300 m thick. It lies above dolomites of the Nobres Fm. and below sandstones of the Raizama Fm. At the stratotype section, the Serra Azul Fm. comprises c. 70 m of massive glacial diamictites, overlain by 200 m of laminated siltstones and rhythmites that contain sparse intercalations of very fine sandstone lenses.
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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.