Chapter 46 The Serra Azul Formation, Paraguay Belt, Brazil

Abstract

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.

Investigating mid‐Ediacaran glaciation and final Gondwana amalgamation using coupled sedimentology and 40Ar/ 39Ar detrital muscovite provenance from the Paraguay Belt, Brazil

“…Figueiredo et al . () suggested that the diamictite is not observed in the west due to non‐deposition or erosion after deposition. Erosion is not considered to be a likely possibility, given that accommodation space is generally considered to increase in the wake of glaciation.…”

“…In a subsequent contribution, Figueiredo et al . () stated that the Serra Azul Formation is between 250 m and 300 m thick in the region where it is completely exposed; however, the base of the Serra Azul Formation was not documented. McGee et al .…”

Chapter 1 The geological record of Neoproterozoic ice ages

“…1.4, Table 1.4). The Araras Group in the northern Paraguay Belt, in particular, has been the subject of interdisciplinary studies and preserves some of the best evidence for Ediacaran glaciation in South America (Figueiredo et al 2011). New entries to the South American database include the sections in Peru, Uruguay and Argentina as well as the Moema laminites in Brazil.…”