Serra sul diamictite of the carajas basin (Brazil): A paleoproterozoic glaciation on the amazonian craton

Abstract

This paper reports the discovery of glacial deposits of likely Siderian-Rhyacian age (2.58-2.06 Ga) in South America (Carajas Basin, Brazil), thereby expanding the potential reach of Paleoproterozoic glaciations to the Amazonian craton for the first time. Glacially derived diamictites are stacked within a hitherto unrecognized ~600-m-thick siliciclastic succession, here named the Serra Sul Formation. Well-preserved textures, with evidence of glaciotectonism and ice rafting, indicate deposition in a coastal subglacial to glacial-fed submarine fan system, in which the immediately underlying units (banded iron formation and volcanic rock) were the main source and bedrock. The Serra Sul diamictite may be correlated with any of the known Paleoproterozoic glaciations, or with none of them.