Formación Aquidabán (huellas de una glaciación)

The Aquidabán Formation, equivalent to Brazil’s Aquidauana Formation, crops out over about 12,000 km² in the Alto Apa region and is 300 to 500 m thick. It begins with fine violet-brown to pink sandstones and continues with a sequence of tillites (fine-grained rocks with pebbles of every size), siltstones and varvites (rhythmic clay layers), with boulders up to 1 m³ of granite, gneiss or quartzite.

That sequence is usually read as the deposit of a fluvio-glacial setting. Some authors cited in the UNA study doubt that there is definitive proof of glaciation and propose mudflows instead. The Misiones Formation lies above it. Around Bella Vista Norte this unit hosts the Kururu Kua sinkholes.