Speleogenesis in quartzites from the Ibitipoca Range, southeastern Minas Gerais

Abstract

The caves built in quartzites at the Ibitipoca Range are part of hierarquized underground drainage systems. Spelcogencsis was a two-stage process, following the sanding/piping model. In the first stage, porosity was generated by feldspar and phyllosilicates alteration and silica solution from quartz. The essential conditions for cave development were: (1) a large diference between local and regional base levels; (2) presence of rock layers specially susceptible to sanding and piping processes (fine-grained micaceous quartzite) and (3) a sequence of cycles of stability and uplift Different cave patterns and sizes can be explained by changes in one or more of the above conditionants.