Karstic morphology control in non-carbonate rocks: Santana basin, middle Paraiba do Sul river valley, Brazil (original) (raw)

Hundreds of karstic features (n = 266) and gullies (n = 80) are indentified in an area (56.3 km 2 ) of non-carbonate rocks which include pure quartzite (Q), impure quartzite (Qi) and gneiss (G) within the Santana Basin (286 km 2 ), a part of Middle Paraiba do Sul River Valley, southeastern Brazil. Karstic features include caves (n = 32), collapsed dolines (n = 23), solution dolines (n = 209), Sinkholes (n = 02) and resurgences (n = 02). Gullies include active gullies (n = 46) and stabilized gullies (n = 34). Other general features as knickpoints (n = 06) and captured valleys (n = 03) were also indentified. We used GIS to study correlations between the presence of features, precise lithology and relief to indentify possible controls. The results suggest a lithological control on the karstic features with higher frequency of caves, collapsed dolines, sinkholes and resurgences in pure quartzite (Q) and in areas with high relief, but there is no lithological control on solution dolines. Gullies, knickpoints and captured valleys are also not controlled by lithology or relief. The results suggest a fluvial control of gullies and depositional features in valley bottoms caused by headward erosion, after underground captures or knickpoint disruption.

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