Sandstone caves on Venezuelan tepuis: return to pseudokarst?
- Permanent Link:
- Sandstone caves on Venezuelan tepuis: return to pseudokarst?
- Series Title:
- Aubrecht, R.
Å mída, B.
- Publication Date:
- Subjects / Keywords:
- Sandstone Caves ( local )
Speleogenesis ( local )
Tepuis ( local )
Pseudokarst ( local )
Lateritization ( local )
Dissolution ( local )
- serial ( sobekcm )
- Venezuelan table mountains (tepuis) host the largest arenite caves in the world. The most frequently used explanation of their origin so far was the â€œarenizationâ€ theory, involving dissolution of quartz cement around the sand grains and subsequent removing of the released grains by water. New research in the two largest arenite cave systems â€“ Churi-Tepui System in Chimanta Massif and Ojos de Cristal System in Roraima Tepui showed that quartz dissolution plays only a minor role in their speleogenesis. Arenites forming the tepuis are not only quartzites but they display a wide range of lithification and breakdown, including also loose sands and sandstones. Speleogenetic processes are mostly concentrated on the beds of unlithified sands which escaped from diagenesis by being sealed by the surrounding perfectly lithified quartzites. Only the so-called â€œfinger-flowâ€ pillars testify to confined diagenetic fluids which flowed in narrow channels, leaving the surrounding arenite uncemented. Another factor which influenced the cave-forming processes by about 30% was lateritization. It affects beds formed of arkosic sandstones and greywackes which show strong dissolution of micas, feldspars and clay minerals, turning then to laterite (â€œBarro Rojoâ€). The main prerequisite to rank caves among karst phenomena is dissolution. As the dissolution of silicate minerals other than quartz appears to play not only a volumetrically important role but even a trigger role, these arenitic caves may be ranked as karst.
- Original Version:
- Geomorphology, Vol. 132, no. 3-4 (2011-09-15).
- Source Institution:
- University of South Florida Library
- Holding Location:
- University of South Florida
- Rights Management:
- This object is protected by copyright, and is made available here for research and educational purposes. Permission to reuse, publish, or reproduce the object beyond the bounds of Fair Use or other exemptions to copyright law must be obtained from the copyright holder.
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