UIS Commission on Karst Hydrogeology and Speleogenesis
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Dubois, Caroline; Lans, Benjamin; Kaufmann, Olivier; Maire, Richard; Quinif, Yves
Ghost-rock karstification in «entre-deux-mers» (gironde, france), implications for karstogenesis and karstic morphology
Karstologia
57
19
27

The formation of the Oligocene « calcaires à Astéries » in the region of « Entre-deux-Mers » is affected by a karstification with subhorizontal caves that drained rivers from swallow-holes to resurgences. Observations in quarries show that ghost-rock alterites are present. This paper describes the ghost-rocks in the quarry of Piquepoche exploiting the Frontenac stone. We have studied horizontally developed ghost-rocks with vertical extensions still containing the residual alterite. They can be badly consolidated calcarenites up to soft material which has been sampled. Speleogenesis is reviewed in the frame of the mechanical erosion of the alterite of a horizontal ghost-rock followed by an incision by free-flowing waters which form a passage with promontories and potholes. Finally, we show that ceiling anastomoses can form by ghost-rock karstification.

Entre-deux-Mers, karstification, ghost-rock, speleomorphology
0751-7688
Dubois, Caroline; Lans, Benjamin; Kaufmann, Olivier; Maire, Richard; Quinif, Yves , , Ghost-rock karstification in «entre-deux-mers» (gironde, france), implications for karstogenesis and karstic morphology , Karstologia , 57 , 19 - 27