- Accueil
- volume 9 (2006)
- number 3-4 - Han-sur-Lesse Symposium - nov. 2004
- CONTRIBUTION OF A SEDIMENTARY STUDY TO THE KARSTIC EVOLUTION CONCEPT OF A CHALK CAVE OF THE WESTERN PARIS BASIN (NORMANDY, FRANCE)
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CONTRIBUTION OF A SEDIMENTARY STUDY TO THE KARSTIC EVOLUTION CONCEPT OF A CHALK CAVE OF THE WESTERN PARIS BASIN (NORMANDY, FRANCE)
Abstract
The Petites Dales cave is a favourable site for studying the sedimentary fillings of the chalk karst of the Western Paris Basin. The study of the fillings is based on the lithological characterization and mineralogical and chemical comparisons between the karstic sediments and the likely sedimentary sources (insoluble residue of chalk, clay-with-flints, loess). Results show that there are three main families of sediment in the Petites Dales karst: brown clayey silts, beige silts, pale beige silts. The karst sediments essentially originate in the mechanical erosion of loess. The insoluble residue of chalk, coming from the chalk weathering, is only located in the brown clayey silts, and constitutes a weak amount of this sediment type. According to these results, they are proposed three conceptual models of hydrosedimentary behaviour of the Petites Dales karstic system that could have resulted in such an intra-karstic deposition sequence. The integration of the sedimentary data into the morphological study of the galleries and their arrangement contributes to the conceptualization of an evolution pattern of the underground network in its paleogeographic context.