Les remplissages détritiques endokarstiques.
Contribution méthodologique à la lecture des mémoires paléogéographiques et environnementales.
Application aux systèmes karstiques de Choranche (Vercors) et d'Orgnac (Bas-Vivarais).

Abstract : This thesis fits within the framework of researches led on the continental natural recorders, and their interest as an environmental and climatic memory. Indeed, a lot of studies was led on alpine glaciers, tree-rings, lacustrine deposits and speleothems among others things. In front of the wealth of informations extracted about past environmental and climatic evolutions, for local in regional scales and with an annual in ten-year resolution, it appears very interesting to study endokarstic detritic deposits and to estimate the memory of these natural archives.

In this study, we have two aims. Firstly, it's necessary to understand the deposit dynamics sediments by, as well as possible, integrating specificities and constraints induced by endokarstic environment. By adjusting the methods of the classic sedimentology, we try to understand better the sedimentation conditions in the underground environment, with the intention of a better reading of accumulated deposits. Secondly, our work aims at characterizing, by the construction of "identity cards", the various modes of sedimentary trapping recognized, for a typology. This identification is important insofar as it could allow, eventually, to work on old endokarstic deposits, whose sedimentation dynamic is not observable any more today. So, the environmental data archived by these deposits would be better deciphered.

Through the study of two complementary sites, the caves of Choranche in Vercors and the aven of Orgnac in Bas-Vivarais, we undertook a high resolution analysis of various fine detritic infillings, always active or inherited. The used methods were borrowed from sedimentologists, such as granulometry, signal treatment, Passega images and measures of colorimetry or magnetic susceptibility. An important part of karstologic methods is also integrated, to put back our object, endokarstic fine sediments, in their context.

From this double approach, it come out that endokarstic detritic sediments function as a recorder of the local environmental fluctuations ; drainages being the main vector of transmission of information. It is also a great complexity of the filing that was brought to the fore, and which is expressed on several levels of our research. So, the choice of the “identity card” to characterised the different types of sedimentary trapping must be worked again to try to see if a finer identification is possible, in order to reach a better reproductibility. On the other hand, from the 14C datings of charcoals, the chronology of this archives could not be clearly highlighted. Through various studied sedimentary signals, it seems that the resolution can be very variable; being directly subjected to sedimentation dynamics, but also subjected to sites. These first results are at the root of opening researches, with many prospects, among which the datings and in particular the 210Pb method, occupy a place of choice. It is one of the most important keys of reading, compared to the final goal considerate in this thesis : the possibility of paleoenvironmental and paleoclimatic reconstructions from the endokarstic detritic archives.
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Contributor : Anne-Sophie Perroux <>
Submitted on : Monday, October 29, 2007 - 9:14:53 AM
Last modification on : Thursday, January 11, 2018 - 6:20:38 AM
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Anne-Sophie Perroux. Les remplissages détritiques endokarstiques.
Contribution méthodologique à la lecture des mémoires paléogéographiques et environnementales.
Application aux systèmes karstiques de Choranche (Vercors) et d'Orgnac (Bas-Vivarais).. Minéralogie. Université de Savoie, 2005. Français. ⟨tel-00011125v2⟩

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