Holocene hydrosedimentary dynamics of the Cosson river (Loir-et-Cher, France) - GéoHydrosystèmes COntinentaux - EA6293 Accéder directement au contenu
Communication Dans Un Congrès Année : 2018

Holocene hydrosedimentary dynamics of the Cosson river (Loir-et-Cher, France)

Résumé

Climatic oscillations and anthropogenic perturbations have a great influence, at multiple spatial and time scales, on hydrosedimentary dynamics and the morphology of rivers. In particular, numerous studies emphasize on changes in fluvial regimes occurring during the post-LGM deglaciation period. Though most of the Holocene evolution of rivers seems to be linked to climatic fluctuations, it is essential, when focusing on historical periods (i.e. post- Bronze Age), to take into account and try to quantify the influence of anthropic activities on such an evolution. The Cosson watershed, located south of the middle Loire river section, flows on the Miocene fluvio-lacustrine formations of the Sologne region. Alluvial terraces in the watershed give evidence of a common evolution between the Loire and Cosson rivers before they separate during mid- Pleistocene times. In the Chambord National Domain, analyses of high-resolution Digital Elevation Models derived from airborne Lidar data show a complex network of multiple channels on the Cosson river (channeled since 15th century times) floodplain surface. Core drillings have been carried out in the floodplain to precise the Holocene hydrosedimentary dynamics of the river. Ages of alluvial deposits have been obtained using radiocarbon dating. Results show that the Holocene period can be divided in two principal sequences : a basal sequence, several metres thick, composed of coarse alluvium (coarse sand and gravels) and a top sequence about 1m-thick consisting in silty-clayey materials alternating with sandy layers. Datings place the transition between the two sequences around 1500 and 1800 yrs BP, whereas no major change seems to occur in hydrosedimentary dynamics at the base of the Holocene. Complementary work on the alluvium, such as grain-size, organic matter and palynological analyses are being carried out. Such analyses will allow to characterize sedimentary sources, better constrain the watershed paleoenvironments, and precise the respective influence of climatic and anthropogenic forcings on the Holocene hydrosedimentary dynamics in the Cosson lowland setting, where anthropic activities (prior and posterior to the edification of the Chambord royal castle) have been well documented by archeological and historical studies.
Fichier non déposé

Dates et versions

hal-02330202 , version 1 (23-10-2019)

Identifiants

  • HAL Id : hal-02330202 , version 1

Citer

Aurélien Lacoste, Clément Laplaige, Isabelle Gay-Ovejero, Florent Hinschberger, Anaïs Chauvet, et al.. Holocene hydrosedimentary dynamics of the Cosson river (Loir-et-Cher, France). FLuvial Archive Group (FLAG) Biennial meeting, Sep 2018, Liège, Belgium. ⟨hal-02330202⟩
82 Consultations
0 Téléchargements

Partager

Gmail Facebook X LinkedIn More