7200 years of Rhône river flooding activity in Lake Le Bourget, France: a high-resolution sediment record of NW Alps hydrology

Abstract

To cite this version:Fabien Arnaud, Michel Revel, Emmanuel Chapron, Marc Desmet, Nicolas Tribovillard. 7200 years of Rhône river flooding activity in Lake Le Bourget, France: a high-resolution sediment record of NW Alps hydrology.. Holocene, SAGE Publications, 2005, 15, pp.3, 420-428. 10 C dated core from Lake Le Bourget (Savoie, France), spanning the last 7000 years. The strong correlation (R > 0.85) of the MS with the silicateborne suite of elements (Si, Al, Fe, Mg, K) and anti-correlation with the carbonate content (R = -0.87) allows to use it as a proxy for the fluctuations of the abundance of river-borne clastic fraction versus authigenic carbonates in sediment. As the Rhône River is the only one bringing a significant amount of silicate minerals to the coring site, the MS downstream is interpreted as a proxy of the Rhône suspended load discharge in Lake Le Bourget. This is confirmed over the last 3000 years by the good match with the evolution of hydrographical activity of the Rhône river as it is known through geomorphological studies of well-dated archaeological sites (Bravard et al., 1992; Bravard, 1996). Over the last 7200 years, the record is consistent with the regional evolution of lake water-level fluctuations (Magny, 2004). Hence, while the intensity of the MS signal seems to be widely affected by the human impact on soil stability, the timing of the period of enhanced hydrological activity appears to be mostly climate related and should thus constitute a first step toward a high resolution (< 8 yrs) continuous history of hydrological conditions in NW Alps.

A multi-proxy, high-resolution record of peatland development and its drivers during the last millennium from the subalpine Swiss Alps

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