The late quaternary sedimentary infill of Lake Annecy (northwestern Alps): an overview from two seismic-reflection surveys
Beck, C.; Van Rensbergen, P.; De Batist, M.; Berthier, F.; Lallier, S.; Manalt, F. (2001). The late quaternary sedimentary infill of Lake Annecy (northwestern Alps): an overview from two seismic-reflection surveys. J. Paleolimnol. 25: 149-161. http://dx.doi.org/10.1023/A:1008175728826 In: Journal of Paleolimnology. Springer: Dordrecht; London; Boston. ISSN 0921-2728; e-ISSN 1573-0417, more |  |
| Author keywords | deglaciation; Holocene; Alps; lacustrine sedimentation; seismic stratigraphy; slumping |
| Authors | | Top | - Beck, C.
- Van Rensbergen, P., more
- De Batist, M., more
| - Berthier, F.
- Lallier, S.
- Manalt, F.
| |
| Abstract | The sedimentary fill of Lake Annecy (northwestern Alps) - related to the last glacial/post-glacial episode - was investigated through high resolution (sparker) and very high resolution (2.5 kHz) seismic-reflection surveys. A seismostratigraphic approach led to subdivision of a 150 m-thick pile (maximum thickness in axial part) into five units. Basal units (1 and 2) represent an imbrication of subglacial and glacio-lacustrine deposits, close to the grounding line of the glaciers'' fronts (respectively at the northern and southern terminations of the lake). The first acoustically well-stratified unit (3) developed during a fast retreat of the glaciers fronts far from the lake basin, and a progradational alluvial regime, with abundant underflows, in a lake larger than the present one. Unit 4 represents the progressive decrease of this clastic input mixed with the progressive development of in situ bio-induced production. As in many other alpine lakes, a topmost unit (5), relatively thin (about 8-10 m) and with a conspicuous drape configuration, is the signature of the Holocene interglacial climatic conditions with a sedimentation rate of about 1 mm/yr. On the lacustrine basin slopes, slumps and debris flow occurred mainly within Unit 3; they may be due to, either climate-induced high rate terrigenous sedimentation, or/and to a period of increased seismo-tectonic activity. |
|
