In:
Collection EDYTEM. Cahiers de géographie, PERSEE Program, Vol. 6, No. 1 ( 2008), p. 39-50
Abstract:
Radiocarbon dating at the base of sediment cores retrieved from high altitude proglacial lakes Bramant and Blanc Huez (Grandes Rousses Massif 2500 m altitude) based on high resolution seismic reflection profiling, suggest that these lakes were ice free since the end of the Lateglacial period, and that their catchment areas were largely free of glaciers during the first part of the Holocene. The development of a neoglacial period implying increasing clastic sedimentation in these proglacial lakes is then characterized by several rapid glacier fluctuations. During the Early and Late Bronze Age periods, for example, enhanced organic sedimentation in Lake Bramant suggest that glaciers in this part of the massif were probably smaller than today. The maximum extension of Holocene glaciers in this massif was then reached during the Little Ice Age. A synthesis of archaeological investigations and the identification of several metallic contaminations in lacustrine sediments, allow documenting the evolution at high altitude of mining activities. High content of Copper between 3770-3870 cal BP in Lake Bramant sediments can for example be related to Early Bronze Age mining artefacts recently identified between 2200 and 2600 m within chalcopyrite ore deposits next to the catchment area of Lake Bramant in the Northern part of the massif. In the southern part of the massif, two peaks highlighting high content of Silver in Lake Blanc Huez recent sediments can similarly be related to a well documented Lead Silver mining industry at the lake shore between AD 1236 and 1330. The origins of an older peak in Silver in Lake Blanc Huez and of a clear peak in Copper and Lead during the Roman period between AD 1 15-330 in Lake Bramant, are however not clearly understood.
Type of Medium:
Online Resource
ISSN:
1762-4304
DOI:
10.3406/edyte.2008.1027
Language:
French
Publisher:
PERSEE Program
Publication Date:
2008
