El registro sedimentario del lago Sant Maurici (Pirineos Centrales)

Abstract

The St. Maurici Lake (1.004818 E, 42.580801 N, 1924 m a.s.l.) is located in the eastern area of >Parc Nacional d’Aigüestortes i Estany de Sant Maurici>, Central Pyrenees, Catalonia. The lake occupies an overexcavated basin behind a terminal moraine. This paper aims to reconstruct the evolution of depositional environments and their relation to climate evolution since deglaciation to the present, based on a 8.7-m long sequence retrieved in the deepest part of the lake and a preliminary chronological model with three 14C AMS dates. After the glacial retreat carbonatic very fine sands and silts without organic matter were deposited in a proglacial environment. Early Holocene sediments are massive fine sands to laminated sandy silts with increasing organic content and some sand layers. A sedimentary hiatus occurred during the mid Holocene and the sedimentation re-started after ca. 4 ka with deposition of organic facies. Changes in clastic content reflect centennial scale run-off variability during the last millennia.