Expansion and retreat of the Jura ice sheet (France) during the last glacial maximum

摘要

In continental environments, while there is no uninterrupted record of glaciation, glacier activity can be reconstructed from the nature and geometry of sediments trapped by lake filling. Examination of the Combe d'Ain lake filling provides insight into the history of the Jura Mountains during the last glacial maximum (LGM). From the evidence of outcrops, borehole cores, and seismic reflection profiles of the lake filling, we show that glaciation was marked by three stages of stabilization. Then, recessional moraines marked five episodes of stabilization in the course of glacial retreat. Comparison with partial deriv ~(18)O data from ice cores of Greenland makes possible to date the last glacial maximum at 25,500-22,000 Cal. BC and glacial retreat at 22,000-17,000 Cal. BC.