INTENSIVE SUBGLACIAL DRAINAGE AND THE INCEPTION OF ESKERS TRIGGERED BY LATEGLACIAL SEISMOGENIC ISOSTATIC REBOUND; STOCKHOLM AREA, EASTCENTRAL SWEDEN

The spatial initiation of the esker systems of the Stockholm area, eastcentral Sweden, cannot be explained by simple models focusing on the fluctuations of the climatic signals. This is due to the required timelag of the Fennoscandinavian ice sheet to respond to the global warming era during early Preboreal. The reported seismogenic isostatic rebound event in the Stockholm area during the late- and post glacial deglaciation may remarkably fits into a scenario consisting the sudden drainage (jökulhlaup)of a proposed subglacial lake (Promälaren Lake), formed earlier to the north of the study area. Sedimentological analyses and hydraulic calculations are performed to estimate the peak flow rate and the volume of the water drained during the jökuhlaup event into the outlet channels, some deeply cut into the bedrock. The coincidence of high subglacial uplift rates with the initiation of subglacial esker ridges indicates seismogenic isostatic rebound effects to be possible as a triggering mechanism for the drainage of a subglacial lake during a rapid ice sheet decay event.