Transient subglacial hydrology of a thin ice sheet: insights from the Chasm esker, British Columbia, Canada

摘要: Abstract Glacier drainage systems are never steady state; instead they fluctuate over time and space in response to variation water input. In order improve numerical models of glacier hydrology it is important fully understand the processes controlling subglacial system evolution, but contemporary ice sheet beds typically inaccessible. Thus, esker distribution, morphology, sedimentology have been used infer dynamics former sheets. However, debate remains as responsible for formation most theoretical investigations assumed that formed due operated beneath thick despite many field contrary. We investigate during final stages thin, inactive, rapidly decaying Cordilleran Ice Sheet (CIS) interior British Columbia, Canada. A combination geomorphological, ground-penetrating radar (GPR) electrical resistivity tomography (ERT) data suggest ridge sedimentary architecture consistent with synchronous a glacial lake outburst flood (GLOF). These reveal deposition likely took place within an tunnel evacuated late-waning stage flow, following erosion partial fill broader meltwater corridor. Esker reveals this depositional environment was dynamic, reflecting complex interaction between thickness, structure, geometry, flow conditions, sediment supply. Under these inactive conditions location initially governed by structural weaknesses and/or equipotential gradient. Because creep closure rates were low, evolved through feedbacks conduit growth via frictional melting/mechanical excavation, infilling, rather than creep. This resulted non-uniform enlarged upglacier direction locally unroofed form open channels its stages. eskers may record unsteady, flows network so assumptions often made when using inform hydrological components not be applicable all settings.