SEDIMENTARY ARCHITECTURE AND GEOMORPHOLOGY OF GLACIAL DEPOSITS WITHIN A VALLEY GLACIER LANDSYSTEM, SOLHEIMAJOKULL, SOUTHERN ICELAND

Groundwater investigators working in areas of previously-glaciated terrain are faced with the challenge of understanding highly complex glacial deposits based primarily on one-dimensional borehole data. In order to better understand these complex systems and to construct accurate hydrostratigraphic models it is essential to determine the stratigraphic and spatial distribution of glacial and proglacial sediments in modern analogue sites with two- and three-dimensional outcrop control. This poster presents a detailed sedimentological and geomorphological investigation of outcrop exposures and landforms in the proglacial area of Solheimajokull outlet glacier in southern Iceland.

The proglacial area of Solheimajokull contains easily accessible and well-developed landforms and sediment exposures in ice-contact and distal proglacial areas, and in several glaciofluvially-incised terraces. Facies types, including tills, glaciolacustrine silts and clays, and glaciofluvial sands and gravels were identified and logged, and facies geometries were delineated on photomosaics of well-exposed outcrop faces. Landforms, terraces and surficial sediments were mapped using a handheld Garmin GPS instrument. Sediments and landforms at Solheimajokull record multiple late Quaternary ice advances, which deposited thin till sheets, followed by periods of ice retreat, characterized by glaciofluvial incision and deposition of coarse-grained sediment.

The Solheimajokull landsystem contains a high degree of sedimentary and geomorphologic heterogeneity at various scales and geometric complexity. Multiple incision events generated by glaciofluvial systems have dissected previously deposited till sheets and glaciofluvial sediments to create significant hydraulic connections between coarse-grained units that were likely hydraulically isolated prior to incision. The sedimentologic and geomorphologic features identified at Solheimajokull can be used as a modern analogue for previously glaciated areas in which glaciofluvial/ fluvial systems have incised and punctured regional aquitards. Complex glacial stratigraphies similar to those at Solheimajokull host productive aquifers in many areas of southern Ontario, Canada.