Friday, 31 August 2007
5.PS-138
Investigating the bedrock topography effect on the ice flow ablation using analogue modelling technique
Giacomo Corti1, Antonio Zeoli2, Pietro Belmaggio3, and Luigi Folco2. (1) CNR-Istituto di Geoscienze e Georisorse, Firenze, Italy, (2) Museo Nazionale Antartide, via Laterino 8, Siena, Italy, (3) Dipartimento di Scienze della Terra,, Università di Firenze,, via la Pira 4, Firenze
Three-dimensional laboratory physical experiments have been used to investigate the influence of bedrock topography and ablation on ice flow. Different models were tested in a Plexiglas box, where a transparent silicone simulating ice in nature was allowed to flow. Experimental results show how the flow field and variations in the topography of the free surface and internal layers of the ice are strongly influenced by the presence and height of bedrock obstacles. In particular, the buttressing effect forces the ice to slow down, rise up and avoid the obstacle; the higher the bedrock barrier, the more pronounced the process. In order to exhume deep material embedded in the ice, ablation must be included in the physical models. In this case, the analogue ice replenishes the area of material removal, thereby allowing deep layers to move vertically to the surface and severely altering the local ice flow pattern.