Investigating processes of marine ice formation in a floating ice tongue by a high-resolution isotopic study

R. Souchez (1) , J.-L. Tison (1) , R. Lorrain (1) , C. Fléhoc , M. Stiévenard (2) , J. Jouzel (2) , V. Maggi (3)

1 ULB - Université libre de Bruxelles
2 LMCE - Laboratoire de Modélisation du Climat et de l'Environnement
3 UNIMI - Università degli Studi di Milano = University of Milan

A better knowledge of boundary conditions near a grounding line is critical for understanding the behavior of ice shelves and floating glaciers. We show here that significant information can be gained from a high-resolution isotopic and textural study of marine ice accreted at the bottom of a floating glacier near its grounding line. Two different types of marine ice have been found. Type 1 is bubble-and debris-free ice with properties which, we believe, can be explained by intrusion of brackish water in open basal fissures. Closing of the fissures by progression of a freezing front from the sides is precluded, and filling by frazil ice is favored. Type 2 is made of thin, clear ice and debris layers which are thought to have formed when a subglacial water-filled sediment enters into contact with seawater and is subjected to freezing under a doublediffusion process. The paper also stresses that in a •iD-•i•80 diagram the alignment of marine ice samples on a mixing line does not necessarily imply a mixture of continental water and seawater in varying proportions.

Domaines: Glaciologie; Océanographie

R. Souchez, J.-L. Tison, R. Lorrain, C. Fléhoc, M. Stiévenard, et al.. Investigating processes of marine ice formation in a floating ice tongue by a high-resolution isotopic study. Journal of Geophysical Research. Oceans, 1995, 100 (C4), pp.7019-7025. ⟨10.1029/95JC00142⟩. ⟨hal-03334866⟩