A stacked mixing sequence at the base of the Dye 3 core, Greenland.

Geophysical Research Letters, Vol. 25, No. 11, p. 1943-1946, 1998

R. Souchez, A. Bouzette
Département des Sciences de la Terre et de l'Environnement, Faculté des Sciences, Université de Bruxelles, Bruxelles, Belgium.
H.B. Clausen and S.J. Johnsen
Departement of Geophysics, The Niels Bohr Institute of Astronomy, Physics and Geophysics, University of Copenhagen..
J. Jouzel
Laboratoire de Modélisation du Climat et de l'Environnement , Gif-Sur-Yvette, France.

This paper documents, by a detailed isotopic and gas composition study of the basal ice from the Dye 3 core, a large degree of flow-induced mixing at the ice sheet base. This mixing results most probably from circular motion in troughs of bedrock undulations and flow separations with some entrainment of the underlying ice. The measured distribution of isotopes and gases in the basal ice is the consequence of successive mixing events having occurred upglacier from the site in an area of very rough bedrock topography. The deformation produced makes it possible for the basal part of the ice sheet to cross the subglacial valley existing in the Dye 3 area.