The oxygen-18 isotope profile of the Dome Fuji ice core from Antarctica suggests that the age of the deeper part of the core corresponds to Marine Isotope Stage 17 (about 720,000 years before present).

http://polaris.nipr.ac.jp/~domef/icc-home/ICC-pub-files/2007/07KOPRI-uemura.pdf

The surface ice movement rate at Dome Fuji is less than several centimeters per year, and you can read about the ways that glaciologists determine such flow rates here:

http://www.clim-past-discuss.net/3/19/2007/cpd-3-19-2007.pdf

Where's your evidence that these glaciers can't possibly be so old?

Also, where exactly did you learn about hydrothermal vents and their relationship to glaciers? Last I knew, hydrothermal vents weren't clustered around glacial areas, but you're welcome to enlighten me.