Paul

I do not know of any oxygen isotope data for the lower depths of the R-L
Ice Shelf - I don't think anyone has drilled through and collected samples
for isotope analysis.  The surface values should be similar to Halley as you
surmise, but those at depth will be considerably more negative since the
ice at depth must have originated from further inland/up-slope in Coats
Land/Dronning Maud Land.  But, again, as you indicate, the flow for this
region is not well known, and you would be guessing if you tried to estimate
the origin and isotope composition of the deep ice.  Incidentally, I am ice
core drilling this year in Dronning Maud Land (at about 77S, 10W) to a
depth of about 120m/1200 years.

----------------------------------------
Dr Robert Mulvaney
Ice and Climate Division
British Antarctic Survey
Madingley Road
Cambridge CB3 0ET
UK
email:  [log in to unmask]
telephone: +44 1223 251400 (switchboard)
telephone: +44 1223 251436 (direct line)
fax:  +44 1223 362616
----------------------------------------


>>> Paul Dennis <[log in to unmask]> 10 Nov 1997  11:49 >>>
Dear all,

I think this may be a long shot but here goes:

I am looking for oxygen isotope data for the Riiser-Larsenisen Ice Shelf on
the Eastern edge of the Weddell Sea at about 72 degrees south. I
anticipate
that the surface compositions will be close to the mean annual isotope
composition of precipitation at Halley Bay at the southern tip of the Brunt
Ice Shelf (76 degrees S). What interests me is does there exist any data
for the base of the interior and base of the shelf. Looking at maps of
Antarctica it is not immediately apparent what the catchment of the shelf
is like, how deep it penetrates into the Antarctic continent, and what age
the ice may be at the base.

To put readers in the picture I have some isotopic data for coastal waters
just off the shelf that indicate that the sea is mixing with a glacial end
member of ca. -30 per mille. I'd like to confirm that this number is
reasonable for this shelf.

Paul

Paul Dennis,
Stable Isotope Laboratory,
School of Environmental Sciences,
University of East Anglia,
Norwich NR4 7TJ