Jökull - 01.12.1970, Qupperneq 3

ihV.íT
M
JÖKULL
Á R S R I T
JÖ KLARAN NSÓ K N AFÉLAGS ÍSLANDS
20. ÁR REYKJAVÍK 1970
Rannsóknir á Bárðarbungu 1969 og 1970
PÁLL THEODÓRSSON,
RAUNVÍSINDASTOFNUN HASKOLANS
ABSTRACT
Deuterium and, Tritium in Ice Cores
from Bárdarbunga on Vatnajökull
The isotopic composition of an ice core taken
through the Greenland ice sheet has given valu-
a,ble information about past climatic changes.
Glaciers in Iceland might preserve a similar
record. The record could be destroyed by melt-
water in a temperate glacier. The northwestern
part of the Vatnajökull glacier (Bárdarbunga,
altitude 2000 meters) would be most likely of
all glaciers in Iceland to preserve the original
isotopic composition. The airticle describes the
preliminary work that has been catrried out on
Bárdarbunga in 1969 and 1970 as a prepara-
tion for drilling through the ice cap, mainly
in order to obtain information about climatic
changes in Iceland.
The main points of the work reported are the
following.
1) Samples of ice doxon to a depth of 27 met-
ers have been taken by digging a 10 m deep
pit and by drilling a 17 m deep hole from the
bottom of the pit xuith a mechanical drill.
Deuterium (Árnason 1970) and tritium measure-
LAMDE
3 0
ments show that there is little isotopic exchange
between the ice and meltwater.
2) A 108 xn deep h.ole has been drilled wilh a
thermal drill. This drill, however, melts the
core partly a,nd often no core was recovered at
all. Deuterium (Arnason 1970) and tritium in
this core have been measured, and the results
of the tritum measurements are given in the
article.
3) Temperature measurements show that
Bárdarbunga is a temperate glacier, in spile of
an estimated mean annual temperature of
-6° C.
4) Valuable experience has been gained in
drilling with a mechanical and thermal drill.
9) Txuo ash layers xuere found in the 108 rn
deep borehole, at a depth of 80 m and 101 m.
These are from volcanic eruptions in Iceland
in 1934 and 1918. Very thin ash layers are
easily detected in the clear ice.
6) The thickness of the ice cap at Bárdar-
bunga has been estimated from gravimetry.
As a result of this work it is noxu planned
to drill through the ice cap of Bárdarbunga in
1972. ,
'
-DOKAoAFfl j JÖKULL 20. ÁR ]
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ISLANDS