Jökull - 01.12.1967, Side 67

Fig. 1. The geological section of the
well in Vestmann Islands (ol: olvine,
py: pyroxene, py-hr: pyroxene with
hourglass structure).
Mynd 1. Jarðlagasnið af holunni i Vest-
mannaeyjum.
Depth Dýpi m Explanation of the geological column Skýringar viO jarðtagasniðið MofiC phenocrysts Dökkir feno kristollar An content of plagioclose Depth Dýpi
Vestraísi. -formation Vestm.eyja 'Z-'T.rV.r Basaltic sond layers interbedded with tuff or basalt Fjögur sand/ög aðskiiin með tuffi eða basa/ti

- 100 Basaltic tuff Túff Tillite Jökuiberg Bosaltic tuff Túff ol 60-70 100 -j
-myndun ol 70
- 200- Tillite Jökuiberg - 200-
- 300- Sediment - ary ++± + - Diobase sili tnnskot Sondstone Sondsteinn Sandstone Sandsteinn py + ol 50-64 - 300-
formation —-■-
Set- —-1T1T-
Sandstone Sandsteinn
-400- myndun —-_TTT - 400-
-ET-£r£? Sediment varying in groin size and content of tuffaceous moleriol mostly marine sediments
- 500 — Misgróft og mistúffrikt set, mest sjávarset :500:

-600- Tillite Jökutberg
+ + + + k+ + + + + + + + Diabase sill tnnskot Tillite Jökuiberg py + ol 50-64
py-hr 55 -700-
Sandstone Sandsteinn Basolt Basait

Sandstone Sandsteinn Volcanic breccía Móberg py-hr 64
- 800- -zj-zs-jr Fine grained sediment Fint set -800-

64

- 900- Basolt formation 'l'i' III Tholeiitic basalt with partings Þóleitiskf boso/f með miHHögum py-hr 64 -900-

-1000-; myndun |l|l| py-hr 64 1000-j

lli Basalt layers without partings Basaittög án millilaga py ol py
rll00 ■ II 70 -1100-
60
11111 70
III py-hr py -1200-

| l 1 I 1 I 1 py 70 -1300-
70-75
11111 Basalt layers with portings Basatt/ög með millilögum Fine grained sediment Fint set py py 60-70 60-64
-1400- 3-Z-I-I -1400-
11111 Basalt layers with partings Basatt/ög með miililögum py 64
tnr ol + py 60-70
-1500- tTt{t py 64 -1500-
111 py + ol 50-64

1565-^ '11111 —py— ao
HYDROLOGY
Drilling of deep wells in Iceland (deeper
than 100—200 m) like that in the Vestmann
Islands is carried out witli the use of a rotary
drill. Water is pumped through the drillpipes
bringing up chippings outside the drillpipes.
If a water-yielding-layer is struck, the water
pumped down is lost in proportion to the abi-
lity of the layer to yield water again. A con-
siderable loss of water is reported to have
ocurred at a depth of approx. 820 m (0.2 1/s)
i.e. on the boundary between the basalt forma-
tion and the marine sediments. The loss of
water increased to a depth of 900 m, when it
was 0.5 1/s.
Three pumping tests have been performed.
The first was carried out in the period April
28 to May 4, 1964 after the well had reached
a depth of 900 m. After the drilling had been
completed on September 15, 1964 two further
tests were made in September 17—19, 1964 and
October 18 to November 1, 1965.
The result of the first pumping test is shown
in Fig. 2. Water level, discharge rate and tem-
perature of the water have been plotted against
time. At the end of the pumping test the
water level was 13 m, the discharge rate 0.7—
JÖKULL 17. ÁR 301