Jökull - 01.12.1974, Síða 52

Fig. 7. Generalized map of the Húsafell central volcano showing the distribution of acid intru-
sions defining the center of the third acid phase. The center of the second acid phase is buried
downdip to the east. Inclined sheets and dykes of basaltic composition ancl a possible caldera
fracture indicate its position.
Mynd 7. Yfirlitskort af Húsafellssvceðinu, sem sýnir dreifingu á liparítinnskotum tilheyrandi
þriðju hrinunni. Basaltceðar og innskot með austlœgum halla og hugsanlegt iiskjubrot vestan við
Kalmanstungu gcetu bent til, að miðsvœði annarrar liparítgoshrinunnar hafi legið i heild heldur
austar.
prehnite and epidote. The rock alteration is
typical of high temperature hydrothermal sys-
tems. Such conditions apparently prevailed in
tlie Húsafell area since the injection of the
second phase basaltic dykes and sheets. The
presence of further basaltic intrusions at depth
underneath the Húsafell central volcano is sug-
gested on a new gravimetric map of Iceland (G.
50 JÖKULL 24. ÁR
Pálmason, personal communication) where a 5—
6 mgal positive gravity anomaly coincides with
its core.
2.3 THE SUCCESSION ABOVE THE
CENTRAL VOLCANO
At the end of the third phase the Húsafell
volcano stood above its surroundings for some