Jökull - 01.01.2017, Page 37

Svavarsdóttir et al.
Figure 7. Geological map of Holocene lavas the Bárðardalur region showing sample location and their division
into different units. Modified map from Sigurgeirsson et al. (2015). – Kort sem sýnir skiptingu hrauneininga
Bárðardals.
Bárðardalur – Bárðarbunga tephra
The petrographical similarity of the lavas found in
Bárðardalur, especially Kinnarhraun and Bárðardals-
hraun lavas, and Bárðarbunga volcanic products has
been pointed out by many researchers (e.g., Sigbjarn-
arson, 1988; Vilmundardóttir and Kaldal, 1991; Hjart-
arson, 2004). In terms of petrochemistry, we note the
good agreement between the field for Bárðarbunga
tephra samples and analyses of the Frambruni lava,
whereas a few samples from Bárðardalshraun (Bár-
1) and Kinnarhraun lava fall outside the Bárðarbunga
tephra field (Figures 8c and 8d). However, the Bár-2
samples fall within the primitive end of the compo-
sitional field of the Bárðarbunga tephra. Despite the
fact that most Kinnarhraun and Bárðardalshraun sam-
ples are more primitive than the Bárðarbunga tephra
field, we note that all these samples tend to follow the
same trend outlining a possible liquid line of decent
for the Bárðarbunga system. This is consistent with
an association of the Bárðardalur lavas with the Bárð-
arbunga volcanic system.
32 JÖKULL No. 67, 2017