Jökull - 01.01.2010, Page 111

The Kerlingar fault, Northeast Iceland
Figure 8. A segment of the Kerlingar fault. View towards the north. – Hluti af Kerlingamisgenginu. Horft til
norðurs.
The Kerlingar fault – a Holocene feature
Several faults are found outside or at the margins
of the NVZ in the Dimmifjallgarður area (Figure 3).
The majority of them have been assumed to be pre-
Holocene because of their eroded appearance and
large distance from the axis of the rift zone. A no-
table exception is the Kerlingar fault. It has a sharp
topographic expression and can be traced on satel-
lite images for tens of kilometers with few interrup-
tions. Our field investigation revealed a sharp step
in a moraine, delineating a part of the fault (Figures
8 and 9). This indicates that the Kerlingar fault has
been active at some time during the Holocene, as a
glacier would have eroded this feature if it was older.
It is unlikely that drainage of a snow melt would cause
the sharp step in the moraine, as the moraine is for
the most part not located in a slope, where meltwa-
ter could carry away sediments from the fault scarp.
Holocene activity of other faults in the Dimmifjall-
garður area cannot be excluded, but this needs to be
investigated further. As discussed before, the Kerl-
ingar fault is parallel with the NVZ-EFB boundary,
and is not perpendicular to the plate spreading vector
(DeMets et al. 1994). Normal faults, such as the Kerl-
ingar fault, are stress indicators, i.e. probably have a
strike perpendicular to the least principal stress axis.
The Holocene activity of the fault therefore indicates
that it is either formed before a change occurred in the
crustal stress field at the beginning of the Holocene, or
it is related to processes unrelated to the plate move-
ments that generate the present crustal stress field.
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