Jökull - 01.01.2014, Side 52

J. Helgason and R. Duncan
Figure 8. Correlation of the observed magnetostratigraphy from Hafrafell with the geomagnetic polarity time
scale (Gradstein et al., 2012). – Tenging bergsegulstefnu Hafrafells við segultímatal.
Table 2. K-Ar ages for selected stratigraphic units in Hafrafell. – Niðurstöður aldursgreininga fyrir jarðlög
Hafrafells.
Sample Coordinates Stratigraphic Total fusion age %K %Ar Elevation Formation
no. height (m) ±2sd (Ma) rad. rad. m a.s.l.
HV N64◦0’32.76" W16◦52’28.92" 2720 0.21±0.01 0.540 9.0 280 HF39
T22 N64◦1’66.67" W16◦51’59.03" 1496 1.69±0.29 0.158 2.8 616 HF31
HZ N64◦0’47.51" W16◦52’7.68" 478 2.35±0.22 0.232 1.2 435 HF14
HL27 N64◦0’42.83" W16◦52’26.75" 298 3.20±0.09 0.299 12.5 340 HF8
HL1 N64◦0’41.03" W16◦52’48.71" 5 3.92±0.06 0.411 52.1 132 HF1
Ages calculated with the following decay and abundance constants: λε = 0.580×10−10 yr−1; λ = 5.463×10−10 yr−1;
40K/K = 1.17×10−4.
Landscape evolution of SE Iceland
An intriguing question is how has the landscape of
Iceland evolved from Neogene subaerial volcanism
through some 20 glacials to a currently mountainous
terrain with glaciers and deep valleys? Several studies
have focused on the timing and frequency of glacia-
tions in Iceland (e.g. Geirsdóttir, 2011). The timing
of early valley formation and stratigraphic hiatuses
presented in the current study may add details to this
subject although it may remain speculative to what
extent landscape evolution of SE Iceland has reflected
52 JÖKULL No. 64, 2014