Jökull - 01.01.2012, Side 26

B. A. Óladóttir et al.
tion, often augmented by interaction with water, sili-
cic eruptions develop higher eruption plumes and the
tephra can be transported further away from source.
Hence, the silicic tephra layers are good tephra marker
layers, both on a local and regional scale, and, thus,
form the cornerstones of Icelandic tephrostratigraphy
and tephrochronology (Table 1, Figure 2).
Table 1. Widely used tephra marker layers, their composition, age, size indicator and strike of main thickness
axes. – Algeng gjóskuleiðarlög, efnasamsetning, aldur, stærðarmat og stefna þykktaráss.
Tephra Volcanic Com- 14C Calibrated 2s/ Volume Strike of main Reference
marker system posi- dates calender yrs1 (km3) thickness axes
layer tion◦
K-1918 Katla B 1918 AD <1 North-northeast Thorarinsson, 1975; Larsen, 2010
K-1755 Katla B 1755 AD ∼1 East, southeast Thorarinsson, 1975; Larsen, 2010
K-1721 Katla B 1721 AD <1 West, northwest Thorarinsson, 1955; Larsen, 2010
K-1625 Katla B 1625 AD <1 East, southeast Thorarinsson, 1981, Larsen, 2010
V-1477 Bárdarbunga B 1477 AD >1 East, northeast Larsen, 1984, Larsen, 2005
Ö-1362 Öræfajökull S 1362 AD >1 South, southeast Thorarinsson, 1958
H-1300 Hekla I 1300 AD <1 North Thorarinsson, 1967; Larsen et al., 1999
K-1262 Katla B 1262 AD <1 Northeast Larsen, 2010
H-1206 Hekla I 1206 AD <1 Southeast Thorarinsson, 1967; Larsen et al., 1999
H-1158 Hekla S 1158 AD <1 Northeast Thorarinsson 1967; Larsen et al., 1999
H-1104 Hekla S 1104 AD >1 North Thorarinsson, 1967; Larsen et al., 1999
Eldgjá Katla B 934 AD >1 South, southeast Hammer et al., 1980, Larsen, 2000, 2010
V-870 (LNL) Bárdarbunga B+S 871 AD >1 Northwest Larsen, 1984; Grönvold et al., 1995
Hrafnkatla Katla B *760 AD Northeast Óladóttir et al., 2011a
YN Katla S 1676±12 BP 380 AD <1 Northwest Larsen et al., 2001
Sn-1 Snæfellsjökull S 1750±150 BP 325 AD North, northeast Steinthorsson, 1967;
Jóhannesson et al., 1981
Grákolla (G) Torfajökull S 1995±30 10 AD Northeast Larsen and Eiríksson, unpubl. data
Askja (A) Askja S 1995±30 10 AD South, southeast Same age as Grákolla**
Hx Hekla I *280 BC <1 East, northeast Larsen and Vilmundardóttir, 1992;
Óladóttir et al., 2011a
HA Hekla I+S 2450±55 580 BC <1 West Róbertsd., 1992a; Róbertsd. et al., 2002a;
Sigurgeirsson and Sveinbjörnsdóttir, 1999
Hy Hekla I *600 BC <1 East Larsen and Vilm.d., 1992; Ólad. et al., 2011a
Hz Hekla I *720 BC <1 Northeast Larsen and Vilm.d., 1992; Ólad. et al., 2011a
HB Hekla I+S <1 West Róbertsdóttir, 1992a
UN Katla S 2660±50 BP 850 BC <1 East, northeast Larsen et al., 2001
HC Hekla I+S 2660±80 BP 850 BC Northwest Thorarinsson, 1964; Róbertsdóttir, 1992a
HM Hekla I+S *960 BC <1 Southeast Larsen et al., 2002b; Ólad. et al., unp. data
HN Hekla I+S *1030 BC <1 Southeast Larsen et al., 2002b; Ólad. et al., unp. data
K-E Katla B >1 Northwest Róbertsdóttir, 1992b
H3 Hekla I+S 2879±34 BP 1050 BC >1 North Dugmore et al., 1995b;
Larsen and Thorarinsson, 1977
MN Katla S 2975±12 BP 1210 BC <1 South-southeast Larsen et al., 2001
LN Katla S 3139±40 BP 1430 BC <1 Northeast Larsen et al., 2001
K-N Katla B >1 West-southwest Róbertsdóttir, 1992b
HS Hekla I+S 3515±55 BP 1855 BC >1 East, southeast Larsen et al., 2001; Larsen et al., 2012
N4 Katla S ∼3600 ∼2000 BC <1 Northwest Larsen et al., 2001
H4 Hekla I+S 3826±12 BP 2250 BC >1 North, northeast Dugmore et al., 1995b;
Larsen and Thorarinsson, 1977
Sn-2 Snæfellsjökull S 3960±100 2450 BC North, northeast Steinthorss., 1967; Jóhanness. et al.,1981
HÖ Hekla I+S 5275±55 BP 4110 BC ∼1 Northeast Gudmundsdóttir et al., 2011
H-DH Hekla B+I *4650 BC <1 North-northeast Gudmundsdóttir et al., 2011
H5 Hekla S 6185±90 BP 5120 BC >1 North Thorarinsson, 1971;
Larsen and Thorarinsson, 1977
A13 Torfajökull S 7505±42BP ∼6380 BC Southeast Larsen et al., 2001; Óladóttir et al., 2008
◦B (basaltic) <52wt% SiO2. I (intermediate) 52–63wt% SiO2. S (silicic) >63wt% SiO2 1Mean calendar age, calibrated after Stuiver et
al., 1998. *Calculated soil accumulation rate age. **Grákolla and Askja marker layers are present as separate layers in some profiles, but
where their distribution overlaps they occur as a single layer consisting of a mixture of the two. This close proximity stratigraphically
suggests a near synchronous deposition of these layers and therefore they have been allocated the same age.
24 JÖKULL No. 62, 2012