Jökull - 01.01.2012, Side 64

E. R. Guðmundsdóttir et al.
Table 2. Holocene tephra layers in marine sediments on the Iceland shelf cont. – framhald.
Age Volc. Tephra 1-6 7 8-11 12 13 14 15 16 17 18-19 20 21 22 23 24 25 26 27 28 29-30 31 32
(cal.) syst. markers
(BP)
8000 Katla Suduroy X X
8243 Grímsvötn X
8200 Grímsvötn X
8394 Eyjaf.j. X
8400 Katla X
8485 Grímsvötn X
9909 Grímsvötn X
10055 Grímsvötn X
10218 Grímsvötn X
10300 Grímsvötn Saks.vatn X X X X X X X X X X X X X
10319 TFZ or KOL X
10334 TFZ or KOL X
10422 Vei-Bár X
10457 Vei-Bár X
10620 TFZ or KOL X
10650 TFZ or KOL X X
10764 Vei-Bár X
11000 Askja Askja-S X
11058 TFZ or KOL X X
11107 TFZ or KOL X X
12045 Vei-Bár X
12120 Katla Vedde Ash X X X X X X X X X X
12165 Vei-Bár X
12210 Katla X
12600 Katla X
12667 Grímsvötn X
12999 Vei-Bár X
13429 TFZ or KOL X
13600 Katla X
14000 Katla X
14389 Vei-Bár X
14360 KOL X X
14550 Unknown Borrobol X X X X X
14600 Grímsvötn X X
15000 Grímsvötn X X
1. MD99-2256; 2. MD99-2266; 3. B997-315; 4. MD99-2265; 5. B997-337; 6. B997-336; 7. MD99-2264; 8. B997-330; 9. B997-329; 10. B997-332; 11.
B997-325; 12. B997-323; 13. MD99-2269; 14. B997-322; 15. HM107-04; 16. MD99-2271; 17. HM107-03; 18. MD99-2273; 19. *B05-2006-MC03; 20.
B997-317; 21. HM107-01; 22. B997-319GGC; 23. B997-319; 24. BB97-316; 25. B997-320; 26. B997-321; 27. MD99-2272; 28. HM107-05; 29.
MD99-2275; 30. *B05-2006-MC04; 31. RAPiD-10-1P; 32. RAPiD-15-4P. Cores in bold are longer than 10 m and cores with asterisk are multi-cores,
spanning approximately the last 150 years. For core locations see Figure 1.
RAPiD cores are outside the shelf but are neverthe-
less included here to give a better overview. Table 2
shows the number of tephra layers identified on dif-
ferent parts of the Iceland shelf.
North Iceland shelf
On the North Iceland shelf there are evidence of sedi-
ments containing tephra layers as old as about 50,000
years (Haraldsson, 2004; Telesinski, 2010).
The majority of sediment cores are located on the
North Iceland shelf (Figure 1) which was targeted for
coring because of high sedimentation rates and con-
vergence of cold and warm air- and water masses
in the area, which make it very sensitive to climate
change and thus an interesting area to study oceano-
graphic and atmospheric changes. As a consequence
the greatest number of tephra layers have been found
on the North Iceland shelf (e.g. Eiríksson et al., 2000,
2004, 2011; Larsen et al., 2002; Kristjánsdóttir et
al., 2007; Knudsen et al., 2004, 2008; Gudmunds-
dóttir et al., 2011a, 2011b, 2012) (Table 2) because
the density of available cores varies between regions
and tephra layers in other cores have not been ana-
lysed in the same detail as core MD99-2275 (Table
2, Figures 1 and 3). Core MD99-2275 has the most
reported tephra layers, over 100, so far (Søndergaard,
2005; Gudmundsdóttir et al., 2012).
62 JÖKULL No. 62, 2012