High‐resolution stratigraphy of the northernmost concentric raised bog in Europe: Sellevollmyra, Andøya, northern Norway

Abstract

From the Sellevollmyra bog at Andøya, northern Norway, a 440‐cm long peat core covering the last c. 7000 calendar years was examined for humification, loss‐on‐ignition, microfossils, macrofossils and tephra. The age model was based on a Bayesian wiggle‐match of 35 14C dates and two historically anchored tephra layers. Based on changes in lithology and biostratigraphical climate proxies, several climatic changes were identified (periods of the most fundamental changes in italics): 6410–6380, 6230–6050, 5730–5640, 5470–5430, 5340–5310, 5270–5100, 4790–4710, 4890–4820, 4380–4320, 4220–4120, 4000–3810, 3610–3580, 3370–3340 (regionally 2850–2750; in Sellevollmyra a hiatus between 2960–2520), 2330–2220, 1950, 1530–1450, 1150–840, 730? and c. 600? cal. yr BP. Most of these climate changes are known from other investigations of different palaeoclimate proxies in northern and middle Europe. Some volcanic eruptions seemingly coincide with vegetation changes recorded in the peat, e.g. about 5760 cal. yr BP; however, the known climatic deterioration at the time of the Hekla‐4 tephra layer started some decades before the eruption event.

An overview of distal tephrochronology in northern Europe during the last 1000 years

“…Hall and Pilcher, 2002). According to proximal deposits, however, the main transport component of this eruption was to the north and northeast (Thorarinsson, 1967;Larsen et al, 1999), yet Hekla-1 has only been identified in two distal sites in northern Norway and within marine records off the Icelandic coast (Larsen et al, 2002;Pilcher et al, 2005;Kristjansdó ttir et al, 2007;Vorren et al, 2007). This may be a feature of where tephra investigations over the last 1000 a have been conducted in recent years rather than a real absence of Hekla-1 tephra.…”

“…Hekla-1 is one of the most widespread Holocene tephras from Iceland and was reported in Scandinavian peat bogs as early as the 1960s (Persson, 1966). Persson's records were not confirmed by geochemical analyses, however, and it was not until recently that the Hekla-1 was securely identified in sequences in Scandinavia (Pilcher et al, 2005;Vorren et al, 2007). This tephra is also the most reported historic tephra in Ireland (Pilcher et al, 1996;Hall and Pilcher, 2002;Chambers et al, 2004), and has been used to constrain timeframes for climate and human impact studies of Irish bogs (Hall, 2003;Hall and Mauquoy, 2005).…”

“…Ireland is probably the most studied area with regard to distal tephrochronology in Europe, but recent investigations show the potential for similar studies also in Scandinavia (e.g. Bergman et al, 2004;Boygle, 2004;Pilcher et al, 2005;Davies et al, 2007;Vorren et al, 2007;Borgmark and Wastegård, 2008). For instance, historically dated distal tephras from the last millennium have been used to constrain age-depth models and for validation of other dating methods, e.g.…”

“…The AD 1104 event was the largest Hekla eruption in historical times (Thorarinsson, 1967) and the associated tephra layer is one of the most important isochrones in terrestrial and marine records on Iceland (Larsen and Thorarinsson, 1977;Boygle, 1999;Larsen et al, 1999Larsen et al, , 2002 and more distal sites in Europe (Pilcher et al, 1996(Pilcher et al, , 2005Chambers et al, 2004;Vorren et al, 2007). This tephra can be separated from other historical Hekla tephras in plots of K 2 O/TiO 2 ( Fig.…”

“…The grey field in (b) shows the distribution of FeO tot versus TiO 2 in SILK tephra layers from Iceland and the Faroe Islands (Larsen et al, 2001;Wastegård, 2002;Ó ladó ttir et al, 2008). Data points are from the following sources: MOR-T4 (Chambers et al, 2004); Hekla-1 (Pilcher et al, 1995(Pilcher et al, , 1996(Pilcher et al, , 2005Hall and Pilcher, 2002;Chambers et al, 2004;Vorren et al, 2007); BGMT-1 (Langdon and Barber, 2001); Hekla-1158 (Hall and Pilcher, 2002;Pilcher et al, 2005); GB4-50 (Hall and Pilcher, 2002); Ö raefajö kull-1362 (Pilcher et al, 1995(Pilcher et al, , 2005Hall and Pilcher, 2002); MOR-T2 (Chambers et al, 2004); Veiðivö tn-1477 (Chambers et al, 2004;Davies et al, 2007); Hekla-1510 (Dugmore et al, 1995;Pilcher et al, 1996;Swindles, 2006); Loch Portain B (Dugmore et al, 1995); SLU-5 (Hall and Pilcher, 2002); QUB-384 (Pilcher et al, 2005); PMG-5 (Hall and Pilcher, 2002); Hekla-1845 (Wastegård, 2002); Askja-1875 (Oldfield et al, 1997;Boygle, 2004;Bergman et al, 2004;Davies et al, 2007;Borgmark and Wastegård, 2008); Hekla-1947 (Hall andPilcher, 2002;Swindles, 2006) Icelandic eruption during the early Medieval period. MOR-T4 and GB4-50 have similar geochemical signatures, but GB4-50 is considerably higher in FeO tot …”