Simon A. Larsson
This dataset contains results from extractions of distal tephra (far-travelled volcanic ash) and from major-element geochemistry analyses of what was identified as two previously known tephras, the Fosen Tephra and the Vedde Ash, from three sampling sites on the Fosen peninsula in central Norway — the Lomtjønnmyran fen, the Damåsmyran bog, and lake Rørtjønna.
The Vedde Ash (c. 12,000 years old; 12 ka) is a well-used tephra isochron in chronological and palaeoclimatological studies of the Last Glacial-Interglacial Transition and commonly marks the Younger Dryas stadial (Greenland Stadial 1) in the accumulations wherein it is identified. The more recently discovered Fosen Tephra (c. 10.2 ka) in turn marks the early Holocene, and thus is useful to confirm the timing of the transition into the warmer climate of this epoch.
The sample material was collected in the field in May 2017 in the form of sediment cores by use of Russian corers. Tephra extractions were performed during the fall of 2017 and spring of 2018. Tephra shard concentration estimates were calculated for the Lomtjønnmyran and Damåsmyran sites by comparing tephra counts with counts of Lycopodium spores from added tablets of known spore amounts. Geochemical analyses were performed in April and December 2018.
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Citation
Simon A. Larsson (2021) Stratigraphy and geochemistry of the Fosen Tephra and the Vedde Ash at three sites on the Fosen peninsula, central Norway. Dataset version 1. Bolin Centre Database. https://doi.org/10.17043/larsson-2021-fosen-vedde-1
References
Dugmore AJ, Larsen G, Newton AJ (1995) Seven tephra isochrones in Scotland. The Holocene 5:257 – 266. https://doi.org/10.1177/095968369500500301
Hayward C (2012) High spatial resolution electron probe microanalysis of tephras and melt inclusions without beam-induced chemical modification. The Holocene 22:119 – 125. https://doi.org/10.1177/0959683611409777
Høgaas F, Larsson SA, Klug M, Olsen L, Wastegård S (2021) Palaeolake sediment records reveal a mid- to late Younger Dryas ice sheet maximum in Mid-Norway. Manuscript in preparation
Jowsey PC (1966) An improved peat sampler. New Phytologist 65:245 – 248. https://doi.org/10.1111/j.1469-8137.1966.tb06356.x
Lind EM, Wastegård S, Larsen JJ (2013) A Late Younger Dryas–Early Holocene tephrostratigraphy for Fosen, Central Norway. Journal of Quaternary Science 28:803 – 811. https://doi.org/10.1002/jqs.2676
Mangerud J, Lie SE, Furnes H, Kristiansen IL, Lømo L (1984) A Younger Dryas Ash Bed in Western Norway, and Its Possible Correlations with Tephra in Cores from the Norwegian Sea and the North Atlantic. Quaternary Research 21:85 – 104. https://doi.org/10.1016/0033-5894(84)90092-9
Turney CSM (1998) Extraction of rhyolitic component of Vedde microtephra from minerogenic lake sediments. Journal of Paleolimnology 19:199 – 206. https://doi.org/10.1023/A:1007926322026
Data description
The dataset consists of six tables and is provided as an Excel spreadsheet (.xlsx) of individual tabs for each table, and as comma-separated values files (.csv), one for each table (character set: Western Europe, ISO-8859-15/EURO). There is also a tab/file titled "readme" that contains a basic summary and the table legends, which are also provided here.
Table 1. Tephra extraction results from Lomtjønnmyran with estimated tephra estimations at selected levels presented as shards cm⁻³ wet sediments.
Table 2. Tephra extraction results from Damåsmyran, with estimated tephra estimations at selected levels presented as shards cm⁻³ wet sediments.
Table 3. Tephra extraction results from Rørtjønna.
Table 4. Major-element oxide compositions of the Fosen Tephra at sites Lomtjønnmyran (sample LM593-594) and Damåsmyran (sample DM346-347) presented as oxide weight percentages and normalised to 100 % totals.
Table 5. Major-element oxide compositions of the Vedde Ash at sites Lomtjønnmyran (sample LM722-727) Damåsmyran (sample DM368-369) and Rørtjønna (sample RT5040-5045) presented as oxide weight percentages and normalised to 100 % totals.
Table 6. Secondary glass standard analysis results from the geochemical analysis sessions used for control and calibration.
Comments
The research for which this dataset was created was carried out by Simon A. Larsson under the supervision of Stefan Wastegård in the years 2017 – 2021 and contributed to a new interpretation of the timing of the deglaciation on the Fosen peninsula during the Younger Dryas (Høgaas et al. 2021, in prep.).
The collection of the sample material and the analyses performed for the production of this dataset was done with the aid of Fredrik Høgaas, Helene Sunmark, and Chris Hayward.
Please, cite the appropriate articles when using this dataset.
Tephras analysed
- Fosen Tephra (Lind et al. 2013)
- Vedde Ash (Mangerud et al. 1984)
Site locations
- Lomtjønnmyran fen (63° 40’ 17.7” N, 10° 32’ 49.5” E)
- Damåsmyran bog (63° 47’ 59.2” N, 10° 48’ 32.3” E)
- Lake Rørtjønna (63° 39’ 33” N, 10° 32’ 02” E)
Sampling and measurement methods
The sample material for this research was collected in the form of sediment cores by use of Russian corers (Jowsey 1966). Tephra extractions were performed following slightly modified methods of Turney (1998) for initial extractions and Dugmore et al. (1995) for extractions for geochemical analysis. Tephra shard concentration estimates were calculated for the Lomtjønnmyran and Damåsmyran sites by comparing tephra counts with counts of Lycopodium spores from added tablets of known spore amounts. Geochemical analyses were performed using a Cameca SX100 electron probe microanalyser (a.k.a. EPMA) at the University of Edinburgh, Scotland (Hayward 2012). Glass standards Lipari and BCR-2G were used for control and calibration during the analysis sessions.