Crynodeb
The geochemical analysis of Arctica islandica shell material from the 1357 year old chronology from the North Icelandic shelf has produced a high resolution, multicentennial record of environmental change. As the shell material is absolutely dated, the chemical or isotopic response in the shells provides detailed and precise evidence about impacts on the marine environment associated with volcanic activity and climatic changes.Using LA-ICP-MS the shell material was analysed for Mg, Sr, Ba, Mn and Fe isotopes. To remove ontogenetic effects data was detrended and standardized to allow comparison with climatic proxies. Principal component analysis was used to examine the results over the periods containing three major volcanic eruptions of Laki Fissure eruption (1783), the Tambora eruption (1815) and the Novarupta eruption (Katmai 1912) to investigate possible effects.
Attempts to identify and define any impacts on the marine environment of the North Icelandic shelf from volcanic eruptions reveal that the size alone of an eruption is not the only influencing factor on the impact, the location of where in the atmosphere the volcanic emissions resided had a major impact. The shell chemistry of Arctica islandica showed little response to the local Laki Fissure eruption and to the Novarupta eruption of Alaska, however there was a larger response to the Tambora eruption, Indonesia.
Using geochemical variations within the shell geochemistry to achor “floating” chronologies via volcanic and major climatic changes has proved unsuccessful. This is due to a lack of clear response to volcanic inputs and the variable and inconsistent concentrations of elements analysed combined with the complex climatic and oceanic system occurring off the North Icelandic Shelf. The use of Mg variations however has potentially proved successful in temporally aligning an undated section of shell, and thus “anchoring” and dating it.
| Dyddiad Dyfarnu | 2019 |
|---|---|
| Iaith wreiddiol | Saesneg |
| Sefydliad Dyfarnu |
|
| Goruchwyliwr | Nick Pearce (Goruchwylydd), Bill Perkins (Goruchwylydd) & Paul Butler (Goruchwylydd) |