Smoking guns and volcanic ash: the importance of sparse tephras in Greenland ice cores

Plunkett, Gill; Sigl, Michael; Pilcher, Jonathan R.; McConnell, Joseph R.; Chellman, Nathan; Steffensen, J.P.; Büntgen, Ulf (2020). Smoking guns and volcanic ash: the importance of sparse tephras in Greenland ice cores. Polar research, 39 Norwegian Polar Institute 10.33265/polar.v39.3511

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Volcanic ash (fine-grained tephra) within Greenland ice cores can complement
the understanding of past volcanism and its environmental and societal
impacts. The presence of ash in sparse concentrations in the ice raises questions
about whether such material represents primary ashfall in Greenland or
resuspended (remobilized) material from continental areas. In this article, we
investigate this issue by examining tephra content in quasi-annual samples
from two Greenland ice cores during a period of ca. 20 years and considering
their relationships with sulphur and particulate data from the same cores. We
focus on the interval 815–835 CE as it encompasses a phase (818–822 CE) of
heightened volcanogenic sulphur previously ascribed to an eruption of Katla,
Iceland. We find that tephra is a frequent but not continuous feature within
the ice, unlike similarly sized particulate matter. A solitary ash shard whose
major element geochemistry is consistent with Katla corroborates the attribution
of the 822±1 CE sulphur peak to this source, clearly showing that a single
shard can signify primary ashfall. Other tephras are present in similarly low
abundances, but their geochemistries are less certainly attributable to specific
sources. Although these tephra shards tend to coincide with elevated sulphur
and fine (<10 μm) particulates, they are not associated with increased coarse
(>10 μm) particle concentrations that might be expected if the shards had been
transported by dust storms. We conclude that the sparse shards derive from
primary ashfall, and we argue that low tephra concentrations should not be
dismissed as insignificant.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Physics Institute > Climate and Environmental Physics

Graduate School:

Graduate School of Climate Sciences

UniBE Contributor:

Sigl, Michael

Subjects:

500 Science > 530 Physics
500 Science > 540 Chemistry
500 Science > 550 Earth sciences & geology

ISSN:

0800-0395

Publisher:

Norwegian Polar Institute

Funders:

[18] European Research Council

Projects:

[1314] Timing of Holocene volcanic eruptions and their radiative aerosol forcing

Language:

English

Submitter:

Michael Sigl

Date Deposited:

07 Jul 2020 09:57

Last Modified:

06 Aug 2020 06:19

Publisher DOI:

10.33265/polar.v39.3511

Uncontrolled Keywords:

Primary ashfall resuspended volcanic ash; volcanic eruptions Katla dust storms TUNU2013 ice core Greenland aerosols tephrochronology

BORIS DOI:

10.7892/boris.145064

URI:

https://boris.unibe.ch/id/eprint/145064

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