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| Titel |
Understanding volcanism at the PETM: Abundant volcanic ash layers in the Central Tertiary Basin of Spitsbergen, Svalbard |
| VerfasserIn |
Morgan Jones, Gauti Eliassen, Henrik Svensen, Malte Jochmann, Bjarki Friis, Dougal Jerram, Sverre Planke |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250096562
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| Publikation (Nr.) |
 EGU/EGU2014-12071.pdf |
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| Zusammenfassung |
| During the early Tertiary, Svalbard developed a fold-thrust belt on its western margin with an
associated foreland basin in the central-south of what is now Spitsbergen. This Central
Tertiary Basin (CTB) is a syn-orogenic sedimentary basin in a strike-slip regime. The CTB
contains the ~1900 m thick Van Mijenfjorden group, a dominantly sandstone-shale
succession that was deposited in a North-South extending basin. Sediments in this group
display evidence of major transgressive-regressive cycles related to local tectonics and
eustatic sea level change. This basin is ideal for study as it has been extensively cored
for coal prospecting, allowing a suite of sedimentary logs across the basin to be
considered. Prominent marker beds in this sedimentary sequence are 1-30 cm thick
bentonites, formed from the chemical weathering of volcanic tuff deposits. In this
study, we focus on 8 sedimentary logs across the CTB, spanning the Palaeocene to
lower Eocene in age. Bentonites are common in the Palaeocene cores (Basilika and
Grumantbyen formations), while rarer but still occasionally present in the Eocene
Frysjaodden formation. The cores had between 3-12 observable bentonite layers that
showed large variations in preservation and subsequent reworking. Roots and other
finer organic material were common, especially when the bentonites were found
next to coal seams. Geochemical affinities between ash layers were investigated to
identify basin-wide depositional events, with the aim of elucidating the provenance
of these ashes. This sedimentary sequence is of broader interest as it covers the
Palaeocene-Eocene thermal maximum (PETM), an extreme global warming event
driven by large releases to the atmosphere of CO2 and/or CH4, evidenced by a
negative carbon isotope excursion in both the ocean and atmosphere. Potential
sources include volcanism and associated gas release from intruded sediments, CH4
hydrate dissociation, and/or the oxidation of organic matter. These formations are
poorly dated, so an objective of further study is to provide a wider range of dated
units through the formations. We also plan to assess whether the ash deposition
had a local effect on proximal ecosystems, such as fertilisation or toxicity, and/or
were contemporaneous with identifiable isotope excursions through the formations. |
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