Extending the Late Holocene Tephrochronology of the Central Kenai Peninsula, Alaska
ABSTRACT. Tephrochronology, the reconstruction of past volcanic ash deposition, provides a valuable method for dating sediments and determining long-term volcanic history. Tephra layers are highly numerous in Alaska, but knowledge of their occurrence and distribution is incomplete. This study expand...
| Main Authors: | , |
|---|---|
| Other Authors: | |
| Format: | Text |
| Language: | English |
| Published: |
2006
|
| Subjects: | |
| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.501.8705 http://pubs.aina.ucalgary.ca/arctic/Arctic61-3-243.pdf |
| Summary: | ABSTRACT. Tephrochronology, the reconstruction of past volcanic ash deposition, provides a valuable method for dating sediments and determining long-term volcanic history. Tephra layers are highly numerous in Alaska, but knowledge of their occurrence and distribution is incomplete. This study expands the regional tephrochronology for the Kenai Peninsula of south-central Alaska by investigating the tephrostratigraphy of two peatland sites. We located seven visible tephras and seven microtephras and investigated the particle size and geochemistry of the visible tephras. Radiocarbon dates were used to estimate the timescale of each core. Geochemical comparison showed that the visible tephras originated from late Holocene eruptions of Augustine, Crater Peak–Mt. Spurr, and Hayes volcanoes. Some of the tephras had been documented previously, and these new findings expand their known range. Others represent eruptions not previously reported, including a Crater Peak–Mt. Spurr eruption around 430 cal. BP. The results provide new tephra data for the region, illustrate the spatial heterogeneity of tephra deposition, and show the potential of microtephras for expanding the regional tephra record. Key words: tephra, cryptotephra, peatlands, Alaska, volcanoes, electron probe microanalysis RÉSUMÉ. La téphrochronologie, soit la reconstruction d’anciens dépôts de cendres volcaniques, constitue une méthode valable pour dater les sédiments et déterminer l’historique des volcans à long terme. En Alaska, les couches de téphra sont nombreuses, mais on ne sait pas tout sur leur occurrence et leur répartition. Cette étude a permis d’approfondir la téphrochronologie régionale de la péninsule de Kenai du centre-sud de l’Alaska grâce à la téphrostratigraphie de deux tourbières. Nous avons repéré sept téphras |
|---|