Identification of a Kulshan caldera correlative tephra in the Palouse loess of Washington State, northwest USA
Details
Serval ID
serval:BIB_23C6F02E1AB0
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Identification of a Kulshan caldera correlative tephra in the Palouse loess of Washington State, northwest USA
Journal
Quaternary Research
ISSN
0033-5894
1096-0287
1096-0287
Publication state
Published
Issued date
09/2016
Peer-reviewed
Oui
Volume
86
Number
02
Pages
232-241
Language
english
Abstract
The Kulshan caldera formed at ∼1.15 Ma on the present-day site of Mt. Baker, Washington State, northwest USA and erupted a compositionally zoned (dacite-rhyolite) magma and a correlative eruptive, the Lake Tapps tephra. This tephra has previously been described, but only from the Puget Lowland of NW Washington. Here an occurrence of a Kulshan caldera correlative tephra is described from the Quaternary Palouse loess at the Washtucna site (WA-3). Site WA-3 is located in east-central Washington, ∼340 km southeast of the Kulshan caldera and ∼300 km east-southeast of the Lake Tapps occurrence in the Puget Lowland. Major- and trace element chemistry and location of the deposit at Washtucna within reversed polarity sediments indicates that it is not correlative with the Mesa Falls, Rockland, Bishop Ash, Lava Creek B or Huckleberry Ridge tephras. Instead the Washtucna deposit is related to the Lake Tapps tephra by fractional crystallisation, but is chemically distinct, a consequence of its eruption from a compositionally zoned magma chamber. The correlation of the Washtucna occurrence to the Kulshan caldera-forming eruption indicates that it had an eruptive volume exceeding 100 km3, and that its tephra could provide a valuable early-Pleistocene chronostratigraphic marker in the Pacific Northwest.
Keywords
Kulshan caldera, Lake Tapps tephra, Palouse loess, Trace element geochemistry
Web of science
Create date
14/08/2018 6:47
Last modification date
23/12/2022 16:14