thumbnail

Pumice in the interglacial Whidbey Formation at Blowers Bluff, central Whidbey Island, WA, USA

Quaternary International

By:
, , ,
DOI: 10.1016/j.quaint.2007.03.013

Links

Abstract

A new 40Ar/39Ar age of 128??9 ka and chemical analyses of pumice layers from interglacial alluvium at Blowers Bluff, Whidbey Island, WA, show that the deposits are part of the Whidbey Formation, a widespread, mainly subsurface unit. Glass chemistry of the dated dacitic pumice does not match any analyzed northern Cascade source, but upper Pleistocene dacites from Glacier Peak and early Pleistocene silicic rocks from the Kulshan caldera are chemically similar. The chemistry of pumiceous dacite in younger units, including the latest Pleistocene Partridge Gravel, is similar to that of the dated material. The deep troughs of the modern northern Puget lowland must have been filled during deposition of the Whidbey Formation, allowing volcanic-rich sediment to reach what is now Whidbey Island. Topographic analysis of LIDAR images demonstrates that extensive erosion occurred during latest Pleistocene ice retreat. The Partridge Gravel likely records subglacial fluvial erosion along an ice tunnel and ice-marginal deposition into adjacent marine waters. Pumice in the Partridge Gravel probably was reworked from stratigraphically and topographically lower deposits, including those at Blowers Bluff. ?? 2007 Elsevier Ltd and INQUA.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Pumice in the interglacial Whidbey Formation at Blowers Bluff, central Whidbey Island, WA, USA
Series title:
Quaternary International
DOI:
10.1016/j.quaint.2007.03.013
Volume
178
Issue:
1
Year Published:
2008
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
229
Last page:
237
Number of Pages:
9