Physical Sciences and Mathematics Commons^™

The Sedimentary Petrography, Depositional Environment And Tectonic Setting Of The Aldwell Formation, Northern Olympic Peninsula, Washington, Keith Marcott

WWU Graduate School Collection

The upper Eocene Aldwell Formation crops out in an east-west trending band across the northern Olympic Peninsula, Washington. Petrographic analyses indicate that the Aldwell Formation has lithologically distinctive eastern and western portions. The rocks of the eastern Aldwell are basalt-rich lithic greywackes; their mean compositions are Qm-F-Lt: 5- 22-73 and polycrystalline quartz-volcanic rock fragments-total sedimentary rock fragments: 1-78-21. The rocks of the western Aldwell are chert-rich lithic arenites; their mean compositions are Qm-F-Lt: 27-19-54 and polycrystalline quartz-volcanic rock fragments-total sedimentary rock fragments: 66-11-23.

Similarities in texture, composition, and alteration products suggest that the basalts of the Crescent seamount province as …