Evolution of a Holocene delta driven by episodic sediment delivery and coseismic deformation, Puget Sound, Washington, USA
MetadataShow full item record
KeywordEarthquake; Ground-penetrating radar; Mount Rainier; Multibeam bathymetry; Puget Sound delta
Episodic, large-volume pulses of volcaniclastic sediment and coseismic subsidence of the coast have influenced the development of a late Holocene delta at southern Puget Sound. Multibeam bathymetry, ground-penetrating radar (GPR) and vibracores were used to investigate the morphologic and stratigraphic evolution of the Nisqually River delta. Two fluvial–deltaic facies are recognized on the basis of GPR data and sedimentary characteristics in cores, which suggest partial emplacement from sediment-rich floods that originated on Mount Rainier. Facies S consists of stacked, sheet-like deposits of andesitic sand up to 4 m thick that are continuous across the entire width of the delta. Flat-lying, highly reflective surfaces separate the sand sheets and comprise important facies boundaries. Beds of massive, pumice- and charcoal-rich sand overlie one of the buried surfaces. Organic-rich material from that surface, beneath the massive sand, yielded a radiocarbon age that is time-correlative with a series of known eruptive events that generated lahars in the upper Nisqually River valley. Facies CF consists of linear sandbodies or palaeochannels incised into facies S on the lower delta plain. Radiocarbon ages of wood fragments in the sandy channel-fill deposits also correlate in time to lahar deposits in upstream areas. Intrusive, sand-filled dikes and sills indicate liquefaction caused by post-depositional ground shaking related to earthquakes. Continued progradation of the delta into Puget Sound is currently balanced by tidal-current reworking, which redistributes sediment into large fields of ebb- and flood-oriented bedforms.
This paper is not subject to U.S. copyright. The definitive version was published in Sedimentology 53 (2006): 1211-1228, doi:10.1111/j.1365-3091.2006.00809.x.
Suggested CitationArticle: Barnhardt, Walter A., Sherrod, Brian L., "Evolution of a Holocene delta driven by episodic sediment delivery and coseismic deformation, Puget Sound, Washington, USA", Sedimentology 53 (2006): 1211-1228, DOI:10.1111/j.1365-3091.2006.00809.x, https://hdl.handle.net/1912/1596
Showing items related by title, author, creator and subject.
Biomarkers signal contaminant effects on the organs of English sole (Parophrys vetulus) from Puget Sound Malins, Donald C.; Anderson, Katie M.; Stegeman, John J.; Jaruga, Pawel; Green, Virginia M.; Gilman, Naomi K.; Dizdaroglu, Miral (National Institute of Environmental Health Sciences, 2006-06)Fish living in contaminated environments accumulate toxic chemicals in their tissues. Biomarkers are needed to identify the resulting health effects, particularly focusing on early changes at a subcellular level. We used ...
Malins, Donald C.; Stegeman, John J.; Anderson, Jack W.; Johnson, Paul M.; Gold, Jordan; Anderson, Katie M. (National Institute of Environmental Health Sciences, 2003-12-18)Structural differences were identified in gill DNA from two groups of English sole collected from Puget Sound, Washington, in October 2000. One group was from the industrialized Duwamish River (DR) in Seattle and the ...