Signatures of storms, oceanic floods and forearc tectonism in marine shelf strata of the Quinault Formation (Pliocene), Washington, USA

Show simple item record Campbell, Kathleen en Nesbitt, EA en Bourgeois, J en 2014-10-30T03:19:17Z en 2006-10 en
dc.identifier.citation Sedimentology, 2006, 53 (5), pp. 945 - 969 en
dc.identifier.issn 0037-0746 en
dc.identifier.uri en
dc.description.abstract Marine shelf strata of the Quinault Formation reflect the influences of storm-flood processes and convergent margin tectonism on sedimentation and palaeocommunity distributions in an active forearc basin of Early Pliocene age, western Washington, USA. The sedimentologic, ichnologic and invertebrate megafaunal character of coastal sea cliff exposures in the Pratt Cliff-Duck Creek area, Quinault Indian Nation, reveal five different sedimentary facies - scoured, Rosselia, bioturbated, mixed and Acharax. These facies document the shifting interplay and intensities among storms, waves and river-flood plumes during transgression in inner to mid-shelf settings. Storm sedimentation on the inner shelf is recorded north of Pratt Cliff by amalgamated, proximal tempestites of the scoured facies, which grade up-section to thick deposits of hummocky cross-stratified sandstone, indicative of strong wave influences. These hummocky beds alternate, in metre-scale packages, with banded mudstone and siltstone that have distinctive sedimentologic and ichnofaunal characteristics (Rosselia facies). In particular the mudstone and siltstone occur as 1-15 cm-thick, rhythmic, parallel beds that are laterally continuous, internally homogeneous to faintly laminated, and thus similar in nature to fine-grained, oceanic flood deposits reported from shelf settings offshore the modern Eel River, northern California. The Quinault flood deposits are dominated by the ubiquitous trace fossil Rosselia socialis, comprising vertical, mud-packed, flaring burrows with a sand-filled central shaft which has been inferred as the feeding-dwelling structure of a vermiform invertebrate adapted to high sedimentation rates in inner-shelf settings. Fairweather conditions in between the higher energy periods of storms, waves and floods are recorded north of Pratt Cliff by the mixed facies, which is interpreted as representing the sand and mud zone of the inner- to mid-shelf transition. Quieter, deeper, mid-shelf, fairweather settings are typified by the bioturbated facies south of Pratt Cliff, where lower sedimentation rates and lower physical energies produced extensively bioturbated deposits of sandy siltstone punctuated, in places, by isolated sandy beds of distal tempestites.Quinault strata also chronicle stratigraphic signatures of subduction of the Juan de Fuca plate beneath western Washington during the Pliocene. For example, the imprint of geochemically unusual authigenic carbonates and a chemosynthetic palaeocommunity (Acharax facies) have been interpreted as a methane seep on the Quinault seafloor. Furthermore, a mobile rockground epifauna of pholadid bivalves became established on abundant, dark mudstone cobbles and pebbles sourced from the Hoh Assemblage, a Miocene accretionary prism that was actively deforming as well as interacting with Quinault forearc sediments during the Pliocene. Hoh mudstone clasts were supplied to the Quinault shelf via seafloor-piercing diapirs and eroding melange shear zones, exposures of which today occur in fault contact with Quinault strata along the coast from Taholah to the Raft River. en
dc.language EN en
dc.publisher Blackwell Publishing en
dc.relation.ispartofseries Sedimentology en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. Details obtained from en
dc.rights.uri en
dc.subject forearc tectonism en
dc.subject marine shelf strata en
dc.subject palaeoecology en
dc.subject storm-flood sedimentation en
dc.subject trace fossils en
dc.subject TRACE FOSSILS en
dc.subject INNER SHELF en
dc.title Signatures of storms, oceanic floods and forearc tectonism in marine shelf strata of the Quinault Formation (Pliocene), Washington, USA en
dc.type Journal Article en
dc.identifier.doi 10.1111/j.1365-3091.2006.00788.x en
pubs.issue 5 en
pubs.begin-page 945 en
pubs.volume 53 en
dc.rights.holder Copyright: Blackwell Publishing en
pubs.end-page 969 en
dc.rights.accessrights en
pubs.subtype Article en
pubs.elements-id 66736 en Science en School of Environment en
dc.identifier.eissn 1365-3091 en
pubs.record-created-at-source-date 2010-09-01 en

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