Eocene Initiation of the Cascadia Subduction Zone: A Second Example of Plume-Induced Subduction Initiation?

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dc.contributor.authorStern, Robert J.
dc.contributor.authorDumitru, T. A.
dc.contributor.utdAuthorStern, Robert J.
dc.date.accessioned2020-03-30T20:12:53Z
dc.date.available2020-03-30T20:12:53Z
dc.date.issued2019-04-15
dc.descriptionIncludes supplementary material.
dc.description.abstractThe existing paradigm for the major ca. 56-48 Ma subduction zone reorganization in the Pacific Northwest of North America is that: (1) the Siletzia large igneous province erupted offshore to the west of North America, forming an oceanic plateau; (2) Siletzia then collided with North America, clogging the Pacific Northwest segment of the Cordilleran subduction zone; and (3) the oceanic lithosphere west of Siletzia then ruptured to initiate the new Cascadia subduction zone. Oceanic lithosphere is strong and difficult to rupture, so this would represent a rare example of such a rupture initiating a new subduction zone. This paper explores an alternative hypothesis for the reorganization, a plume-induced subduction initiation (PISI) mechanism, which has previously been applied to the initiation of Caribbean plate subduction zones in the Cretaceous. In this PISI hypothesis, a newly formed, ~1200-km-diameter Yellowstone mantle plume head rose at ca. 55 Ma beneath western North America, generating Siletzia in situ on the North American margin, as well as generating the ~1700-km-long Challis-Kamloops volcanic belt ~600 km to the east of Siletzia. This destroyed the existing Cordilleran subduction zone and allowed the new Cascadia subduction zone to form by collapse of thermally weakened oceanic lithosphere over the hot western margin of the plume head. This PISI hypothesis provides an integrated framework for understanding Siletzia, the Challis-Kamloops belt, Eocene core complexes from Idaho (U.S.) to British Columbia (Canada), underplated mafic rocks beneath Oregon and Washington (U.S.), post-17 Ma manifestations of the Yellowstone plume, and geophysical characteristics of the lithosphere beneath the Pacific Northwest. © 2019 The Authors.
dc.description.departmentSchool of Natural Sciences and Mathematics
dc.description.sponsorshipU.S. National Science Foundation grant EAR-0948676
dc.identifier.bibliographicCitationStern, R. J., and T. A. Dumitru. 2019. "Eocene initiation of the Cascadia subduction zone: A second example of plume-induced subduction initiation?" Geosphere 15(3): 659-681, doi: http://dx.doi.org/10.1130/GES02050.1
dc.identifier.issn1553-040X
dc.identifier.issue3
dc.identifier.urihttp://dx.doi.org/10.1130/GES02050.1
dc.identifier.urihttps://hdl.handle.net/10735.1/7680
dc.identifier.volume15
dc.language.isoen
dc.publisherGeological Society of America
dc.rightsCC BY-NC 4.0 (Attribution-NonCommercial)
dc.rights©2019 The Authors
dc.rights.urihttp://creativecommons.org/licenses/by-nc/4.0/
dc.source.journalGeosphere
dc.subjectOffshore oil industry
dc.subjectCascadia Subduction Zone
dc.subjectStructural frames
dc.subjectIgneous rocks
dc.subjectLithosphere
dc.subjectNorthwest, Pacific
dc.subjectSubduction zones
dc.subjectYellowstone River Valley
dc.subjectGeology, Structural
dc.subjectPlumes (Fluid dynamics)
dc.titleEocene Initiation of the Cascadia Subduction Zone: A Second Example of Plume-Induced Subduction Initiation?
dc.type.genrearticle

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Stern, Robert J.