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Accession Number ADA573758
Title CAFE Experiment: A Joint Seismic and MT Investigation of the Cascadia Subduction System.
Publication Date Feb 2013
Media Count 178p
Personal Author R. S. McGary
Abstract In this thesis we present results from inversion of data using dense arrays of collocated seismic and magnetotelluric stations located in the Cascadia subduction zone region of central Washington. In the migrated seismic section, we clearly image the top of the slab and oceanic Moho, as well as a velocity increase corresponding to the eclogitization of the hydrated upper crust. A deeper velocity increase is interpreted as the eclogitization of metastable gabbros, assisted by fluids released from the dehydration of upper mantle chlorite. A low velocity feature interpreted as a fluid/melt phase is present above this transition. The serpentinized wedge and continental Moho are also imaged. The magnetotelluric image further constrains the fluid/melt features, showing a rising conductive feature that forms a column up to a conductor indicative of a magma chamber feeding Mt. Rainier. This feature also explains the disruption of the continental Moho found in the migrated image. Exploration of the assumption of smoothness implicit in the standard MT inversion provides tools that enable us to generate a more accurate MT model. This final MT model clearly demonstrates the link between slab derived fluids/melting and the Mt. Rainier magma chamber.
Keywords Cascadia subduction system
Geophysics
Grt(Generalized radon transform)
Magnetotelluric imaging
Mohorovicic discontinuity
Radon
Seismology
Tectonics
Washington(State)


 
Source Agency Non Paid ADAS
NTIS Subject Category 48F - Geology & Geophysics
Corporate Author Massachusetts Inst. of Tech., Cambridge. Joint Program in Applied Ocean Science and Engineering.
Document Type Thesis
Title Note Doctoral thesis.
NTIS Issue Number 1318
Contract Number 0844041 0544996

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