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Crust and upper mantle of Kamchatka from teleseismic receiver functions

Levin V., Park J., Brandon M., Lees J., Peyton V., Gordeev E., Ozerov A. (2002) Crust and upper mantle of Kamchatka from teleseismic receiver functions // Tectonophysics. No. 358. pp. 233-256.

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Abstract

Teleseismic receiver functions (RFs) from a yearlong broadband seismological experiment in Kamchatka reveal regional variations in the Moho, anisotropy in the supra-slab mantle wedge, and, along the eastern coast, Ps converted phases from the steeply dipping slab. We analyze both radial- and transverse-component RFs in bin-averaged epicentral and backazimuthal sweeps, in order to detect Ps moveout and polarity variations diagnostic of interface depth, interface dip, and anisotropic fabric within the shallow mantle and crust. At some stations, the radial RF is overprinted by near-surface resonances, but anisotropic structure can be inferred from the transverse RF. Using forward modeling to match the observed RFs, we find Moho depth to range between 30 and 40 km across the peninsula, with a gradational crust –mantle transition beneath some stations along the eastern coast. Anisotropy beneath the Moho is required to fit the transverse RFs at most stations. Anisotropy in the lower crust is required at a minority of stations. Modeling the amplitude and backazimuthal variation of the Ps waveform suggests that an inclined axis of symmetry and 5 – 10% anisotropy are typical for the crust and the shallow mantle. The apparent symmetry axes of the anisotropic layers are typically trench-normal, but trench-parallel symmetry axes are found for stations APA and ESS, both at the fringes of the central Kamchatka depression. Transverse RFs from east-coast stations KRO, TUM, ZUP and PET are fit well by two anisotropic mantle layers with trench-normal symmetry axes and opposing tilts. Strong anisotropy in the supraslab mantle wedge suggests that the mantle ‘‘lithosphere’’ beneath the Kamchatka volcanic arc is actively deforming, strained either by wedge corner flow at depth or by trenchward suction of crust as the Pacific slab retreats.
Item Type: Article
Title: Crust and upper mantle of Kamchatka from teleseismic receiver functions
Language: English
Journal or Publication Title: Tectonophysics
ISSN Print: 0040-1951
Uncontrolled Keywords: Crust; Upper mantle; Kamchatka
Subjects: State scientific and technical information rubricator (ГРНТИ) > 37 ГЕОФИЗИКА > 37.31 Физика Земли > 37.31.19 Сейсмология
State scientific and technical information rubricator (ГРНТИ) > 38 ГЕОЛОГИЯ > 38.17 Тектоника > 38.17.91 Региональная тектоника
State scientific and technical information rubricator (ГРНТИ) > 38 ГЕОЛОГИЯ > 38.37 Петрография > 38.37.25 Вулканология
Depositing User: А.Ю. Озеров
Date Deposited: 30 Jan 2019 22:32
Last Modified: 30 Jan 2019 22:32
URI: http://repo.kscnet.ru/id/eprint/3468

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