Magmatic and Sedimentary Structure beneath the Klyuchevskoy Volcanic Group, Kamchatka, From Ambient Noise Tomography

Autor: Andrey Jakovlev, Birger Luehr, Jennifer Dreiling, Evgeny Gordeev, Ivan Koulakov, Ilyas Abkadyrov, Christoph Sens-Schönfelder, Nikolai M. Shapiro, Frederik Tilmann, Robert G. Green, Dima Droznin
Přispěvatelé: Shapiro, Nikolai, 2 Institut de Sciences de la Terre Université Grenoble Alpes, CNRS (UMR5275) Grenoble France, Koulakov, Ivan, 4 Trofimuk Institute of Petroleum Geology and Geophysics Siberian Branch of the Russian Academy of Sciences Novosibirsk Russian Federation, Tilmann, Frederik, 1 Department of Geophysics Helmholtzzentrum Potsdam, Deutsches GeoForschungsZentrum (GFZ) Potsdam Germany, Dreiling, Jennifer, Luehr, Birger, Jakovlev, Andrey, Abkadyrov, Ilyas, Droznin, Dima, 8 Kamchatka Branch of the Geophysical Service Russian Academy of Sciences Petropavlovsk‐Kamchatsky Russian Federation, Gordeev, Evgeny, 7 Institute of Volcanology and Seismology FEB RAS Petropavlovsk‐Kamchatsky Russia, GeoForschungsZentrum - Helmholtz-Zentrum Potsdam (GFZ), Institut des Sciences de la Terre (ISTerre), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Grenoble Alpes (UGA)-Université Gustave Eiffel-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), A.A. Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences (SB RAS), Institute of Volcanology and Seismology of the RAS, Far Eastern Branch of the Russian Academy of Sciences (FEB RAS), Kamchatka Branch of the Geophysical Service, Russian Academy of Sciences [Moscow] (RAS), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Gustave Eiffel-Université Grenoble Alpes (UGA), ​Trofimuk Institute of Petroleum Geology and Geophysics of the Siberian Branch of the RAS (IPGG SB RAS)
Jazyk: angličtina
Předmět:
Zdroj: Journal of Geophysical Research : Solid Earth
Journal of Geophysical Research : Solid Earth, American Geophysical Union, 2020, 125 (3), pp.e2019JB018900. ⟨10.1029/2019JB018900⟩
Journal of Geophysical Research : Solid Earth, 2020, 125 (3), pp.e2019JB018900. ⟨10.1029/2019JB018900⟩
Journal of Geophysical Research: Solid Earth
ISSN: 2169-9356
2169-9313
DOI: 10.1029/2019jb018900
Popis: The Klyuchevskoy Volcanic Group is a cluster of the world's most active subduction volcanoes, situated on the Kamchatka Peninsula, Russia. The volcanoes lie in an unusual off‐arc position within the Central Kamchatka Depression (CKD), a large sedimentary basin whose origin is not fully understood. Many gaps also remain in the knowledge of the crustal magmatic plumbing system of these volcanoes. We conducted an ambient noise surface wave tomography, to image the 3‐D shear wave velocity structure of the Klyuchevskoy Volcanic Group and CKD within the surrounding region. Vertical component cross correlations of the continuous seismic noise are used to measure interstation Rayleigh wave group and phase traveltimes. We perform a two‐step surface wave tomography to model the 3‐D Vsv velocity structure. For each inversion stage we use a transdimensional Bayesian Monte Carlo approach, with coupled uncertainty propagation. This ensures that our model provides a reliable 3‐D velocity image of the upper 15 km of the crust, as well as a robust assessment of the uncertainty in the observed structure. Beneath the active volcanoes, we image small slow velocity anomalies at depths of 2–5 km but find no evidence for magma storage regions deeper than 5 km—noting the 15 km depth limit of the model. We also map two clearly defined sedimentary layers within the CKD, revealing an extensive 8 km deep sedimentary accumulation. This volume of sediments is consistent with the possibility that the CKD was formed as an Eocene‐Pliocene fore‐arc regime, rather than by recent (
Plain Language Summary: The Klyuchevskoy Volcanic Group is a cluster of 13 volcanoes on the Kamchatkan corner of the Pacific ring of fire. The volcanoes regularly produce large eruptions, but good knowledge of the magma plumbing system beneath the surface is still lacking. Why the Klyuchevskoy Volcanic Group volcanoes lie in the location they do, in a large low‐lying depression, is also unexplained. We undertook a seismic experiment and used the data to produce a 3‐D velocity image of the subsurface beneath the volcanoes and the depression. We found that small regions of slow seismic velocity are located beneath the active volcanoes, at 2–5 km depth below sea level. This slower velocity is probably caused by magma lying within the porous fracture spaces in this rock. The seismic velocities are much faster beneath the dormant volcanoes, suggesting they have no magma beneath them. With our velocity image, we also find that the Central Kamchatka Depression is very deep, filled with over 8 km of sediments. This supports an idea that the sediments accumulated as a fore‐arc basin over many millions of years, since 40 Ma, when the active line of volcanoes was found 100 km to the west.
Key Points: Three‐dimensional shear velocity structure of the Klyuchevskoy area was determined using coupled transdimensional Monte Carlo inversions. Slow velocity anomalies suggest magma storage beneath active volcanoes at 2–5 km depth (below sea level) but not in the midcrust. Sediments filling the Central Kamchatka Depression are 8 km deep, consistent with an origin of the depression as a fore‐arc basin.
European Union Horizon 2020 Research and Innovation Programme http://dx.doi.org/10.13039/501100007601
Russian Ministry of Education and Science http://dx.doi.org/10.13039/501100003443
Alexander von Humboldt Foundation http://dx.doi.org/10.13039/100005156
Databáze: OpenAIRE
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