Dynamics of the 240 A.D. caldera-forming eruption of Ksudach Volcano, Kamchatka, Russia
Thesis (M.S.) University of Alaska Fairbanks, 2004 The Ksudach Volcano KS-1 rhyodacite deposits offer an opportunity to study eruption dynamics and plume stability during a caldera-forming eruption. Stratigraphic relations indicate four phases of eruption, Initial, Main, Lithic, and Gray. Well-sorte...
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ftunivalaska:oai:scholarworks.alaska.edu:11122/6004 2023-05-15T16:59:20+02:00 Dynamics of the 240 A.D. caldera-forming eruption of Ksudach Volcano, Kamchatka, Russia Andrews, Benjamin James 2004-08 http://hdl.handle.net/11122/6004 en_US eng http://hdl.handle.net/11122/6004 Department of Geology and Geophysics Thesis ms 2004 ftunivalaska 2023-02-23T21:36:34Z Thesis (M.S.) University of Alaska Fairbanks, 2004 The Ksudach Volcano KS-1 rhyodacite deposits offer an opportunity to study eruption dynamics and plume stability during a caldera-forming eruption. Stratigraphic relations indicate four phases of eruption, Initial, Main, Lithic, and Gray. Well-sorted, reverse-graded pumice fall deposits overlying a silty ash compose the Initial phase layers. The Main, Lithic and Gray phases are represented by pumice fall layers interbedded with pyroclastic flow and surge deposits (proximally) and co-ignimbrite ashes (distally). Although most of the deposit is <30 wt.% lithics, the Lithic phase layers are>50wt.% lithics. White and gray pumices are compositionally indistinguishable, however vesicle textures and microlite populations indicate faster ascent by the white pumices prior to the Gray phase. The eruption volume is estimated as 7.5 km³ magma (dense rock equivalent) and 2.4 km³ lithics. Isopleth maps indicate mass discharge rates (MDR) ranged from 5-10x10⁷ kg/s in the Initial phase to> 10⁸ kg/s in the Main, Lithic, and Gray phases. Stratigraphic, granulometric, and component analyses indicate simultaneous eruption of buoyant plumes and non-buoyant flows during the Main, Lithic and Gray phases. Caldera collapse during the Lithic phase is reflected by a large increase in lithic particles and the textural change from white to gray pumices; collapse occurred after eruption of 2/3 of the magma. Thesis Kamchatka Alaska University of Alaska: ScholarWorks@UA Fairbanks |
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University of Alaska: ScholarWorks@UA |
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English |
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Thesis (M.S.) University of Alaska Fairbanks, 2004 The Ksudach Volcano KS-1 rhyodacite deposits offer an opportunity to study eruption dynamics and plume stability during a caldera-forming eruption. Stratigraphic relations indicate four phases of eruption, Initial, Main, Lithic, and Gray. Well-sorted, reverse-graded pumice fall deposits overlying a silty ash compose the Initial phase layers. The Main, Lithic and Gray phases are represented by pumice fall layers interbedded with pyroclastic flow and surge deposits (proximally) and co-ignimbrite ashes (distally). Although most of the deposit is <30 wt.% lithics, the Lithic phase layers are>50wt.% lithics. White and gray pumices are compositionally indistinguishable, however vesicle textures and microlite populations indicate faster ascent by the white pumices prior to the Gray phase. The eruption volume is estimated as 7.5 km³ magma (dense rock equivalent) and 2.4 km³ lithics. Isopleth maps indicate mass discharge rates (MDR) ranged from 5-10x10⁷ kg/s in the Initial phase to> 10⁸ kg/s in the Main, Lithic, and Gray phases. Stratigraphic, granulometric, and component analyses indicate simultaneous eruption of buoyant plumes and non-buoyant flows during the Main, Lithic and Gray phases. Caldera collapse during the Lithic phase is reflected by a large increase in lithic particles and the textural change from white to gray pumices; collapse occurred after eruption of 2/3 of the magma. |
format |
Thesis |
author |
Andrews, Benjamin James |
spellingShingle |
Andrews, Benjamin James Dynamics of the 240 A.D. caldera-forming eruption of Ksudach Volcano, Kamchatka, Russia |
author_facet |
Andrews, Benjamin James |
author_sort |
Andrews, Benjamin James |
title |
Dynamics of the 240 A.D. caldera-forming eruption of Ksudach Volcano, Kamchatka, Russia |
title_short |
Dynamics of the 240 A.D. caldera-forming eruption of Ksudach Volcano, Kamchatka, Russia |
title_full |
Dynamics of the 240 A.D. caldera-forming eruption of Ksudach Volcano, Kamchatka, Russia |
title_fullStr |
Dynamics of the 240 A.D. caldera-forming eruption of Ksudach Volcano, Kamchatka, Russia |
title_full_unstemmed |
Dynamics of the 240 A.D. caldera-forming eruption of Ksudach Volcano, Kamchatka, Russia |
title_sort |
dynamics of the 240 a.d. caldera-forming eruption of ksudach volcano, kamchatka, russia |
publishDate |
2004 |
url |
http://hdl.handle.net/11122/6004 |
geographic |
Fairbanks |
geographic_facet |
Fairbanks |
genre |
Kamchatka Alaska |
genre_facet |
Kamchatka Alaska |
op_relation |
http://hdl.handle.net/11122/6004 Department of Geology and Geophysics |
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1766051566356267008 |