Gavrilenko, M.

Herzberg, C. T.

Ozerov, A.

Portnyagin, Maxim

English

OceanRep

1/2CONTROL ID: 1468918TITLE: Identification of source lithology at south segment of Kamchatka subduction zoneAUTHORS (FIRST NAME, LAST NAME): Maxim Gavrilenko1, 2, Claude T Herzberg1, MaximPortnyagin3, 4, Alexey Ozerov2INSTITUTIONS (ALL): 1. Department of Earth and Planetary Sciences, Rutgers, The StateUniversity of New Jersey, Piscataway, NJ, United States. 2. Institute of Volcanology and Seismology, Petropavlovsk-Kamchatsky, Russian Federation. 3. Leibniz Institute of Marine Research, IFM-GEOMAR, Kiel, Germany. 4. Vernadsky Institute of Geochemistry and Analytical Chemistry, Moscow, Russian Federation. ABSTRACT BODY: Kamchatka peninsula (Russia) is an island-arc with a complex geologicalhistory and structure. It has three distinct volcanic fronts, the origin of which is still debated.Moreover, a junction with the Aleutian Arc (at ~56°N) complicates the understanding ofgeodynamics at the region. However, the south part (from ~53°N) of Kamchatka peninsula is thoughtto be a “textbook case” of subduction zone with relatively rapid (over 8 cm/yr) near-normalconvergence and a steep (over 50°) angle of subduction. Kamchatka is unusual in the world becauseits volcanoes contain a significant amount of primitive high MgO lavas that are rich in olivine crystals.Furthermore, high precision contents of Ni, Ca, and Mn can help to constrain the source lithology.Straub et al. (2008) reported high Ni contents on olivines from a limited number of samples from theMexican Volcanic Front, and concluded that pyroxenite melting was important. Portnyagin et al.(2009) reported high precision Ni, Ca, and Mn contents of olivines from a wide range of volcanoesfrom Kamchatka, and similarly concluded that pyroxenite melting is widespread. We have extendedthe work of Portnyagin et al. (2009) by analyzing olivine phenocrysts from volcanoes in thesouthernmost Kamchatka peninsula. Our work confirms that there are regional variations in olivinephenocryst composition that likely arises from variations in pyroxenite composition, the amount ofperidotite melt that mixes with pyroxenite melts, and a variable role played by magnetite fractionation.We conclude that pyroxenite melting is likely to be important in subduction zones world-wide, but itssignificance has been underestimated because of the general rarity of olivine-bearing high MgO lavas.KEYWORDS: [1025] GEOCHEMISTRY / Composition of the mantle, [1037]GEOCHEMISTRY / Magma genesis and partial melting, [1031] GEOCHEMISTRY / Subductionzone processes, [8413] VOLCANOLOGY / Subduction zone processes.(No Image Selected)(No Table Selected)Additional DetailsPreviously Presented Material:Contact DetailsCONTACT (NAME ONLY): Maxim Gavrilenko10/14/12CONTACT (E-MAIL ONLY): max.gavrilenko@gmail.comTITLE OF TEAM:

Identification of source lithology at south segment of Kamchatka subduction zone

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