Trace elements in olivine grains from volcanic rocks

• Main Author: Gavrilenko, Maxim
• Format: Text
• Language: unknown
• Published: No Publisher Supplied 2016
• Subjects: Pacific; Kamchatka
• Online Access: https://dx.doi.org/10.7282/t31n83f2; https://rucore.libraries.rutgers.edu/rutgers-lib/51293/

My study focused on magmatic evolution in different tectonic settings using mostly olivine, and volcanic whole rock chemistry together with the compositions of the minerals that it hosts, such as pyroxenes, plagioclase, spinel, and magnetite. Although volcanoes of the spreading centers (e.g. East Pacific Rise) provide the more direct petrological information about the mantle, subduction zone volcanoes are the center of attention on my research. I worked with samples from Kamchatka arc volcanoes (Gorely, Klyuchevskoy, Shiveluch) and from Central America volcanoes (Platanar, Barva, Irazu). However, samples of rocks from a spreading center (Siqueiros Fracture Zone) were also used in my study. The compositions of incompatible elements in olivine, such as Ca, Mn, Ni, Al, P, and their distribution within the olivine crystal (zoning pattern) provide important petrologic information. The concentration of Ca in olivine is demonstrated to help estimate magmatic water content. The compositions of olivine and coexisting minerals help to evaluate such physical parameters as pressure (Ol-Cpx pair) and temperature (Ol-Sp pair). For instance, the distribution of Al between host olivine and spinel inclusion provides information about crystallization temperature. In my study I helped to evaluate the depth of sub-crustal magma chamber beneath Klyuchevskoy volcano (Kamchatka). I estimated conditions and contribution of mechanisms of differentiation (such as magma mixing, crustal assimilation, and fractional crystallization) for magma evolution in the different parts of Gorely volcano (Kamchatka). I used experimental and natural olivine compositions in order to calibrate the Ca-in-olivine geohygrometer, which provides magmatic H2O content independently from melt inclusion studies. In addition, I participated in the discovery of "primary" olivines ("pyrocrysts"), which crystallized in the hottest parts of melting regions (both in subduction zones and in spreading centers).