ISSN 0869-5911, Petrology, 2007, Vol. 15, No. 5, pp. 488–508. © Pleiades Publishing, Ltd., 2007. Original Russian Text © A.B. Perepelov, M.Yu. Puzankov, A.V. Ivanov, T.M. Filosofova, E.I. Demonterova, E.V. Smirnova, L.A. Chuvashova, T.A. Yasnygina, 2007, published in Petrologiya, 2007, Vol. 15, No. 5, pp. 524–546. Neogene Basanites in Western Kamchatka: Mineralogy, Geochemistry, and Geodynamic Setting A. B. Perepelova, M. Yu. Puzankovb, A. V. Ivanovc, T. M. Filosofovab, E. I. Demonterovac, E. V. Smirnovaa, L. A. Chuvashovaa, and T. A. Yasnyginac a Vinogradov Institute of Geochemistry, Siberian Division, Russian Academy of Sciences, ul. Favorskogo 1a, Irkutsk, 664033 Russia e-mail:
[email protected] b Institute of Volcanology and Seismology, Far East Division, Russian Academy of Sciences, bul’v. Piipa 9, Petropavlosk-Kamchatskii, 683006 Russia e-mail:
[email protected] c Institute of the Earth’s Crust, Siberian Division, Russian Academy of Sciences, ul. Lermontova 128, Irkutsk, 664033 Russia e-mail:
[email protected] Received July 13, 2005 2 1 Abstract—Neogene (N1 –?N2 ) K–Na alkaline rocks were found in western Kamchatka as a subvolcanic basanite body at Mount Khukhch. The basanites have a microphyric texture with olivine phenocrysts in a fine- grained doleritic groundmass. The olivine contains inclusions of Al–Cr spinel. The microlites consist of cli- nopyroxene, plagioclase, magnetite, and apatite, and the interstitial phases are leucite, nepheline, and analcime. The Mount Khukhch basanites are characterized by elevated concentrations of MgO, TiO2, Na2O, and K2O, high concentrations of Co, Ni, Cr, Nb, Ta, Th, U, LREE (LaN/YbN = 10.8–12.6, DyN/YbN = 1.4–1.6) at moder- ate concentrations of Zr, Hf, Rb, Ba, Sr, Pb, and Cu.