AEGIRINE-AUGITE-CROSSITE-ALBITE METASOMATICS OF THE OPHIOLITE COMPLEXOF THE KHAVYVENSKAYA RANGE, EASTERN KAMCHATKA

Thin bodies of calcium metasomatics, rodingites, are widespread along the contacts between serpentinite and serpentinized harzburgite locate d in the metavolcanics of the Khavyvenskaya Range, Eastern Kamchatka, which are metamorphosed under greenschist to glaucophane facies condit ions (T = 330-390 degrees C; P = 3.3-4.4 kbar). Fragments and blocks o f the sodium alkaline rocks (up to 1-2 m across) predominantly compose d of aegirine-augite-crossite-albite metasomatics with subordinate amo unts of the bimineral aegirine-augite-albite and crossite-albite varie ties were found in the talus material. Two-three-mineral assemblages, the distinct metasomatic zonation, and zoning of the alkaline amphibol e and pyroxene of these rocks suggest their origin during the metasoma tic alteration of the metavolcanics in the tectonically weakened and f luid-permeable zones along the contacts between the serpentinized harz burgite and host metavolcanics of the upper unit of the Khavyvenskaya Group. The abundant alkaline sodium mineralization in the metavolcanic s (replacement of calcium amphibole by calcium-sodium amphibole) and t he occurrence of individual bodies of the sodium metasomatics, contain ing alkaline amphibole and pyroxene, indicate the infiltration-driven mechanism of action of the metamorphic fluids.