BASANITES OF MT. KHUKHCH: FIRST MINERALOGICAL-GEOCHEMICAL DATA ON THE NEOGENE K-NA ALKALINE MAGMATISM IN WESTERN KAMCHATKA

Abstract

Geotectonic reconstruction of the Cenozoic structure of western Kamchatka suggests the wide development of rifting in Paleogene and Neogene in this region[1]. However, magmatic complexes typical of this geodynamic setting are as yet unknown. A Neogene subvolcanic basanite body (Mt. Khukhch) was found in the course of a geological–geochemical study of potassium alkaline magmatism in the Bystraya River basin, western Kamchatka, in 2001. The mineralogic–geochemical study of the rocks and previous data showed that the basanites of Mt. Khukhch are the first reliable evidence of the occurrence of typical within-plate K–Na alkaline magmas in the rear zone of the Kamchatka island-arc system.