GEOCHEMISTRY AND U-PB GEOCHRONOLOGY OF ZIRCON IN GARNET AMPHIBOLITES FROM KAMCHATKSKII CAPE PENINSULA, EASTERN KAMCHATKA

Abstract

The paper presents the first data on the geochemistry and U-Pb SHRIMP geochronology of zircon from garnet amphibolites whose fragments are hosted by the sole of the ophiolite complex of Kamchatskii Cape, eastern Kamchatka. The zircons compose a homogeneous sampling, have relatively small sizes, are unhedral, have no oscillatory zoning, and possess practically no inclusions. The chemistry and photoluminescent characteristics of the zircons testify to their metamorphic genesis. The U-Pb SHRIMP dates of the zircons (81.4±9.6 Ma) indicate that the metamorphism of the amphibolite complex took place in Campanian time in the Late Cretaceous. These dates seem to correspond to the peak of the high-pressure metamorphism, which is thought to be related to the origin of an ophiolite complex of the suprasubduction type and its uplift within the Kronotskii Island arc. © Pleiades Publishing, Ltd. 2007.