PERIDOTITES FROM THE KAMCHATSKY MYS: EVIDENCE OF OCEANIC MANTLE MELTING NEAR A HOTSPOT
V.G. Batanova1,2, Z.E. Lyaskovskaya2, G.N. Savelieva3, A.V. Sobolev1,2
1Uni Grenoble Alpes, ISTerre, F-38041 Grenoble, France
2V.I. Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, ul. Kosygina 37, Moscow, 119991, Russia
3Geological Institute, Russian Academy of Sciences, Pyzhevsky per. 7, Moscow, 119017, Russia
Keywords: Kamchatka, ophiolite, lherzolite, harzburgite, clinopyroxene, proto-Hawaiian mantle plume
Abstract
A suite of mantle peridotites sampled in the Kamchatsky Mys includes spinel lherzolite, clinopyroxene-bearing harzburgite, and harzburgite. Mineral chemistry of olivine, chromian spinel, and clinopyroxene show strongly correlated element patterns typical of peridotite formed by 8% to more than 22% partial melting. Clinopyroxene in the Kamchatka peridotites is compositionally different from that of both abyssal and suprasubduction varieties: Clinopyroxene in lherzolite is depleted in LREE relative to abyssal peridotite and that in harzburgite has very low LREE and Sr unlike the subduction-related counterpart. These composition features indicate that the rocks ultra-depleted in basaltic components originated in the vicinity of a hotspot, possibly, proto-Hawaiian plume, which provided high temperature and melting degree of the MORB source mantle at mid-ocean ridge.
DOI: http://dx.doi.org/10.1016/j.rgg.2014.11.004
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