Clinopyroxene megacrysts from Enmelen melanephelinitic volcanoes (Chukchi Peninsula,Russia): application to composition and evolution of mantle melts |
| |
| Authors: | Email author" target="_blank">Vyacheslav?V?AkininEmail author Alexander?V?Sobolev Theodoros?Ntaflos Wolfram?Richter |
| |
| Institution: | (1) North-East Interdisciplinary Science Research Institute, Russian Academy of Sciences, Portovaya Street 16, Magadan, Russia, 685000;(2) Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, Kosygina St., 19, Moscow, 117975, Russia;(3) Institute of Petrology, University of Vienna – Geozentrum, Althanstr. 14, , Austria |
| |
| Abstract: | Clinopyroxene megacrysts from young melanephelinitic lavas were divided into Cr-rich and Cr-poor suites. Sr, Nd, and Pb isotopic
ratios of leached megacrysts and host lava are indistinguishable from each other and indicate a depleted source. Host lavas
do not display chemical evidence for significant fractional crystallization, which is required to explain the compositional
range of the megacrysts. This rules out a simple cognate genetic relationship between the two, and strictly defines megacrysts
as xenocrysts. The well-defined correlations of trace elements with the Mg-numbers in the megacrysts are interpreted as the
result of extensive fractional/equilibrium crystallization of magma over a large temperature range at near isobaric condition
in the upper mantle. Trace element variations in megacrysts are consistent with fractional crystallization of clinopyroxene
alone for the Cr-rich suite, and clinopyroxene + garnet for the Cr-poor suite from at least two bathes of related melts. Megacrysts
parent magma might represent mantle melts, which were never erupted in their initial composition. |
| |
| Keywords: | |
| 本文献已被 SpringerLink 等数据库收录！ |
|
