Origin of eclogite and garnet pyroxenite from the

Authors: M Obata T Hirajima M Svojtka

Publish Date: 2006/08/22

Volume: 88, Issue: 1-2, Pages: 321-340

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Abstract

The granulite terrane of the Czech part of the Gföhl unit includes numerous small bodies of mantle derived peridotite some of which contain layers or lenses of eclogite and garnet pyroxenite These eclogitic rocks have generally been considered to be highpressure crystal cumulates formed in the upper mantle We present new analyses of wholerock major and trace element contents for three kynanitequartz eclogite samples taken from the Nové Dvory garnet peridotite body Integrating these data with previously published analyses from the literature on eclogitic rocks from this terrane we demonstrate that a magnesian group of eclogites including these three new samples were originally formed as cumulus gabbros which were later transformed to eclogites in the mantle A gabbroic origin for some mafic layers Type II has been advocated for other orogenic peridotites such as Beni Bousera Morocco Ronda Spain and Horoman Japan By comparing these sets of data with those from the Bohemian Massif we propose a simple method of identifying groups of metagabbros by utilizing MgOnormalization in oxide ratio plots for wholerock major element analyses

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