Rare earth element (REE) abundances have been determined in six samples of metabasites from the Pennidic Adula nappe in the area of Soazza (Mesolcina Valley, Switzerland). The samples cover a broad range of mineralogical composition from eclogite to epidote amphibolite through symplectitic garnet amphibolite. The REE patterns do not vary significantly and indicate a common origin of these rocks as "normal" mid-ocean ridge basalts (N-MORB). Two main eclogitic phases, clinopyroxene (cpx) and garnet (grt), have also been analysed for REE and other trace elements (Sc, V, Cr, Co, Ni, Cu, Zn, Sr, Y, Zr). The incorporation of REE and most trace elements in structural sites of cpx and grt is in accordance with that expected mainly from an evaluation of site geometry, ionic radius and charge balance and is therefore dependent on the major-element composition of the host phases. The changes in cpx/grt partition coefficients (Di) for HREE are particularly associated with the temperature condition of the equilibration of the pair.

Trace element distribution in eclogites and their clinopyroxene/garnet pair:a case study from Soazza (Switzerlan) / R. Bocchio, L. De Capitani, L. Ottolini, F. Cella. - In: EUROPEAN JOURNAL OF MINERALOGY. - ISSN 0935-1221. - 12:1(2000 Feb), pp. 147-161. [10.1127/​0935-1221/​2000/​0012-0147]

Trace element distribution in eclogites and their clinopyroxene/garnet pair:a case study from Soazza (Switzerlan)

R. Bocchio
Primo
;
L. De Capitani
Secondo
;
2000

Abstract

Rare earth element (REE) abundances have been determined in six samples of metabasites from the Pennidic Adula nappe in the area of Soazza (Mesolcina Valley, Switzerland). The samples cover a broad range of mineralogical composition from eclogite to epidote amphibolite through symplectitic garnet amphibolite. The REE patterns do not vary significantly and indicate a common origin of these rocks as "normal" mid-ocean ridge basalts (N-MORB). Two main eclogitic phases, clinopyroxene (cpx) and garnet (grt), have also been analysed for REE and other trace elements (Sc, V, Cr, Co, Ni, Cu, Zn, Sr, Y, Zr). The incorporation of REE and most trace elements in structural sites of cpx and grt is in accordance with that expected mainly from an evaluation of site geometry, ionic radius and charge balance and is therefore dependent on the major-element composition of the host phases. The changes in cpx/grt partition coefficients (Di) for HREE are particularly associated with the temperature condition of the equilibration of the pair.
SIMS ; trace elements ; distribution coefficient ; eclogite ; Central Alps
Settore GEO/06 - Mineralogia
Settore GEO/08 - Geochimica e Vulcanologia
Settore GEO/07 - Petrologia e Petrografia
feb-2000
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/180123
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