Petrology and geochemistry of spinel peridotite xenoliths from the western Pannonian Basin (Hungary): evidence for an association between enrichment and texture in the upper mantle

1992 ◽  
Vol 109 (3) ◽  
pp. 340-354 ◽  
Author(s):  
H. Downes ◽  
A. Embey-Isztin ◽  
M. F. Thirlwall
Keyword(s):  
Upper Mantle ◽  
Pannonian Basin ◽  
Spinel Peridotite ◽  
Peridotite Xenoliths ◽  
Petrology And Geochemistry

scholarly journals Texture-Temperature-Geochemistry Relationships in the Upper Mantle as Revealed from Spinel Peridotite Xenoliths from Wangqing, NE China

1998 ◽  
Vol 39 (3) ◽  
pp. 469-493 ◽  
Author(s):  
Y. Xu ◽  
M. A Menzies ◽  
P. Vroon ◽  
J.-C. Mercier ◽  
C. Lin
Keyword(s):  
Upper Mantle ◽  
Spinel Peridotite ◽  
Ne China ◽  
Peridotite Xenoliths

Petrology and geochemistry of spinel peridotite xenoliths from Hannuoba and Qixia, North China craton

Lithos ◽  
2004 ◽  
Vol 77 (1-4) ◽  
pp. 609-637 ◽  
Author(s):  
Roberta L. Rudnick ◽  
Shan Gao ◽  
Wen-li Ling ◽  
Yong-shen Liu ◽  
William F. McDonough
Keyword(s):  
North China Craton ◽  
North China ◽  
Spinel Peridotite ◽  
Peridotite Xenoliths ◽  
Petrology And Geochemistry

scholarly journals Multiple Metasomatism beneath the Nógrád–Gömör Volcanic Field (Northern Pannonian Basin) Revealed by Upper Mantle Peridotite Xenoliths

2017 ◽  
Vol 58 (6) ◽  
pp. 1107-1144 ◽  
Author(s):  
Nóra Liptai ◽  
Levente Patkó ◽  
István J. Kovács ◽  
Károly Hidas ◽  
Zsanett Pintér ◽  
...  
Keyword(s):  
Upper Mantle ◽  
Pannonian Basin ◽  
Mantle Peridotite ◽  
Volcanic Field ◽  
Peridotite Xenoliths

scholarly journals Phlogopite-pargasite coexistence in an oxygen reduced spinel-peridotite ambient

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Costanza Bonadiman ◽  
Valentina Brombin ◽  
Giovanni B. Andreozzi ◽  
Piera Benna ◽  
Massimo Coltorti ◽  
...  
Keyword(s):  
Oxygen Fugacity ◽  
Upper Mantle ◽  
Mantle Xenoliths ◽  
Spinel Peridotite ◽  
Simultaneous Formation ◽  
Empirical Potentials ◽  
Elastic Data ◽  
Mineralogical Study ◽  
Semi Empirical ◽  
T Locus

AbstractThe occurrence of phlogopite and amphibole in mantle ultramafic rocks is widely accepted as the modal effect of metasomatism in the upper mantle. However, their simultaneous formation during metasomatic events and the related sub-solidus equilibrium with the peridotite has not been extensively studied. In this work, we discuss the geochemical conditions at which the pargasite-phlogopite assemblage becomes stable, through the investigation of two mantle xenoliths from Mount Leura (Victoria State, Australia) that bear phlogopite and the phlogopite + amphibole (pargasite) pair disseminated in a harzburgite matrix. Combining a mineralogical study and thermodynamic modelling, we predict that the P–T locus of the equilibrium reaction pargasite + forsterite = Na-phlogopite + 2 diopside + spinel, over the range 1.3–3.0 GPa/540–1500 K, yields a negative Clapeyron slope of -0.003 GPa K–1 (on average). The intersection of the P–T locus of supposed equilibrium with the new mantle geotherm calculated in this work allowed us to state that the Mount Leura xenoliths achieved equilibrium at 2.3 GPa /1190 K, that represents a plausible depth of ~ 70 km. Metasomatic K-Na-OH rich fluids stabilize hydrous phases. This has been modelled by the following equilibrium equation: 2 (K,Na)-phlogopite + forsterite = 7/2 enstatite + spinel + fluid (components: Na2O,K2O,H2O). Using quantum-mechanics, semi-empirical potentials, lattice dynamics and observed thermo-elastic data, we concluded that K-Na-OH rich fluids are not effective metasomatic agents to convey alkali species across the upper mantle, as the fluids are highly reactive with the ultramafic system and favour the rapid formation of phlogopite and amphibole. In addition, oxygen fugacity estimates of the Mount Leura mantle xenoliths [Δ(FMQ) = –1.97 ± 0.35; –1.83 ± 0.36] indicate a more reducing mantle environment than what is expected from the occurrence of phlogopite and amphibole in spinel-bearing peridotites. This is accounted for by our model of full molecular dissociation of the fluid and incorporation of the O-H-K-Na species into (OH)-K-Na-bearing mineral phases (phlogopite and amphibole), that leads to a peridotite metasomatized ambient characterized by reduced oxygen fugacity.

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