Publikationsdatum:
2020-02-24
Beschreibung:
Petrographic, minerochemical, and geothermobarometric data are reported for a suite of
spinel-lherzolite pargasite xenoliths hosted in a Quaternary basanitic lava flow from
the North-Western Ethiopian Plateau (Injibara, Lake Tana Province). Protogranular to
porphyroclastic (deformed) rocks show evidence of a modal metasomatism, represented
by a Cl-rich pargasitic amphibole, coupled with cryptic enrichment in Fe and Al.
Equigranular rocks (granular) record a further cryptic metasomatism, represented by
enrichment in Fe, Al, Na, and depletion in Ni, Cr and Cl. Some xenoliths (transitional)
show intermediate textural and compositional characters, indicating that the granular
samples represent an evolution of the deformed ones. All xenoliths give the same P–T
equilibration conditions for Opx-Cpx pairs (947–1015 C and 1.3–2.0 GPa), but in
granular samples, recrystallised olivine and spinel record T about 100 C higher. Two distinct metasomatic processes, probably connected with the emplacement of the Afar
plume, are proposed. The first one is a pervasive modal metasomatism produced by
water-rich fluids. The latter is a non-pervasive cryptic metasomatism, probably connected
to migration of melts. The comparison the mantle beneath the Ethiopian
Volcanic Plateau, the southern Main Ethiopian Rift and the central Main Ethiopian
Rift suggests spatial heterogeneity of the mantle and variable mantle processes during
asthenospheric upwelling.
Beschreibung:
Published
Beschreibung:
47-78
Beschreibung:
3.3. Geodinamica e struttura dell'interno della Terra
Beschreibung:
JCR Journal
Beschreibung:
reserved
Schlagwort(e):
lithosphere
;
peridotite xenoliths
;
Ethiopian Volcanic Plateau
;
Metasomatism
;
04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology
Repository-Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Materialart:
article
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