Publication Date:
2021-01-27
Description:
The Holocene volcanism at El Hierro consists of basaltic monogenetic
volcanic fields associated with o the three rift systems present in this island. In
this work we report preliminary petrological and geochemical data of Holocene
lava flows belonging to the WNW-striking rift. Sampling was focused in three
zones: Orchilla, Verodal-Sabinosa, and Tanganasoga. Petrography of the studied
lavas shows that they are homogeneous. All samples are porphyritic with
macrocrysts of clinopyroxene and olivine immersed in a groundmass formed
by microcrysts of plagioclase, Fe-Ti oxides and clinopyroxene. Clinopyroxenes
are diopsides, olivines have forsterite contents ranging from 74 to 84 % and
anorthite in plagioclase varies from 66 to 76% (labradorite). Whole-rock
geochemical results evidence that all magmas are basic in composition, ranging
from picrobasalts to phonotephrites. Major, trace elements and isotope support
fractional crystallization as the main process of magma evolution. However,
petrography and chemistry of clinopyroxene cores agree with a xenocrystic
nature of some of them. We suggest that these clinopyroxene cores crystallized
from a genetically related magma and subsequently were entrapped or
cannibalized by the basic rising magmas.
Description:
Published
Description:
35-38
Description:
2V. Struttura e sistema di alimentazione dei vulcani
Description:
N/A or not JCR
Keywords:
El Hierro, Holocene
;
volcanism
;
petrology
;
geochemistry
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
