10.6084/m9.figshare.3453923.v1
Vittorio Zanon
Vittorio
Zanon
Conditions for mafic magma storage beneath fissure zones at oceanic islands. The case of São Miguel Island (Azores archipelago)
Geological Society of London
2016
density
Regi ão dos Picos
Achada das Furnas fissure zones
Hydrocarbonic fluid inclusions
Azore
Moho
fissure zones
mafic magma storage
kg
km
S ão Miguel Island
Geology
2016-06-21 11:46:17
Dataset
https://geolsoc.figshare.com/articles/dataset/Conditions_for_mafic_magma_storage_beneath_fissure_zones_at_oceanic_islands_The_case_of_S_o_Miguel_Island_Azores_archipelago_/3453923
<p>Ponding conditions of basalts erupted from fissure zones at São Miguel Island (Azores) were investigated through microthermometry
of fluid inclusions, hosted in olivines and clinopyroxenes, and whole-rock and mineral chemistry. The Região dos Picos and
Achada das Furnas fissure zones formed between central volcanoes and erupted geochemically similar magmas for the last 30
kyr. Hydrocarbonic fluid inclusions that survived to diffusion and re-equilibration recorded a maximum density value of 1000
kg m<sup>−3</sup> (29.3 km) at both fissure zones, at the intersection with the feeding systems of older central volcanoes. The maximum density
decreases to 875 kg m<sup>−3</sup> (23.5 km) towards the central segment of Região dos Picos. Further trapping of low-density fluids is occasional and limited
to a few samples. While the deepest event is interpreted to mark the vertical variation of the Moho at each location, all
other events are only representative of short-time ponding with fluid re-equilibration. The deepening of the Moho towards
the central volcanoes might be the effect of long-lasting underplating. However, the periodic stretching of the lithosphere,
in response to the differential stress field acting at central volcanoes, would have been responsible for the thinning of
the crust at the central segment of the fissure zone.
</p>