Magnetotelluric images of magma distribution beneath Volcán Uturuncu, Bolivia; implications for magma dynamics

The Altiplano-Puna volcanic complex in the central Andes records a history of major caldera-forming eruptions over the past 10 m.y. Geophysical and geodetic data indicate that magma is still present, and perhaps mobile, in the crust. Broadband magnetotelluric data were used to generate two-dimension...

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Bibliographic Details
Published in:Geology (Boulder) 2015-03, Vol.43 (3), p.243-246
Main Authors: Comeau, Matthew J, Unsworth, Martyn J, Ticona, Faustino, Sunagua, Mayel
Format: Article
Language:English
Subjects:
Altiplano
Andes
applied (geophysical surveys & methods)
Bolivia
Central Andes
Geodetics
geophysical methods
geophysical surveys
Geophysics
Magma
magmas
magmatism
magnetotelluric methods
Marine
Quaternary geology
resistivity
Sea level
South America
southwestern Bolivia
stratovolcanoes
surveys
three-dimensional models
two-dimensional models
Uturuncu
Volcanoes
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Summary:The Altiplano-Puna volcanic complex in the central Andes records a history of major caldera-forming eruptions over the past 10 m.y. Geophysical and geodetic data indicate that magma is still present, and perhaps mobile, in the crust. Broadband magnetotelluric data were used to generate two-dimensional and three-dimensional electrical resistivity models of the Altiplano-Puna magma body (APMB) with a focus on the zone of inflation around Volcan Uturuncu in southern Bolivia. Low electrical resistivities (20%. The upper surface of the APMB is shallowest beneath Uturuncu and the geometry is consistent with geodynamic models that require the upward movement of a melt layer at this location. The shallower resistivity structure is characterized by discrete electrically conductive bodies, oriented east-west near sea level (depth of 5 km), which are interpreted as a combination of partial melt and fluids.
ISSN:0091-7613
1943-2682
DOI:10.1130/G36258.1