Mantle flow and deep electrical anisotropy in a main gateway: MT study in Tierra del Fuego
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Springer Nature
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2019-05-09Referencia bibliográfica
González-Castillo, L., Bohoyo, F., Junge, A., Galindo-Zaldívar, J., Cembrowski, M., Torres-Carbonell, P., ... & Ruano, P. (2019). Mantle flow and deep electrical anisotropy in a main gateway: MT study in Tierra del Fuego. Scientific reports, 9(1), 1-6.
Patrocinador
This work was supported through projects CTM2014-60451-C2-02/01 and CTM2017-89711-C2-2/1-P from Ministry of Science, Innovation and Universities of Spain and the RNM-148 from Junta de Andalucía (Spain).Resumen
Asthenospheric mantle flow drives lithospheric plate motion and constitutes a relevant feature of
Earth gateways. It most likely influences the spatial pattern of seismic velocity and deep electrical
anisotropies. The Drake Passage is a main gateway in the global pattern of mantle flow. The separation
of the South American and Antarctic plates since the Oligocene produced this oceanic and mantle
gateway connecting the Pacific and Atlantic oceans. Here we analyze the deep crustal and upper mantle
electrical anisotropy of its northern margin using long period magnetotelluric data from Tierra del
Fuego (Argentina). The influence of the surrounding oceans was taken into account to constrain the
mantle electrical conductivity features. 3D electrical models were calculated to fit 18 sites responses
in this area. The phase tensor pattern for the longest periods reveals the existence of a well-defined
NW-SE electrical conductivity anisotropy in the upper mantle. This anisotropy would result from
the mantle flow related to the 30 to 6 Ma West Scotia spreading, constricted by the subducted slab
orientation of the Pacific plate, rather than the later eastward mantle flow across the Drake Passage.
Deep electrical anisotropy proves to be a key tool for a better understanding of mantle flow.