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Gravity map of the Isla Grande de Tierra del Fuego, and morphology of Lago Fagnano
Ist Teil von
Geologica acta, 2007, Vol.5 (4), p.307-314
Ort / Verlag
Institut de Ciències de la Terra "Jaume Almera"
Erscheinungsjahr
2007
Quelle
Free E-Journal (出版社公開部分のみ)
Beschreibungen/Notizen
A complete Bouguer gravity map of the central-eastern part of the Isla Grande de Tierra del Fuego, and a general
bathymetric chart of the Lago Fagnano have been realized, on the basis of a series of field geophysical surveys carried
out on the Island since 1998. The regional gravity anomaly trend onshore shows a progressive negative gradient
from N to S. Distinct, broadly E-W-trending gravity minima are superimposed on this regional negative gradient.
They follow the main trace of the Magallanes-Fagnano fault system, which represents the western segment of
the left-lateral South America-Scotia transform plate boundary. The gravity minima reflect the presence in the subsurface
of restricted and elongated basins developed within the principal displacement zone of the fault system. A
relative positive gravity maximum is located just at the SE corner of the Lago Fagnano, and represents the
response of a partially exposed crystalline body, occupying an area 3 x 3 km wide. A 2D vertical crustal model has
been constructed, combining gravity data inversion and geological information available for the central-eastern
region of Lago Fagnano. The bathymetric map of the Lago Fagnano delineates the main morphological features of
this 110-km-long, 7-km-wide lake, the largest of Isla Grande. The floor is divided into distinct parts, which suggests
that the basin is composed of different sub-basins. In most areas, the basin floor is highly asymmetric in
shape, with flat depocentral areas. The most pronounced asymmetry of the basin is seen in the eastern end of the
lake, where there is also the deepest depression. The steeper slope of the basin, along the northern shore of the
Lago Fagnano, also coincides with the most pronounced regional topographic gradient. The general gravimetric
and morphological features of the investigated region are here discussed.