INVESTIGADORES
COLLO Gilda
congresos y reuniones científicas
Título:
Burial and thermal history of an unusually thick foreland basin fill in the Central Andes (28º-29º sl): signature of the Neogene flat subduction?
Autor/es:
COLLO, GILDA; DAVILA, FEDERICO; NÓBILE, JULIETA
Lugar:
Mendoza
Reunión:
Congreso; International Sedimentological Congress; 2010
Resumen:
The Vinchina
Foreland Basin in western Argentina contains a chronologically-constrained
exhumed Neogene stratigraphy with a thickness of ~10 km that shows a progressive
illitization process (R0 ® R1 ® R3), consistent with a relatively incipient burial history.
The random clay mineral ordering (R0) is persistent to a depth of ~7 km. This
clay ordering is not stable at ~120ºC and its appearance, even in the deepest
levels, is consistent with previous thermochronologic studies on detrital
apatites. The maximum paleotemperature estimation and basin depth implies a
very low geothermal gradient of ~17°C/km during the time between sedimentation
(ca. 19 Ma) and tectonic exhumation after 3.4 Ma. Therefore the Vinchina Basin is interpreted as an immature and cold
basin. Sedimentary basins recording low paleogeothermal gradients have been
attributed to thermal blanketing effects or to brief burial residence time
and/or deformation. However, the tectonic scenario of our Neogene case study
combined with results from equivalent successions from exploration wells within
the Bermejo Basin (Collo et al. this congress) indicates that this segment of
the Central Andes has had a very low heat flow transfer, comparable with the
heat contribution from the crust, with minimum input from the asthenosphere.
This suggests a refrigerated lithosphere under segments with flat subduction
and declining influence of the astenospheric wedge. Thus the geometry of
subduction may exert a strong control on the temperature flux in this and
perhaps other retroforeland sedimentary basins with similar characteristics
that may by of importance to applied studies.