INVESTIGADORES
ASTINI Ricardo Alfredo
artículos
Título:
Clay mineralogy and thermal history of the Neogene Vinchina Basin, central Andes of Argentina: Analysis of factors controlling the heating conditions.
Autor/es:
COLLO, G; DÁVILA, F. M.; NÓBILE, J.; ASTINI, R. A.; GEHRELS, G.E.
Revista:
TECTONICS
Editorial:
AMER GEOPHYSICAL UNION
Referencias:
Año: 2011 vol. 30 p. 1030 - 1052
ISSN:
0278-7407
Resumen:
The Vinchina Foreland Basin, western Argentina, contains a ∼7 km thick nonmarine
stratigraphy, chronologically constrained within the Mio‐Pliocene (circa 193.4 Ma), and
where distribution of Illite/Smectite interstratified phases has shown a progressive
smectite‐illitization progress (R0 → R1 → R3), is consistent with an incipient burial
history. R0 represents randomly mixed‐layered illite/smectite normally found at shallow
depths, as this ordering is not stable at ∼120°C. In the Vinchina Basin, however, the R0 is
still persistent at ∼7 km depth, and its appearance even in the deepest levels is consistent
with previous interpretations of low burial temperatures based on thermochronologic
studies of detrital apatites. The maximum paleotemperature estimation and basin depth
imply geothermal gradient as low as ∼15°C/km, which allowed an estimate of heat flow
values between 33 and 42 mW/m2, that would rise to between ∼40 and 51 mW/m2 when
the sedimentation rate (thermal blanketing) is taken into account. These values were only
reported for cold basins and represent a paleothermal state of a refrigerated lithosphere. We
suggest the central Andes were dominated since the Miocene by heat transfer derived
mostly from crustal contributions with a minimum input from the asthenosphere. This
refrigerated lithosphere is typical of segments affected by flat subduction. Preliminary
thermal models based on previous geodynamic approaches support our conclusions.