INVESTIGADORES
COLLO Gilda
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, GILDA; DAVILA, FEDERICO; NÓBILE, JULIETA; ASTINI, RICARDO A.; GEHRELS, GEORGE
Revista:
TECTONICS
Editorial:
AMER GEOPHYSICAL UNION
Referencias:
Año: 2011 vol. 30 p. 1 - 18
ISSN:
0278-7407
Resumen:
The Vinchina
Foreland Basin, western Argentina, contains a ~7 km thick non-marine
stratigraphy, chronologically constrained within the Mio-Pliocene (ca. 19 to
3.4 Ma), and where distribution of Illite/Smectite interstratified phases has
shown a progressive smectite-illitization progress (R0-R1-R3),
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 ~120ºC. 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 to estimate heat flow values between 33 and 42 mW/m2, that
would raise 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 flow
transfer derived mostly from crustal contributions with a minimum input from
the asthenosphere. This refrigerated lithosphere is typical of segments
affected by flat subduction, where thin asthenospheric wedges exert a poor
thermal influence on the overall heat flow balance. Preliminary thermal models
based on previous geodynamic approaches support our conclusions.