Clay mineralogy and thermal history of the Neogene Vinchina Basin, central Andes of Argentina: Analysis of factors controlling the heating conditions

Abstract

[1] The Vinchina Foreland Basin, western Argentina, contains a ∼7 km thick nonmarine stratigraphy, chronologically constrained within the Mio-Pliocene (circa 19-3.4 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/m 2 , that would rise to between ∼40 and 51 mW/m 2 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.

The evolution of the high‐elevated depocenters of the northern Sierras Pampeanas (ca. 28˚ SL), Argentine broken foreland, South‐Central Andes: the Pipanaco Basin

“…12), a minimum exhumation of ca.7.5 km would be expected since the Late Miocene along the northern margin of the Pipanaco basin. This estimation is supported by low-temperature thermochronology and burial studies (Coughlin, 2000;Collo et al, 2011), which yields Miocene cooling ages of <8 Ma (the youngest record in the Sierras Pampeanas), preserved under very low geotherms <17°C/km (Collo et al, 2011). Such thermal conditions would require 5-7 km of exhumation to exhume rocks from below the apatite fissiontrack closure temperature (between 120°C and 90°C, Reiners et al, 2005).…”

A thermochronometric view into an ancient landscape: Tectonic setting, development, and inversion of the Paleozoic eastern Paganzo basin, Argentina

“…Recent studies of illitization processes in the Neogene Vinchina Basin, located farther northwest of the Sierra de Chepes (Fig. 4), have suggested a very low geothermal gradient of 15-18 °C/km (Collo et al, 2011), which would allow a much larger amount of rock exhumation without exhumation of rocks from below the apatite (U-Th)/He or FT closure temperature. Davila and Carter (2013) revisited published apatite FT data from the western ranges of the Sierra de Pampeanas (located west and north of our study) and suggested substantial rock exhumation across the foreland region due to fl at-slab subduction and lowering of the geothermal graon June 4, 2015 lithosphere.gsapubs.org Downloaded from www.gsapubs.org | Volume 6 | Number 2 | LITHOSPHERE dient.…”

Near pure surface uplift of the Argentine Frontal Cordillera: insights from (U–Th)/He thermochronometry and geomorphic analysis

“…Data from the Chilean slope of the Andes suggest a geothermal gradient of 28-30 8C/ km south of 338S (Maksaev et al 2009). However, Andean foreland basin sediments appear to be cold with a geothermal gradient on the order of 15 8C/km (Collo et al 2011).…”

“…(c) Models of geothermal gradients for different scenarios of 0, 1, 2 and 3 km of sediment overlying the palaeosurfaces. The thermal properties of the sediments reflect the geothermal gradients reported byCollo et al (2011) and those of the granitoids are fromTurcotte & Schubert (2002) andMaksaev et al (2009). (d) Hypothetical time-temperature pathways relative to the palaeolandscape for the scenarios illustrated in (a) and (b).…”