Thermochronometry unveils ancient thermal regimes in the NW Pampean Ranges, Argentina: From Mesozoic rifting to Miocene flat-slab subduction

EZPELETA, MIGUEL; PARRA, MAURICIO; COLLO, GILDA; WUNDERLIN, CECILIA; BORREGO, ANGELES G.; SOBEL, EDWARD R.; GLODNY, JOHANNES

BASIN RESEARCH

WILEY-BLACKWELL PUBLISHING, INC

Año: 2022 vol. 34 p. 1983 - 2012

0950-091X

Reconstructing thermal histories in thrust belts is commonly used to infer the age and rates of thrusting and hence the driving mechanisms of orogenesis. In areas where ancient basins have been incorporated into the orogenic wedge, a quantitative reconstruction of the thermal history helps distinguish among potential mechanisms responsible for heating events. We present such a reconstruction for the Ischigualasto-Villa Unión basin in the western Pampean Ranges of Argentina, where Triassic rifting and late Cretaceous-Cenozoic retroarc foreland basin development has been widely documented, including Miocene flat-slab subduction. We report results of organic and inorganic thermal indicators acquired along three stratigraphic sections, including vitrinite reflectance and X-ray diffractometry in claystones and new thermochronological [(apatite fission-track and apatite and zircon [U-Th]/He)] analyses. Despite up to 5 km-thick Cenozoic overburden and unlike previously thought, the thermal peak in the basin is not due to Cenozoic burial but occurred in the Triassic, associated with a high heat flow of up to 90 mWm−2 and