Isotopic and thermochronologic evidence of extremely cold lithosphere associated with a slab flattening.

COLLO, GILDA; DAVILA, FEDERICO; TEIXEIRA, WILSON; SAN´T ANNA, LUCY; NÓBILE, JULIETA; CARTER, ANDREW

BASIN RESEARCH

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2015 p. 1 - 25

0950-091X

We present mineralogic, isotopic and thermochronologic analyses on psammopelitic andtuffaceous levels from the Bermejo and Vinchina basins ? both foreland depocentres of theCentral Andes of Argentina ? that define a low-temperature regime for the crust akin to a slabshallowing and flattening process. The contents of illite in illite/smectite interstratified (I/S)show a progressive illitization into the deeper parts of both basins. The distribution of I/S iscompatible with theoretical simulations and predicted heat flow values of ca. 26 mW m2 in the8?3.4 Ma interval for the Vinchina Basin and ca. 42 mW m2 since 9 Ma for the BermejoBasin. The latter shows heat flow values that are comparable to those reported by magnetotel-luric analysis (36?40 mW m2) in agreement with previously published heat flow calculationsalong the modern Andean foreland. The Rb?Sr isochrones in psammopelites (