. Uplift sequence of the Andes at 30°S: insights from sedimentology and U/Pb dating of synorogenic deposits

SURIANO, J., MARDONEZ, D., MAHONEY, J.B., MESCUA, J.F., GIAMBIAGI, L., KIMBROUGH, D. Y LOSSADA, A.,

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2017 vol. 75 p. 11 - 34

0895-9811

The South Central Andes at 30 S represent a key area to understand theAndes geodynamics as it is in themiddle of the flat slab segment and all the morphotectonic units of theCentral Andes are well developed.This work is focused in the proximal synorogenic deposits of the WesternPrecordillera, in the La Trancavalley, in order to unravel the uplift sequence of this belt. Nine faciesassociations were recognized; mostof them represent piedmont facies with local provenance from Precordilleraand were deposited in thewedge-top depozone, as is expected for proximal sinorogenic deposits.However there are intercalationsof transference fluvial systems, which show mixed provenance indicatingthat Permo-Triassic igneousrocks were already exposed to the west (Frontal Cordillera). There are alsolacustrine deposits which areinterpreted as the result of damming by fault activity at east of thestudied basin.Finally, two maximum depositional ages at ca. 11 Ma and 8 Ma of thesedeposits indicate that the onsetof uplift of the Precordillera at 30 S is little older than 11 Ma. Thesedata change two previous ideas aboutthe evolution of the Precordillera: its uplift at 30 S is younger thanproposed by previous works and it isnearly synchronous along strike.