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

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

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