TECTONOSTRATIGRAPHIC HISTORY OF THE NEOGENE MAIMARA BASIN, NORTHWEST ARGENTINA.

GALLI, CLAUDIA; COIRA, BEATRIZ; ALONSO, RICARDO; IGLESIA LLANOS, MARÍA P.; PREZZI, CLAUDIA BEATRIZ; MAHLBURG KAY, SUZANNE

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2016 vol. 72 p. 137 - 158

0895-9811

This paper presents the tectonostratigraphic evolution of the Maimará Basin and explores the relationship between the clastic sediments and pyroclastic deposits in the basin and the evolution of the adjacent orogeny and magmatic arc. The sedimentary facies in this part of the basin include, in ascending order, an ephemeral fluvial system, a deep braided fluvial system and a medial to distal ephemeral fluvial system. We interpret the Maimará Basin as a foreland basin with a two stage evolution history. Stage 1 extended from 7 to 6.4 Ma and included accelerated tectonic uplift in the source areas, and it corresponds to the ephemeral fluvial system deposits. Stage 2, which extended from 6.4 to 4.8 Ma, corresponds to a tectonically quiescent period and included the development of the deep braided fluvial system deposits. The contact between the Maimará and Tilcara formations is always characterized by a regional unconformity and, in the study area, also shows pronounced erosion.The geochemical characteristics of the tuff intervals in the Maimará Formation indicate two areas of provenance of the ashes; the Guacha, Pacana and Pastos Grandes calderas, which are located 200 to 230 km west of the study area, are the most representative, and the Cerro Galán caldera (Merihuaca Ignimbrite), which is located 290 km to the south-southwest, is the subordinate provenance area. The distinctive geochemical characteristics are excellent tools to reconstruct the stratigraphic evolution of the Neogene Maimará foreland basin from 6.4 to 4.8 Ma.