Planation Surfaces of Central Western 1 Argentina

MARCELO ZÁRATE; FOLGUERA ALICIA

Gondwana Landscapes in southern South America

Springer

Lugar: Dordrecht; Año: 2014;

Abstract The region of central western Argentina is situated in a complex 4 geological and tectonic setting with transitional features between major 5 environmental, tectonic, and geomorphological domains. Preserved remnants of 6 planation surfaces, which form the summit of major geological units, occur as 7 discontinuous and isolated exposures with a remarkable geographical distribution 8 along 600 km (33ı?39ı S). The main goal of this chapter is to summarize the 9 available information and describe the main features and geological context of the 10 planation surfaces preserved in the areas of the San Rafael block, Payenia, the 11 Chical-có plain, and the Chadileuvú block situated in the southern part of Mendoza 12 and western La Pampa provinces, central western Argentina. The common feature 13 of the areas under analysis is the occurrence of remnants of planation surfaces 14 at different altitudes which cut across bedrock of different composition (igneous, 15 metamorphic, and sedimentary units) and varied age ranging from the Middle 16 Proterozoic (Grenvillian age) to Middle Triassic continental sedimentary rocks. 17 The development may have begun in the Triassic, before the Gondwana breakup 18 and more than one planation surface might be present. During the Late Miocene 19 synorogenic deposits covered the planation surface at the San Rafael block, very 20 likely Payenia, and the Chical-có plain; no conclusive evidence is available in the 21 area of the Chadileuvú block. As a result of tectonic activity (circa 7?6 Ma?), 22 the region was fractured, differentially uplifted, and started a general exhumation 23 process that partially removed the Late Miocene sedimentary cover from the San 24 Rafael block and the eastern margin of Chical-có plain.