A general overview of gondwana landscapes in Argentina

Abstract

Gondwana Landscapes in Argentina were already identified by Juan Keidel and Walther Penck at the beginnings of the twentieth century, as well as by other geologists and naturalists of the different European schools that worked in this country. These studies were continued at a very good level in Brazil, thanks to the work of Lester C. King, later on intensively followed by João José Bigarella. However, these concepts gradually disappeared from the Argentine geological scene, dominated by the influence of American geomorphologists, and particularly William Thornbury, who doubted the existence of such ancient landforms, when one of the paradigms of the time was that “practically there is no landscape older than the Pleistocene." These landforms are the result of the process of both deep chemical weathering, developed in very stable tectonic and climatic environments, under hyper-tropical climates, and pediment processes in semiarid to humid environments. The Gondwana Landscapes or their fragmented remnants have been recognized in Argentina, from north to south, in the basaltic hills of the province of Misiones; the Sierras Pampeanas of the provinces of Catamarca, La Rioja, and San Juan; the Sierras Chicas, Sierras Grandes, and Sierra Norte of Córdoba province; the Sierras de San Luis, the Sierra Pintada, or San Rafael Block of Mendoza province; the Sierras de Tandil, Sierra de la Ventana, and the Pampa Interserrana of Buenos Aires province; the Sierras de Lihuel Calel of the province of La Pampa; the Somuncurá or Northern Patagonian Massif in the provinces of Río Negro and Chubut; the Deseado Massif of Santa Cruz province; and the Malvinas-Falklands archipelago. In other regions of Argentina, these surfaces have been downwarped in tectonic basins and are covered by sedimentary and/or volcanic units of various ages. The ages for the development of the Gondwana Landscapes have been estimated in between the Middle Jurassic and the Paleogene. The Argentine Gondwana Landscapes were uplifted, fragmented, and eroded during the Middle to Late Tertiary. They have remained as mute testimony of the past above extensive pediplains and piedmont deposits, as climates and environments became more arid and cooler, approaching the present conditions.