The neotectonic origin of the natural dam of Mar Chiquita, Córdoba, Argentina
by
Ricardo Mon
Universidad de Tucumán, Argentina
Coauthors: Antonio A. Gutierrez (Universidad de Tucumán, Argentina)

The Mar Chiquita saline lake is located in the deepest part of the largest endorreic basin of South America. It now has a surface of 6000-6500 km2. The tectonic depression, where the lake is located , has an assymetric cross section. To the west are the Sierras Pampeanas foothills with altitudes near 500 m and to the east a 150 m topographic high , with its west border bounded by a buried young fault (Mar Chiquita fault). The main tributary of the lake is the Dulce River which flows from north to south and collects the water from a 54000 km2 basin. The southward river flow was impeded by an obstacle wich closed the Dulce valley, generating the impounding of Mar Chiquita. Other rivers like the Primero and Segundo, flowing from southwest, also discharge into the Laguna Mar Chiquita. It seems that a generalized tectonic uplift and northward tilting of the area located southward of Mar Chiquita generated the obstacle impeding the normal flow of the rivers. This uplift, related probably to a large continental arching, has regional extension; it also affected the southeastern part of the Sierras Pampeanas. There are no precise data about the age of the uplifting generating the Mar Chiquita dam, but the dry valley of the Dulce River situated southward of Mar Chiquita, still visible in the satellite images, is a good indicator of the extreme youth of the impounding. The dry valley coincides with the Cañada Antonio ravine and it is clear that the continuation of this valley is the Carcarañá River and that, before the impounding, the Dulce River discharged directly into the Paraná. The impounding of the Dulce River had pronounced enviromental consequences generating upstream of the lake large low wetlands, where special vegetation, fauna and a different microclimate developed.

Date received: November 25, 2004

Copyright © 2004 by the author(s). The author(s) of this document and the organizers of the conference have granted their consent to include this abstract in Atlas Conferences Inc. Document # caod-54.