Landscape evolution in the Guañacos fold and thrust belt (37° S): Insights from geomorphological and morphometric analysis. (November 2021)

• Record Type: Journal Article
• Authors: Jagoe, Lucía; Sagripanti, Lucía; Colavitto, Bruno; Folguera, Andrés
• Is Part Of: Journal of South American earth sciences. Volume 111(2021)
• Publication Date: 2021-11
• Subjects: Active tectonics -- Surface modeling -- Glacial erosion -- Drainage analysis -- Morphometric indices; Geology -- Latin America -- Periodicals; Earth sciences -- Latin America -- Periodicals; Geology -- Antarctica -- Periodicals; Earth sciences -- Antarctica -- Periodicals; Geology -- Caribbean Area -- Periodicals; Earth sciences -- Caribbean Area -- Periodicals; Géologie -- Amérique latine -- Périodiques; Sciences de la terre -- Amérique latine -- Périodiques; Géologie -- Antarctique -- Périodiques; Sciences de la terre -- Antarctique -- Périodiques; Géologie -- Caraïbes (Région) -- Périodiques; Sciences de la terre -- Caraïbes (Région) -- Périodiques; Earth sciences; Geology; Antarctica; Caribbean Area; Latin America; Periodicals; 550.5
• DOI: 10.1016/j.jsames.2021.103484
• Languages: English
• ISSNs: 0895-9811

Abstract

Abstract: The Guañacos fold and thrust belt, in the northern Neuquén Andes (37°-38°S; 70°30′-71°10′W), has been studied by many researchers focusing on the Quaternary tectonic activity, from a morphological to a structural perspective. Additionally, this portion of the Andes is quite peculiar due to the numerous geomorphic processes coeval with neotectonic, such as volcanic, mass-wasting, glacial, and fluvial processes. However, it is not yet clear the impact of each one of these processes on landscape evolution. This paper reviews the evidence for the geomorphological modeling of the Guañacos belt and analyses the effects of the various actuating processes over the drainage network, implementing different and novel morphometric indices. We studied the hypsometry of the main basins in the area and identified knickpoints of the trunk of each basin from the stream profile slope-area plot. Besides, we applied morphometric indices such as the k sn and the χ for all catchments to evaluate the state of equilibrium of the stream network and basin divides. Our results show disequilibrium conditions over the entire fluvial network consistent with rockslide deposits and active structures. This study also discusses the usefulness of the applied morphometric indices in an area with low neotectonic slip-rates, great mass-wasting deposits, and glacial erosion. Findings in this matter showed substantial differences in the indices' response whether the analyzed basin was primarily glacial or fluvial carved. Taken together, results in the Guañacos fold and thrust belt suggest that the glacial erosion and the subsequent rockslide deposits are the prime agents for landscape modeling, making it unable to acknowledge the effect of Quaternary tectonic activity. Only when they are absent is it possible to recognize the neotectonic signature over the drainage. Highlights: Landscape evolution in Southern Central Andes between 37° and 38° S was analyzed. K sn and χ maps yield disequilibrium conditions in the stream network. Slope-area plot reveal knickpoints and concavity more affected by rockslides deposits. Glacial erosion and rockslide deposits obscure the neotectonic' effects over drainage. Geomorphic and tectonic processes influence morphometric indices.