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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Regional scale analysis of landform configuration with base-level (isobase) maps

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Grohmann, C. H. [1] ; Riccomini, C. [2] ; Chamani, M. A. C. [3]
Total Authors: 3
[1] Univ Sao Paulo. Inst Geosci
[2] Univ Sao Paulo. Inst Geosci
[3] Univ Sao Paulo. Inst Geosci
Total Affiliations: 3
Document type: Journal article
Source: HYDROLOGY AND EARTH SYSTEM SCIENCES; v. 15, n. 5, p. 1493-1504, 2011.
Web of Science Citations: 15

Base-level maps (or ``isobase maps{''}, as originally defined by Filosofov, 1960), express a relationship between valley order and topography. The base-level map can be seen as a ``simplified{''} version of the original topographic surface, from which the ``noise{''} of the low-order stream erosion was removed. This method is able to identify areas with possible tectonic influence even within lithologically uniform domains. Base-level maps have been recently applied in semi-detail scale (e.g., 1:50 000 or larger) morphotectonic analysis. In this paper, we present an evaluation of the method's applicability in regional-scale analysis (e.g., 1:250 000 or smaller). A test area was selected in northern Brazil, at the lower course of the Araguaia and Tocantins rivers. The drainage network extracted from SRTM30\_PLUS DEMs with spatial resolution of approximately 900 m was visually compared with available topographic maps and considered to be compatible with a 1:1,000 000 scale. Regarding the interpretation of regional-scale morphostructures, the map constructed with 2nd and 3rd-order valleys was considered to present the best results. Some of the interpreted base-level anomalies correspond to important shear zones and geological contacts present in the 1:5 000 000 Geological Map of South America. Others have no correspondence with mapped Precambrian structures and are considered to represent younger, probably neotectonic, features. A strong E-W orientation of the base-level lines over the inflexion of the Araguaia and Tocantins rivers, suggest a major drainage capture. A N-S topographic swath profile over the Tocantins and Araguaia rivers reveals a topographic pattern which, allied with seismic data showing a roughly N-S direction of extension in the area, lead us to interpret this lineament as an E-W, southward-dipping normal fault. There is also a good visual correspondence between the base-level lineaments and geophysical anomalies. A NW-SE lineament in the southeast of the study area partially corresponds to the northern border of the Mosquito lava field, of Jurassic age, and a NW-SE lineament traced in the northeastern sector of the study area can be interpreted as the Picos-Santa Ines lineament, identifiable in geophysical maps but with little expression in hypsometric or topographic maps. (AU)

FAPESP's process: 09/17675-5 - Digital terrain analysis and remote sensing applied to geomorphometric characterization of landforms
Grantee:Carlos Henrique Grohmann de Carvalho
Support type: Regular Research Grants