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| Titel |
Regional scale analysis of landform configuration with base-level (isobase) maps |
| VerfasserIn |
C. H. Grohmann, C. Riccomini, M. A. C. Chamani |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 15, no. 5 ; Nr. 15, no. 5 (2011-05-18), S.1493-1504 |
| Datensatznummer |
250012784
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| Publikation (Nr.) |
 copernicus.org/hess-15-1493-2011.pdf |
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| Zusammenfassung |
| 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 Inês lineament, identifiable in geophysical
maps but with little expression in hypsometric or topographic maps. |
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