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Insights into the "tectonic topography" of the present-day landscape of the central Iberian Peninsula (Spain)

Tejero López, Rosa María and González Casado, José Manuel and Gómez Ortiz, David and Sánchez Serrano, Fernando (2006) Insights into the "tectonic topography" of the present-day landscape of the central Iberian Peninsula (Spain). Geomorphology, 76 . pp. 2800-294. ISSN 0169-555X

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Abstract

The landscape of today’s central Iberian Peninsula has been shaped by ongoing tectonic activity since the Tertiary. This
landscape comprises a mountain ridge trending E–W to NW–SE, the Central System, separating two regions of smooth
topography: the basins of the rivers Duero and Tajo. In this study, we explore interrelationships between topography and tectonics
in the central Iberian Peninsula. Regional landscape features were analysed using a digital elevation model (DEM). Slope gradients
and slope orientations derived from the DEM were combined to describe topographic surface roughness. Topography trendsurfaces
inferred from harmonic analysis were used to define regional topographic features. Low roughness emphasizes the smooth
nature of the basins’ topography, where surfaces of homogeneous slope gradient and orientation dominate. High roughness was
associated with abrupt changes in gradient and slope orientation such as those affecting crests, valley bottoms and scarp edges
present in the mountain chain and in some deep incised valleys in the basins. One of the applications of roughness mapping was its
capacity to isolate incised valley segments. The area distribution of incised rivers shows their prevalence in the east. On a regional
scale, the topographic surface can be described as a train of NE–SW undulations or waves of 20 km wavelength. These undulations
undergo changes in direction and interruptions limited by N–S-trending breaks. E–W and NE–SW troughs and ridges clearly mark
structural uplifts and depressions within the Central System. These structures are transverse to the compressive NW–SE stress field
that controlled the deformation of the central Iberian Peninsula from the Neogene to the present. They represent the upper crustal
folding that accommodates Alpine shortening. N–S breaks coincide with Late Miocene faults that control the basins’ sedimentation.
Further, associated palaeoseismic structures suggest the recent tectonic activity of N–S faults in the eastern part of the Tajo
Basin. Apatite fission track analysis data for this area suggest the occurrence of a significant uplift episode from 7 to 10 Ma which
induced the river incisions appearing in the roughness map. N–S and NE–SW faults could be seismogenic sources for the current
moderate to low seismic activity of the east Tajo Basin and southeast Central System. Although N–S fault activity has already been
established, we propose its significant contribution to shaping the landscape.

Item Type:Article
Uncontrolled Keywords:Digital elevation model; Topography roughness; Topography trend analysis; Central Spain; Tectonics geomorphology; Intraplate deformation
Subjects:Sciences > Geology > Geodynamics
ID Code:17147
Deposited On:19 Nov 2012 12:48
Last Modified:19 Nov 2012 12:48

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