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Crustal density structure in the Spanish Central System derived from gravity data analysis (Central Spain)

Gómez Ortiz, David and Tejero López, Rosa María and Babin Vich, Rosa Blanca and Rivas Ponce, Antonio (2005) Crustal density structure in the Spanish Central System derived from gravity data analysis (Central Spain). Tectonophysics, 403 (doi:10.1016/j.tecto.2005.04.006). pp. 131-149. ISSN 0040-1951

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Abstract

Shallow and deep sources generate a gravity low in the central Iberian Peninsula. Long-wavelength shallow sources
are two continental sedimentary basins, the Duero and the Tajo Basins, separated by a narrow mountainous chain called
the Spanish Central System. To investigate the crustal density structure, a multitaper spectral analysis of gravity data was
applied. To minimise biases due to misleading shallow and deep anomaly sources of similar wavelength, first an
estimation of gravity anomaly due to Cenozoic sedimentary infill was made. Power spectral analysis indicates two
crustal discontinuities at mean depths of 31.1F3.6 and 11.6F0.2 km, respectively. Comparisons with seismic data
reveal that the shallow density discontinuity is related to the upper crust lower limit and the deeper source corresponds
to the Moho discontinuity. A 3D-depth model for the Moho was obtained by inverse modelling of regional gravity
anomalies in the Fourier domain. The Moho depth varies between a mean depth of 31 km and 34 km. Maximum depth
is located in a NW–SE trough. Gravity modelling points to lateral density variations in the upper crust. The Central
System structure is described as a crustal block uplifted by NE–SW reverse faults. The formation of the system involves
displacement along an intracrustal detachment in the middle crust. This detachment would split into several high-angle
reverse faults verging both NW and SE. The direction of transport is northwards, the detachment probably being rooted
at the Moho.


Item Type:Article
Uncontrolled Keywords:Gravity anomaly; Density crust structure; Moho undulations; Spanish Central System
Subjects:Sciences > Geology > Geodynamics
ID Code:17106
Deposited On:15 Nov 2012 10:20
Last Modified:15 Nov 2012 10:20

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