Internal structure and kinematics of Variscan thrust sheets in the valley of the Trubia River (Cantabrian Zone, NW Spain): regional tectonic implications

被引:6
|
作者
Bulnes, M [1 ]
Marcos, A [1 ]
机构
[1] Univ Oviedo, Dept Geol, Fac Geol, E-33005 Oviedo, Spain
关键词
Variscan Belt; Asturian Ar; Cantabrian Zone; antiform-synform pair; imbricate thrust system; convergent transport directions; forward emplacement sequence;
D O I
10.1007/s005310000138
中图分类号
P [天文学、地球科学];
学科分类号
07 ;
摘要
The Variscan Belt in western Europe shows an arcuate geometry that is usually named Ibero-Armorican Arc. The nucleus of this are, known as the Asturian Arc, comprises the Cantabrian Zone which is a foreland fold and thrust belt. The Trubia River area is located in the inflexion zone of the Asturian Arc, which is a strategic structural position for unraveling the geometry and kinematics of the Variscan thrust sheets and related folds. Geological mapping, construction of stratigraphic and structural cross sections, analysis of kinematic indicators, and estimate of shortening for each cross section have been carried out. This area consists of two major antiform-synform pairs related to two imbricate thrust systems. These folds are asymmetric, tight, and their axial traces follow the trend of the Asturian Arc. They have been interpreted as fault-propagation folds. The emplacement directions measured in the Trubia River area change from north to south and converge towards the core of the Asturian Arc. The minimum shortening estimated ranges between 16.4 and 17.6 km, which corresponds to 56.9 and 59.4%. The complex crosscutting relationships between folds and thrusts suggest that, in general, the different structural units followed a forward-breaking sequence of emplacement, with some breaching and a few out-of-sequence thrusts. The analysis of the transport vectors together with the disposition of the fold axes and post-thrusting faults that deform the thrust stack are evidence of a late deformation event that is partially or totally responsible for the arcuate form of the Asturian Arc. The timing of the Asturian Arc, amount of shortening, and sequence of emplacement of the structures are in accordance with previous regional studies of the Cantabrian Zone.
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页码:287 / 303
页数:17
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