An excellently exposed outcrop of Carboniferous rocks in the Cantabrian Zone (Variscan foreland fold-thrust belt in NW Iberia) displays fault-bend, fault-propagation and detachment folds. To unravel the parameters that controlled their development, we constructed detailed cross-sections and analysed them. Detachment folds exhibit the greatest amounts of layer-parallel/bulk strain, forelimb dip and forelimb/hinge thickening and the lowest interlimb angle, whereas fault-bend folds have the lowest values except for the interlimb angle, with fault-propagation folds exhibiting intermediate values. The forelimbs of all these folds show some strain and thickening, and the detachment folds also show thickening and strain in the hinge area. Mechanical stratigraphy was determined to be the main controlling factor on the fold/thrust style; ramp folds developed in thick-bedded, isotropic, relatively strong and brittle rocks, whereas detachment folds developed in a thin-bedded, anisotropic, relatively weak and ductile unit. Competent rocks and smooth bedding surfaces induced fault-bend folding, whereas less competent and rough bedding surfaces favoured fault-propagation folding. The main detachments are located at the boundaries between mechanical units with substantial changes in their mechanical properties. The size of the structures depends on the occurrence of a basal detachment, variety of lithologies with different competences and smoothness of bedding surfaces. 2014). Fault-bend folds (Rich, 1934) form as a result of the movement of a fault block along a non-planar fault surface, which causes the bending of the fault block, and therefore, the formation of the fold. Although they usually develop in the hangingwall, they can also develop in the footwall or in both fault blocks. Fault-propagation folds (Dahlstrom, 1970) are formed contemporaneously with the propagation of a fault in a ramp situation through a series of strata, so that the shortening causes the formation of a fold near its termination. Detachment or décollement folds (Chamberlin, 1910), unlike fault-bend and fault-propagation folds, are not associated with a fault ramp, but form in relation to a thrust parallel to the layers (detachment). They can be generated near the thrust tip or in any other area along the thrust if a sharp decrease in the amount of displacement occurs. Detachment folds may be limited by a lower detachment, by an upper one or by both. These three styles of fold/thrust interaction exhibit several distinguishing features in terms of: a) Fold geometry. Assuming that thrust faults involve undeformed rocks and subsequent deformation is absent, fault-bend folds are usually open structures with gently dipping limbs, fault-propagation folds are usually tighter structures with a long, gently dipping backlimb and a shorter, steeply dipping forelimb, and detachment folds exhibit all sorts of geometries. b) Fault geometry. Fault-bend and fault-propagation folds are ramp folds, whereas detachment folds are unrelated to thrust ramps. c) Fault tip. F...
Acid rain is a problem that despite efforts to reduce atmospheric pollution, continues to impact not only countries where there is a high production of pollutants, but also transboundary areas to which the pollutants are transported. In addition to its effects on human health, there are also the effects on infrastructure and the consequences that this entails. This study on the effect of rain and acid rain on calcareous materials highlights the need for protection of buildings constructed from these materials, many of which are part of the cultural heritage. The effects caused by rain and acid rain were studied using a rain simulator whose features allow the simulation of natural conditions as realistically as possible. In the same way, the effect of a coating synthesized from nanomaterials, which has been shown to serve as protection against the degradation caused by rain, was analyzed. In addition to a long-lasting protection of the stone material, this type of coating avoids the need for the replacement of elements and the recurrent cleaning of degraded parts. It also avoids the accumulation of parts on the ground, the transport of personnel, work materials and raw materials, thereby contributing to the reduction of the carbon footprint and water savings, which in turn reduces the production of pollutants that cause acid rain.
The importance of understanding the effects of rainfall on different materials over time makes it essential to carry out controlled tests to reduce analysis time. Rainfall simulators have been in use for decades and have been implemented as technology and knowledge of the physical behavior of water advanced. There are two main types of rainfall simulators: gravity simulators and pressure simulators. In the former, the drop velocity is normally smaller than the terminal velocity reached by natural droplets; in the latter, the drop size is too small to be representative and has far more speed than the natural speed for those sizes. To solve this problem, a simulator has been developed where the terminal velocity of the raindrops is reached and the drop size can be varied by different nozzles of variable sizes, adapting it to the conditions of a given region. In this study, conditions similar to the rainfall conditions of the city of León have been achieved. This paper presents the design of a rainfall simulator that recreates different rainfall conditions and rainwater composition and its calibration process.
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