Formation of orogen-perpendicular thrusts due to mechanical contrasts in the basal décollement in the Central External Sierras (Southern Pyrenees, Spain)
2009 (English)In: Journal of Structural Geology, ISSN 0191-8141, Vol. 31, no 5, 523-539 p.Article in journal (Refereed) Published
Two series of analogue models are used to explore the effect of ductile-frictional contrasts of the basal decollement on the development of oblique and transverse structures during thin-skinned shortening. These models simulate the evolution of the Central External Sierras (CES; Southern Pyrenees, Spain), which constitute the frontal emerging part of the southernmost Pyrenean thrust. The CES are characterised by the presence of N-S to NW-SE anticlines, perpendicular to the Pyrenean structural trend and developed in the hanging-wall of the thrust system. They detach on unevenly distributed Triassic materials (evaporitic-dolomitic interfingering). The models simulated the effect of adjacent ductile versus frictional decollements during shortening. Model Series A tests the thickness ratio between overburden and the ductile layer, whereas model Series B tests the width (perpendicular to the shortening direction) of frictional decollement. Model results confirms that deformation reaches further in areas detached on a ductile layer whereas above frictional decollement areas, shortening is accommodated by additional uplift and penetrative strain. This replicates the structural style of the CES: higher structural relief of N-S anticlines with regard to orogen-parallel structures, absence of a representative ductile decollement in the core, plunging towards the hinterland and foreland-side closure not thrusted by the South Pyrenean thrust.
Place, publisher, year, edition, pages
2009. Vol. 31, no 5, 523-539 p.
Analogue modelling, External Sierras, Southern Pyrenees, Pico del Aguila, Detachment, Ductile deformation, Brittle deformation
Earth and Related Environmental Sciences
IdentifiersURN: urn:nbn:se:uu:diva-105497DOI: 10.1016/j.jsg.2009.03.011ISI: 000267182900007OAI: oai:DiVA.org:uu-105497DiVA: diva2:221392