Inheritance in shortening transfer and kinematics in fold-and-thrust belts: Revisiting the structure of the Jaca Basin, Southern Pyrenees

Muñoz, Josep Anton ; Izquierdo-Llavall, Esther ; Santolaria, Pablo ; Toro, Rosibeth ; Pueyo, Emilio L. ; Casas, Antonio M. (Universidad de Zaragoza) ; Granado, Pablo

Resumen: This study revisits the structural evolution of the Jaca Basin in the Southern Pyrenees through a revision of the works done in the study area combined with a detailed analysis of geological and subsurface data, culminating in a new balanced cross-section. Our findings demonstrate that the propagation of the deformation into the foreland, from the basement to the cover, is heavily influenced by the uneven distribution of the Upper Triassic salt layer, at the base of the deformed Mesozoic-Paleogene succession, and the reactivation of Permian and Triassic extensional faults. This has led to a distinctive non-cylindrical fold-and-thrust belt with frictional and viscous domains displaying different structural styles. In the frictional domains, where Triassic salt is absent, high-angle thrust systems with a short wavelength involve both the basement and overlying strata, resulting in tight folds and related cleavage. In contrast, in the viscous domains where salt is preserved, deformation structures involving the cover succession are decoupled from the basement and propagate further into the foreland. Nevertheless, structures of both domains, independently of their location and geometry, tended to connect and link, resulting into an intricate thrust system with the development of numerous oblique structures. These oblique structures are further accentuated by the reactivation of inherited Permian and Triassic extensional faults, primarily involving basement thrusts. Differences in the topography between the frictional and viscous domains have also influenced the deposition and routing of syntectonic sediments, which in their turn have also determined the thrusting sequence. The evolutionary sequence of thrusting initiated in the late Ypresian and continued into the early Neogene. Contrary to previous models that suggested simply piggy-back propagation, our findings indicate a complex pattern of synchronous and break-back thrusting sequences with continuous forward propagation of the deformation. Detailed field work supports thrusting ages older than previously thought and indicates a greater amount of shortening (approximately 58 km) than earlier estimates. This comprehensive integration of surface and subsurface data challenges traditional interpretations and provides new insights into the structural evolution of the Southern Pyrenees. Our study highlights the importance of considering three-dimensional structural interactions in understanding tectono-sedimentary relationships. These insights into the complex structural geometry of the Jaca Basin enhance our understanding of similar salt-bearing fold-and-thrust belts globally, such as Zagros, Western Alps, Calcareous Alps, among many others, emphasizing the critical role of inherited geological features and uneven salt distribution in shaping orogenic systems.

Idioma: Inglés

DOI: 10.1016/j.earscirev.2025.105237

Año: 2025

Publicado en: Earth-Science Reviews 270 (2025), 105237 [37 pp.]
ISSN: 0012-8252

Financiación: info:eu-repo/grantAgreement/ES/AEI/PID2020-117598GB-I00
Financiación: info:eu-repo/grantAgreement/ES/MICINN/PID2019-104693GB-I00

Tipo y forma: Article (Published version)

Área (Departamento): Área Geodinámica Interna (Dpto. Ciencias de la Tierra)