Morphotectonics of the Concud Fault (Iberian Chain, Spain): Comparing Geomorphic and Geologic Indices of Activity of an Intraplate Extensional Fault

Lafuente, Paloma ; Lamelas, María Teresa (Universidad de Zaragoza) ; Simón, José Luis (Universidad de Zaragoza) ; Soriano, María Asunción (Universidad de Zaragoza)

Resumen: The results of geomorphic analysis of the Concud fault-generated mountain front (central Iberian Chain, Spain) are introduced into
classifications of fault activity proposed by previous authors, and compared with slip rates calculated from geologic markers. The Concud fault is an extensional structure active since the mid Pliocene times. It gives rise to a 60 to 120 m high mountain front, where footwall rocks belonging to the Triassic and Jurassic (north-western sector) and Miocene (south-eastern sector) crop out. Conspicuous triangular facets are preserved on Jurassic rocks of the central sector, while short, generally non-incised alluvial fans make the piedmont. The value of the Mountain-front sinuosity index is Smf = 1.24 for the whole mountain front (1.17 and 1.32, respectively, for both segments showing distinct footwall lithology), as obtained by the most conservative procedure. Average valley floor width/height ratios calculated for seventeen gullies crossing the fault are Vf = 0.30 (250 m upstream from the fault trace) and Vf = 0.22 (500 m upstream). These geomorphic indices, together with qualitative features of the escarpment and piedmont landscape, indicate ‘moderate’ to ‘rapid’ fault activity. The range of slip rates estimated from such morphotectonic classification (0.03 to 0.5 mm/y) encloses the range calculated from offset Late Pliocene and Pleistocene stratigraphic markers (0.07 to 0.33 mm/y) Nevertheless, the highest potential slip rate (0.5 mm/y) clearly represents an overestimate: the mountain front could give the impression of an anomalously high level of activity owing to episodic rejuvenation caused by base level drop.

Idioma: Inglés

DOI: 10.3166/ga.24.107-122

Año: 2011

Publicado en: GEODINAMICA ACTA 24, 3-4 (2011), 107-122
ISSN: 0985-3111

Factor impacto JCR: 0.471 (2011)

Categ. JCR: GEOSCIENCES, MULTIDISCIPLINARY rank: 153 / 170 = 0.9 (2011) - Q4 - T3

Tipo y forma: Article (PostPrint)

Área (Departamento): Área Geografía Física (Dpto. Geograf. Ordenac.Territ.)
Área (Departamento): Área Geodinámica Externa (Dpto. Ciencias de la Tierra)
Área (Departamento): Área Geodinámica Interna (Dpto. Ciencias de la Tierra)