Albian Black Flysch Group Deposits) and Vation of the Abundant Organic Input
Syntectonic deposits and punctuated limb rotation in an Albian submarine transpressional fold (Mutriku village, Basque-Cantabrian basin, northern Spain) L.M. Agirrezabala* Estratigra®a eta Paleontologia Saila, Euskal Herriko Unibertsitatea, 644 postakutxa, 48080 Bilbao, Spain H.G. Owen Natural History Museum, Cromwell Road, London SW7 5BD, UK J. GarcõÂa-MondeÂjar Estratigra®a eta Paleontologia Saila, Euskal Herriko Unibertsitatea, 644 postakutxa, 48080 Bilbao, Spain ABSTRACT strata and angular unconformity geome- Cenozoic foreland basins. Fewer cases have tries, temporal variation of deformation been reported from strike-slip basins. Field Deep-water syntectonic deposits and an- rates, and bedding-parallel faulting indi- and modeling studies support two contrasting, gular unconformities record the denudation cate folding by progressive limb rotation geometrically based kinematic models: instan- and deformation history of the middle Cre- and associated ¯exural slip. Local northwest- taneous limb rotation and progressive limb ro- taceous Aitzeta structure, interpreted here southeast compression is deduced in for- tation. The former model is based upon kink- as a monoclinal syncline associated with the mation of the Aitzeta syncline. The pres- band migration and displays constant dips on high-angle reverse Mutriku fault (Basque- ence of bedding-parallel oblique faulting the fold limbs (Suppe, 1983; Suppe et al., Cantabrian basin, northern Spain). Sedi- and minor drag folds suggests a component 1997). The second model produces limb ro- mentological and structural analyses, com- of right-oblique movement along the Mu- tation and increasing limb dips during growth bined with a precise chronostratigraphy triku fault. (Riba, 1976; Holl and Anastasio, 1993; Hardy based on ammonites, permit us to docu- and Poblet, 1994; VergeÂs et al., 1996; Schnei- ment in detail the history of this syncline Keywords: Albian, Basque, folding, rates, during ;0.53 m.y.
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