The chronology and rotational kinematics in the South-Eastern Jaca Basin (Southern Pyrenees): Las Bellostas section

Despite the large number of magnetostratigraphic studies in South Pyrenean Basin aiming to calibrate basin chronostratigraphy and biostratigraphic scales, Eastern Jaca remains unexplored from this perspective, its relation with Ainsa is not fully understood. In work we contribute new data 950m thick Las Bellostas section, located northern hinge Balzes anticline. Well-proven primary signal (positive fold test two pseudo-antiparallel polarities) supported by numerous surroundings allow us building a reliable local polarity sequence eight magnetozones (from R1 N4). Additionally, seven samples (Nummulites Assilina) lower part section (marine environment) allows tightening Geomagnetic Polarity Time Scale (GPTS) proposing refined age model for southeastern Basin. The starts Boltaña Fm., Cuisian (Shallow Benthic Zone, SBZ11), followed sedimentary gap C22n C20n as witnessed (SBZ11 underneath hiatus SBZ16 just atop). deltaic Sobrarbe Fm. can be tracked until C19n (Late Lutetian). From point (200m) top (950m), at least, entire C18n chron recognized within molassic Campodarbe (C18n.2n-C18n.1r C18n.1n) (Bartonian) equivalent West prodeltaic Arguis marls Middle Cusian (SBZ11) Lutetian (SBZ15) stratigraphic is, part, enhanced structural position These chronostratigraphic constraints help refining W-E N-S relationships eastern This also accurately refine kinematics rotational activity External Sierras. important difference magnetic declination along neighboring paleomagnetic anticline ≈70º clockwise base non-significant top) together characterizing thrust sheet. rotation took place between chrons C20r (Middle Lutetian; 45Ma) C17 (Lower Priabonian 37-38Ma) agreement nearby structures (Boltaña, Picodel Aguila anticlines) but clearly diachronic western ones (Santo Domingo anticline). Besides, seems follow linear continuous pattern (velocity 9-11º/Ma, R: 0.83-0.96) contrast closer that show distinct velocities (i.e. Boltaña). still let open debate on basal thrust.