Spatio-temporal variation of fluid flow behavior along a fold: The Bóixols-Sant Corneli anticline (Southern Pyrenees) from U–Pb dating and structural, petrographic and geochemical constraints

This study integrates field structural data, petrographic and geochemical (? 18 O, ? 13 C, ? 47 , 87 Sr/ 86 Sr, elemental composition) analyses U–Pb dating of calcite veins cutting the Bóixols-Sant Corneli anticline (Southern Pyrenees) in order to date investigate spatio-temporal relationships between fluid flow fold evolution. E-W trending grew from Late Cretaceous Paleocene at front Bóixols thrust sheet deforming pre-growth growth sedimentary sequences. reveals late Miocene deformation ages, which agree with age strata deposition sequence interpreted microstructural data. Dates coeval (71.2 ± 6.4 56.9 1.4 Ma) postdating (55.5 1.2 27.4 0.9 Upper are record: (i) during emplacement, (ii) tightening southern tectonic transport South-Central Pyrenean Unit. Other ages (20.8 9.0 4.6 postdate folding event have been associated collapse anticline. The geochemistry indicates that behavior varied across through its growth, showing a compartmentalized system. In hinge upper Santonian middle Campanian syn-orogenic along footwall thrust, similar features all cements host rocks point towards locally-derived or well-equilibrated Contrarily, large faults such as limbs, vein different scenario. Cements yielded lightest O values, ?8 ?14 ‰VPDB, variable enrichment composition . is migration fluids, fault zones, evolved distinct origins. limbs exhibit C ?6 ‰VPDB ?10 + 2 respectively, lowest Sr contents precipitation temperatures, suggesting recorded infiltration evolution meteoric waters. paleohydrological system was restricted sheet. Triassic evaporitic basal detachment likely acted lower barrier, preventing input fluids deeper parts crustal provides well-constrained absolute timing fracturing basin inversion highlights suitability geochronology refine fractures their sequential orogenic belts. • Twenty-three new U-Pb dates provide an preserves pre-, syn- post-folding do not symmetrical orientation respect axis, important implications for interpretation fold-fracture systems. We further constrain duration positions anticline, evidencing only involves sourced above levels, may act boundary system, belt.