Kinematics of Burial Remagnetizations in Fold-and-Thrust Belts: A Case Study From the South Pyrenean Foreland Basin (NE Spain)

Abstract

[EN]This study investigates two burial‐related remagnetizations in the Jaca–Pamplona foreland basin (Southern Pyrenees): one with dual polarity and a positive reversals test, and another with only reverse polarity. These components, labeled C3 and C4 based on their mean unblocking temperatures, were identified from a paleomagnetic analysis of 142 sites in Eocene turbidites of the Hecho Group. Component C3 shows unblocking temperatures of 250°C–350°C, systematic reverse polarity, and a predominantly post‐folding timing. Component C4 exhibits unblocking temperatures of 250°C–550°C, dual polarity and a mainly syn‐to postfolding acquisition. The spatial distribution of C4 polarity defines WNW–ESE bands parallel to structures and younging southward. The acquisition of C4 is interpreted as a chemical remagnetization triggered by progressive burial driven by combined sedimentary and tectonic loading that increased temperatures (up to ∼250°C in the deeper northern sectors, according to previous paleotemperature studies). This thermal evolution promoted authigenic, stable single‐domain magnetite growth, beginning during the Lutetian (chron C20) and probably ending in the Rupelian (chrons C11‐C10) as uplift and exhumation progressed. In contrast, the reverse polarity and post‐folding behavior of component C3 suggest a mixed origin involving both chemical remagnetization and a thermoviscous overprint during the long chron C12r (Rupelian), contemporaneous with the youngest reverse C4 band and preceding the final exhumation of the basin. These findings highlight the complex interplay among tectonics, sedimentation, and chemical remagnetization processes in the South Pyrenean foreland, providing new insight into the timing and kinetics of remagnetization in fold‐and‐thrust belts.