No Late Cretaceous true polar wander oscillation and implications for stability of Earth relative to the rotation axis

Abstract

Knowledge of Earth's stability with respect to the spin axis sets boundary conditions for understanding the deep mantle and interpreting records of past climate. Recently it has been argued that the solid Earth rotated by 12∘, and then rotated back, 86 to 78 million years ago. Herein we reanalyze the paleomagnetic data and report new rock magnetic analyses, from the Scaglia Rossa limestone of Italy on which this true polar wander (TPW) was based. We find that these data record an unrecognized secondary magnetization carried by authigenic hematite. This overprint has a differential angular effect on the normal and reversed polarity primary magnetizations, creating biased directions. This bias, together with probable tectonic and sedimentary slide rotations, creates false polar wander signals. The recognition of these artifacts serves as a cautionary tale and indicates that the null hypothesis of no large TPW since the Late Cretaceous cannot be rejected. This stability is fundamentally different from that of other planetary bodies which have undergone large polar wander, and provides the framework for Earth's climate history. Because of uncertainties in paleolongitude and geomagnetic field morphology, the unambiguous definition of terrestrial TPW deeper in time remains elusive.