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Published June 15, 2021 | Published + Supplemental Material
Journal Article Open

A Late Cretaceous true polar wander oscillation


True polar wander (TPW), or planetary reorientation, is well documented for other planets and moons and for Earth at present day with satellites, but testing its prevalence in Earth's past is complicated by simultaneous motions due to plate tectonics. Debate has surrounded the existence of Late Cretaceous TPW ca. 84 million years ago (Ma). Classic palaeomagnetic data from the Scaglia Rossa limestone of Italy are the primary argument against the existence of ca. 84 Ma TPW. Here we present a new high-resolution palaeomagnetic record from two overlapping stratigraphic sections in Italy that provides evidence for a ~12° TPW oscillation from 86 to 78 Ma. This observation represents the most recent large-scale TPW documented and challenges the notion that the spin axis has been largely stable over the past 100 million years.

Additional Information

© The Author(s) 2021. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. Received 25 June 2020; Accepted 10 May 2021; Published 15 June 2021. Alessandro Montanari of the Osservatorio Geologico di Coldigioco provided invaluable field support and local geological knowledge. David Bice helped identify the critical outcrop at Apiro Dam. Assistance in the field was provided by Alec Brenner, Emily Carter, Stefan Farsang, Harry Golash, Hima Gudipati, Jessica Heringer, Harrison Miller, Alessandro Montanari, Karen Paczkowski, and Brian Penserini. Laboratory measurements were conducted by Jacob Abrahams, Michael Grappone, Garima Gupta, Marco Cruz-Heredia, Valerie Pietrasz, Kirby Sikes, and Lewis Ward. R.N.M. and J.L.K. were supported by NSF Geophysics grant EAR-1114432. R.N.M. was also supported by the the National Natural Science Foundation of China (No. 41890833 and 41772192) and the Institute of Geology & Geophysics, CAS, grant no. IGGCAS-201905. This is a contribution to the International Geoscience Programme 648. Data availability: The palaeomagnetic data from this study are available in the online content of this paper and from the Open Science Framework (https://osf.io/hqzdy/?view_only=2c5ab4f569d842b8a7678b8bfd1a27dd). Magnetometer measurements are available from the corresponding author upon reasonable request. Code availability: Rock magnetic data were analyzed using the RAPID Matlab scripts17 available at https://sourceforge.net/projects/paleomag/. Author Contributions: R.N.M., C.J.T., D.A.D.E., and J.L.K. designed the study. R.N.M., C.J.T., S.P.S., R.C., and J.L.K. conducted the field work. R.C. conducted the biostratigraphy. S.P.S. conducted the rock magnetic experiments. T.Y. conducted the FORC experiment. R.N.M., C.J.T., D.A.D.E., and S.P.S. conducted the palaeomagnetic and palaeogeographic analysis. R.N.M. wrote the manuscript with input from all authors. The authors declare no competing interests. Peer review information: Nature Communications thanks William Sager and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Peer reviewer reports are available.

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