Work

Orbital Tuning of Short Reversed Geomagnetic Polarity Intervals in the Cretaceous Normal Polarity Superchron

Year: 2024

Type: article

Abstract: While the Cretaceous Normal Polarity Superchron has documented instances of brief reversed polarity intervals, the absence of accurate age determinations for such abrupt shifts poses a challenge in leveraging them as reliable reference tiepoints. This study presents a cyclostratigraphic analysis of gamma‐ray data from the DSDP Site 402A. The identification of Milankovitch cycles allowed us to construct a 405‐kyr astronomically‐tuned age model for two reversed events that occurred in the Aptian. Our results estimate an age of 117.03 ± 0.14 Ma for the Chron M”‐1r” or ISEA and 116.17 ± 0.14 Ma for reversal “2,” with timespans of ∼20 and ∼10 kyr, respectively. Sedimentation patterns are influenced by orbital eccentricity cycles with an average sedimentation rate of 5 cm/kyr. The short time intervals related to these reversals exposes the difficulty in their detection in cores through paleomagnetic analysis as well as in deep‐tow surveys.

Source: Geophysical Research Letters

DOI: 10.1029/2024gl110530

Authors: J. M. F. Ramos, J. F. Savian, D. R. Franco, M. F. Figueiredo, C. G. Leandro, F. Frontalini

Institutions: Universidade Federal do Rio Grande do Sul, Petrobras (Brazil), National Observatory, University of Urbino

Language: English

Topic: Geomagnetism and Paleomagnetism Studies

Subfield: Molecular Biology

Field: Biochemistry, Genetics and Molecular Biology

Domain: Life Sciences

Open Access status: gold

Estimated APC paid: $2,900

Funders: Conselho Nacional de Desenvolvimento Científico e Tecnológico, Petrobras, Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro