Evaluation of Paleomagnetic Bias in Ediacaran Global Paleogeographic Reconstructions

• Published in: Geophysical research letters Vol. 49; no. 24
• Main Authors: Wu, Lei, Murphy, J. Brendan, Nance, R. Damian
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 28.12.2022
• Subjects: Bias; Constraint modelling; Geological data; Geological time; Geology; Geomagnetic variations; Magnetism; Modelling; Palaeomagnetism; Paleomagnetism; Precambrian; Provenance; South Pole; Tectonics; Tracers
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2022GL100405

Paleogeographic models provide first‐order insights into Earth's tectonic evolution in deep geologic time. However, there is a lack of objective metrics to distinguish between rival models. Using a recent compilation of reliable Precambrian paleomagnetic data, we quantify the extent of paleomagnetic compliance of existing Ediacaran global reconstruction models. We determine spherical arc distances between modeled paleopositions of the geographic South Pole and reconstructed coordinates of all paleopoles from a continent acquired at various times. We identify significant paleomagnetic bias for a reconstructed location of a continent if arc distances of the majority of high‐quality paleopoles with reliable age constraints are greater than their standard errors at the 95% confidence interval. Our study provides quantifiable measures of paleogeographic bias that allows researchers to make informed decisions when selecting among existing global models as a foundation for interpreting their geologic data. Plain Language Summary Paleogeographic reconstructions, often presented as black‐box models of the paleolocations of continents, are typically constructed by minimizing paleomagnetic bias while satisfying geologic constraints. Such paleogeographic models are created to fit some informed selection of paleomagnetic and geologic data. However, underfitting (i.e., ignoring specific paleopoles) of paleogeographic models, especially where paleomagnetic data are sparse, is potentially problematic as models may not capture apparent, ancient geomagnetic variations. Geologic observations such as paleoenvironmental, biogeographic, and sedimentary provenance tracers, are commonly used to justify underfitting, but can inadvertently result in paleogeographic models with large paleomagnetic bias. Furthermore, interpretations of geologic constraints are often equivocal or controversial, yielding multiple plausible continental paleopositions. Here we adopt simple metrics to detect the paleomagnetic bias inherent in a selection of recently Ediacaran paleogeographic models, each purported to satisfy first‐order paleomagnetic and geologic (typically paleoenvironmental and tectonostratigraphic) constraints. These simple metrics will allow researchers to assess the trade‐off between paleomagnetic error and geological plausibility inherent in individual paleogeographic models. Key Points Paleomagnetic bias of a continental reconstruction can be detected from the extent of compliance to available robust paleomagnetic poles We propose a simple workflow to objectively quantify paleomagnetic bias in reconstruction models We evaluate the paleomagnetic bias of six competing Ediacaran global reconstruction models