Document Type

Article

Publication Date

8-1-2024

Department

Department of Geological and Mining Engineering and Sciences; Department of Physics

Abstract

The ca. 565 Ma Ediacaran geodynamo was highly unusual, producing an ultralow field 10 times weaker than present-day value of 8 x 1022 A m2. A ∼5 times rise in field strength is seen in time-averaged single crystal paleointensity data of ca. 532 Ma Early Cambrian anorthosites of Oklahoma (USA). The field increase could record the onset of inner core nucleation predicted by thermal evolution and numerical dynamo models. Here, we examine the renewal of the geodynamo through zircon U-Pb geochronology and single crystal paleointensity studies of plagioclase from the Chatham-Grenville syenite intrusion in the Grenville Province (Canada). U-Pb data indicate a ca. 544 Ma age and Thellier single crystal paleointensity data yield field strengths of 2.3 ± 0.6 x 1022 A m2. The new single crystal paleointensity data further support an increase in field intensity near the Ediacaran-Cambrian transition, consistent with latent heat of crystallization and release of light elements providing new energy sources to power the geodynamo upon the onset of inner core nucleation. Moreover, our new results suggest that plagioclase from syenites can yield valuable records of the geodynamo.

Publisher's Statement

© 2024 The Author(s). Published by Elsevier B.V. Publisher’s version of record: https://doi.org/10.1016/j.epsl.2024.118758

Publication Title

Earth and Planetary Science Letters

Version

Publisher's PDF

Download

Share

COinS
 
 

To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.