Journal
GEOLOGY
Volume 46, Issue 5, Pages 427-430Publisher
GEOLOGICAL SOC AMER, INC
DOI: 10.1130/G39938.1
Keywords
-
Categories
Funding
- National Science Foundation [EAR1647504]
- Chamberlin Postdoctoral Fellowship
- NERC [NE/P002498/1] Funding Source: UKRI
- Natural Environment Research Council [NE/P002498/1] Funding Source: researchfish
Ask authors/readers for more resources
The time of origin of Earth's dynamo is unknown. Detrital zircon crystals containing ferromagnetic inclusions from the Jack Hills of Western Australia have the potential to contain the oldest records of the geodynamo. It has recently been argued that magnetization in these zircons indicates that an active dynamo existed as far back as 4.2 Ga. However, the ages of ferromagnetic inclusions in the zircons are unknown. Here we present the first detailed characterization of the mineralogy and spatial distribution of ferromagnetic minerals in Jack Hills detrital zircons. We demonstrate that ferromagnetic minerals in most Jack Hills zircons are commonly located in cracks and on the zircons' exteriors. Hematite is observed to dominate the magnetization of many zircons, while other zircons also contain significant quantities of magnetite and goethite. This indicates that the magnetization of most zircons is likely to be dominantly carried by secondary minerals that could be hundreds of millions to billions of years younger than the zircons' crystallization ages. We conclude that the existence of the geodynamo prior to 3.5 Ga has yet to be established.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available