[Eoas-seminar] EOAS Colloquium Friday Jan 27 at 3pm

[eoas-seminar at lists.fsu.edu]

Please join us for this week's EOAS Colloquium speaker Friday Jan 27 at 3pm in 1050:
Title: Evolution of the core & paleomagnetosphere since 4 Ga: Modeling variations in dipole field strength and magnetic shielding on million-to-billion year timescales

Speaker: Dr. Richard Bono, Assistant Professor, Department of Earth, Ocean, and Atmospheric Science, FSU

Abstract
The geomagnetic field is a long-lived phenomenon that shields Earth's atmosphere from erosion by charged solar wind. Changes in atmospheric shielding may have had profound implications on the evolution of life. The geomagnetic field is generated in the liquid core through a convective process termed the geodynamo. Characterizations of how the paleomagnetic field changes on million-to-billion year timescales afford a unique opportunity for insights into core processes and conditions. Quantifying the strength of the magnetic field can be made through the collection of paleointensity estimates extracted from geologic materials. However, constructing a coherent timeline of the average dipole field is challenging, in part due to the sparsity of the paleointensity record. Here I discuss recent updates to the site-mean absolute paleointensity database PINT (www.pintdb.org<http://www.pintdb.org>; Bono et al., GJI, 2022) that includes records published through 2022. The PINT database is used to define a continuous paleomagnetic axial dipole moment model spanning 50 ka to ~4 Ga, MCADAM (Monte Carlo Axial Dipole Average Model; Bono et al., GRL, 2022). This model yields posterior predictions of axial dipole field strength and allows for estimation of the median field with associated confidence bounds. Using the MCADAM model, the paleomagnetospheric standoff distance can be estimated going back to the early Archean. Magnetic standoff evolution reveals that the strength of the magnetic atmospheric shield during the Precambrian was lower than the present day by about a factor of 2, reaching a protracted (~100 myr) minimum during the Ediacaran, before steadily climbing towards present day standoff distances. This suggests that for most of the Precambrian, atmospheric protections were weaker and perhaps more tenuous than during the Phanerozoic.

Bio
Richard Bono earned his undergraduate and graduate degrees at the University of Rochester, graduating in 2016, where he focused on using paleomagnetism gain insight into Earth's deep interior by measuring single oriented crystals. In 2018, he moved to the University of Liverpool, first as a member of the DEEP geomagnetism group and then as a Leverhulme early career fellow. There he worked to help bridge geodynamo simulations and paleomagnetic observations with an emphasis on deep time. Last year Richard joined the EOAS department here at FSU.

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--
Ming Ye, Ph.D.
Professor in Hydrogeology
Department of Earth, Ocean, and Atmospheric Science
Department of Scientific Computing
Florida State University
Tallahassee, FL 32306-4520
Office: 3015 EOAS Building (1011 Academic Way)
Phone: 850-645-4987
Cell: 850-567-4488
Email: mye at fsu.edu<mailto:mye at fsu.edu>
http://earth.eoas.fsu.edu/~mye/<https://urldefense.proofpoint.com/v2/url?u=http-3A__earth.eoas.fsu.edu_-7Emye_&d=DwMD-g&c=sJ6xIWYx-zLMB3EPkvcnVg&r=Mhyd37dJicOv2Y4TdrFHog&m=M6HuCNdoexq-OmjpdYhuF9nJRk-CZjJK4J9E8OiYagE&s=Zw0EKGXRi_xmXoT5hozL7qQqQGvB5xxO4xHJB-s1icA&e=>

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