Earth’s magnetic field varies in both space and time. Characterizing and understanding those variations can help us to understand the processes in Earth’s core that generate the magnetic field. They can also help to provide constraints on planetary differentiation, inner core nucleation, and atmospheric evolution. Records of the Earth’s field can be found in rocks, marine and lake sediments, and fired archeological artifacts. Past and current work in this area has involved characterizing changes in the intensity of Earth’s magnetic field in marine sediments from the northeast Pacific Ocean, pot sherds from the American Southwest, pyroclastic deposits in the American west, and in modern and ancient microbialites.
(* student author)
*Jung, J.-I., and J.A. Bowles (2021), A Feasibility Study of Microbialites as Paleomagnetic Recorders, Frontiers in Earth Science, 9:603805, doi: 10.3389/feart.2021.603805. Link to pdf.
*Abdulghafur, F., and J.A. Bowles (2019), Absolute Paleointensity study of Miocene Tiva Canyon Tuff, Yucca Mountain, Nevada: Role of fine-particle grain-size variations, Geochem. Geophys. Geosys. doi:10.1029/2019GC008728. Link to pdf.
Bowles, J.A., J.S. Gee, M.J. Jackson, and M. Avery (2015), Geomagnetic paleointensity in historical pyroclastic density currents: Testing the effects of emplacement temperature and postemplacement alteration, Geochemistry, Geophysics, Geosystems, 16, doi:10.1002/2015GC005910, 3607-3625. Link to pdf.
Gee, J.S., Y. Yu, and J.A. Bowles, Paleointensity estimates from ignimbrites: an evaluation of the Bishop Tuff, Geochem. Geophys. Geosys., 11, Q03010, doi:10.1029/2009GC002834, 2010. Link to pdf.
Bowles, J., Data Report: Revised magnetostratigraphy and magnetic mineralogy of sediments from Walvis Ridge, Leg 208, In D.Kroon, J.C. Zachos, J.C., and C. Richter (Eds.), Proc. ODP, Sci. Results, 208: College Station, TX (Ocean Drilling Program), 1–24, doi:10.2973/odp.proc.sr.208.206.2006, 2006.
Bowles, J., L. Tauxe, J. Gee, D. McMillan, S. Cande, The source of tiny wiggles in Chron C5: A comparison of sedimentary relative intensity and marine magnetic anomalies, Geochem. Geophys. Geosys., 4, doi:10.1029/2002GC000489, 2003. Link to pdf.
Bowles, J., J. Gee, J. Hildebrand, L. Tauxe, Archaeomagnetic intensity results from California and Ecuador: evaluation of regional data, Earth Planet Sci. Lett., 203, 967-981, 2002.