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Data report: evaluation of shipboard magnetostratigraphy by alternating field demagnetization of discrete samples, Expedition 361, Site U1475

Just, J., Hall, Ian R., Hemming, Sidney R., LeVay, Leah J., Barker, Stephen R., Berke, Melissa A., Brentegani, Luna, Caley, Thibaut, Catagena-Sierra, Alejandra, Charles, Christopher D., Coenen, Jason J., Crespin, Julien G., Franzese, Allison M., Gruetzner, Jens, Han, Xibin, Hines, Sophia K. V., Jimenez Espejo, Francisco J., Just, Janna, Koutsodendris, Andreas, Kubota, Kaoru, Lathika, Nambiyathodi, Norris, Richard D., dos Santos, Thiago Pereira, Robinson, Rebecca, Rolison, John M., Simon, Margit H., Tangunan, Deborah, van der Lubbe, Jeroen J. L., Yamane, Masako, Zhang, Hucai and Rooks-Cast, Nina 2020. Data report: evaluation of shipboard magnetostratigraphy by alternating field demagnetization of discrete samples, Expedition 361, Site U1475. Proceedings of the International Ocean Discovery Program 361 10.14379/iodp.proc.361.202.2020

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Abstract

The paleomagnetic shipboard data of International Ocean Discovery Program Site U1475, with a record reaching back to approximately 7 Ma, allowed for the identification of major magnetic polarity chrons and subchrons back to ~3.5 Ma. However, the natural remanent magnetization (NRM) was very weak, and transitional intervals with unclear polarity were as thick as several meters. The midpoints of these transitional intervals were reported in the shipboard results without decimal places because of the poor data quality. To evaluate and possibly refine the shipboard magnetostratigraphy, subsampling was performed across the polarity transitions. Detailed alternating field (AF) demagnetization experiments were conducted on these discrete samples and were complemented by anhysteretic remanent magnetization acquisition measurements and subsequent demagnetization. AF demagnetization data of NRM were analyzed using anchored principal component analysis (PCA) to obtain the characteristic remanent magnetization. These PCA results generally confirm the smoothed signal across polarity transitions at Site U1475. However, the midpoint depths of the top of the Keana Subchron, the Gauss-Matuyama and Matuyama-Brunhes boundaries, and the base of the Olduvai Subchron were adjusted.

Item Type: Article
Date Type: Published Online
Status: Published
Schools: Earth and Ocean Sciences
ISSN: 2377-3189
Funders: NERC
Date of First Compliant Deposit: 16 July 2020
Date of Acceptance: 14 April 2020
Last Modified: 31 Aug 2020 16:49
URI: http://orca.cf.ac.uk/id/eprint/133517

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