Journal article
Relative Paleointensity Record of Integrated Ocean Drilling Program Site U1396 in the Caribbean Sea: Geomagnetic and Chronostratigraphic Observations in the Pliocene
GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS, v 22(7), e2021GC009677
Jul 2021
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Abstract
Continuous sedimentary records of paleomagnetic directional variability and relative paleointensity (RPI) provide valuable information on the evolution of the geodynamo while also facilitating stratigraphic correlation and age control. While the Quaternary RPI record has received much attention, Pliocene records are relatively rare. Here, a u-channel paleomagnetic study from Integrated Ocean Drilling Program (IODP) Site U1396 in the Caribbean Sea refines the shipboard-derived polarity stratigraphy and generates an RPI and directional record extending back 4.5 Ma. Rock magnetic data reveal changes in magnetic coercivity around 2.1 Ma that influences the quality of the paleomagnetic record; while the older record is well-resolved and passes RPI quality criteria, much of the younger section does not. To facilitate the development of the RPI record, spike noise associated with discrete intervals of volcanogenic sediments are filtered from the data set. The resulting record passes RPI reliability criteria between 0-0.6 Ma and 2.1-4.5 Ma and represents the highest resolution RPI record extending into the early Pliocene. We use this record to refine the existing benthic delta O-18 chronology and open the door to high-resolution RPI chronostratigraphies during the Pliocene. Although we find no evidence for a previously observed increase in magnetic field intensity after similar to 4 million years ago, we do observe an asymmetrical form to RPI in the normal polarity intervals of the Gauss chron. We also find a polarity bias in inclination that cannot be simply explained by a drill string overprint, suggesting polarity-driven field asymmetries that are particularly pronounced during the Pliocene.
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Details
- Title
- Relative Paleointensity Record of Integrated Ocean Drilling Program Site U1396 in the Caribbean Sea: Geomagnetic and Chronostratigraphic Observations in the Pliocene
- Publication Details
- GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS, v 22(7), e2021GC009677
- Publisher
- AMER GEOPHYSICAL UNION; WASHINGTON
- Grant note
- This research used samples and data provided by the International Ocean Discovery Program (IODP). Funding was provided by the NSF (OCE-1260671, OCE-1737333, and OCE-2019480) and a United States Science Support Program (USSSP) Post Expedition Award (PEA) to Hatfield. The Paleo-and Environmental Magnetic Research Laboratory at the College of Earth, Ocean, and Atmospheric Sciences, Oregon State University is supported by NSF-EAR0651585. RGH would like to thank the Captain, crew, technical staff, and shipboard scientists onboard IODP Expedition 340. In addition, RGH thanks Molly McCanta for assistance during u-channel sampling, the staff at the IODP Gulf Coast Repository, Brendan Reilly for help with optimizing the ChRM data, and Bernard Housen and Russ Burmeister at the Pacific Northwest Paleomagnetic laboratory who facilitated measurement of the hysteresis and FORC data. Detailed, thoughtful, and constructive reviews by Quentin Simon and an anonymous reviewer greatly improved this manuscript.
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Drexel University
- Web of Science ID
- WOS:000678953500018
- Scopus ID
- 2-s2.0-85111672820
- Other Identifier
- 991021860762004721
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- Collaboration types
- Domestic collaboration
- International collaboration
- Web of Science research areas
- Geochemistry & Geophysics