A detailed paleomagnetic record between 2.1 and 2.75 Ma at IODP Site U1314 in the North Atlantic; geomagnetic excursions and the Gauss-Matuyama transition

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doi: 10.1029/2012GC004080
Author(s): Ohno, Masao; Hayashi, Tatsuya; Komatsu, Fumiki; Murakami, Fumi; Zhao, Meng; Guyodo, Yohan; Acton, Gary; Evans, Helen F.; Kanamatsu, Toshiya
Author Affiliation(s): Primary:
Kyushu University, Department of Environmental Changes, Fukuoka, Japan
National Museum of Nature and Science, Japan
Institut de Mineralogie et de Physique des Milieux Condenses, Japan
University of California at Davis, United States
Lamont-Doherty Earth Observatory, United States
Japan Agency for Marine-Earth Science and Technology, Japan
Volume Title: Geochemistry, Geophysics, Geosystems - G<sup>3</sup>
Source: Geochemistry, Geophysics, Geosystems - G>3`, 13(5). Publisher: American Geophysical Union and The Geochemical Society, United States. ISSN: 1525-2027
Note: In English. Includes appendices. 59 refs.; illus., incl. 1 table
Summary: This study investigated the detailed geomagnetic field variation between 2.1 and 2.75 Ma from a sediment core (IODP Site U1314) with high sedimentation rate (≥10 cm/kyr) and good age control. Characteristic remanent magnetization directions were well resolved by stepwise alternating field demagnetization. As a proxy of relative paleointensity, natural remanent magnetization (NRM) normalized by anhysteretic remanent magnetization (ARM) was used after testing that the influence of magnetic interaction in ARM is negligible. As a result, the following features of the geomagnetic field in the studied period have been revealed. During the transition of the Gauss-Matuyama (G-M) reversal and the Reunion Subchron, the paleointensity decreased to the value lower than 20% of the average intensity in the whole studied interval. In addition to these lows, eight paleointensity lows were found associated with large directional changes that satisfy the definition of a geomagnetic excursion. Four of these have ages close to ages reported for geomagnetic excursions in prior studies, whereas the other four excursions have not previously been observed. In our results, we confirm that the G-M transition occurred in marine isotope stage 103 even if we consider the shift in depth due to the lock-in process of magnetic particles. The temporal variation in paleointensity showed asymmetric behavior associated with the G-M transition, with a gradual decrease prior to the transition and a rapid recovery after the transition.
Year of Publication: 2012
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; 18 Geophysics, Solid-Earth; Atlantic Ocean; Cenozoic; Demagnetization; Expedition 306; Expeditions 303/306; Gauss Chron; IODP Site U1314; Indian Ocean Islands; Integrated Ocean Drilling Program; Magnetic excursions; Magnetic intensity; Magnetization; Mascarene Islands; Matuyama Chron; Natural remanent magnetization; Neogene; North Atlantic; Northeast Atlantic; Paleomagnetism; Pleistocene; Pliocene; Polar wandering; Quaternary; Remanent magnetization; Reunion Subchron; Reversals; Tertiary; Upper Cenozoic
Coordinates: N562200 N562200 W0275300 W0275300
Record ID: 2013072424
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