# Magnetic parameters derived from a sediment core from the western equatorial Pacific over the last 100 ka: sedimentary inputs and climatic variations.

Louise Dauchy-Tric, Franck Bassinot, Julie Carlut

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Louise Dauchy-Tric, Franck Bassinot, Julie Carlut. Magnetic parameters derived from a sediment core from the western equatorial Pacific over the last 100 ka: sedimentary inputs and climatic variations. EGU General Assembly 2025, European Geosciences Union, May 2025, Vienne, Austria. 10.5194/egusphere-egu25-17422. http://hal-05369454

HAL Id: hal-05369454

https://hal.science/hal-05369454v1

Submitted on 17 Nov 2025

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# Magnetic parameters derived from a sediment core from the western equatorial Pacific over the last ~ 100 ka: sedimentary inputs and climatic variations.

Louise Dauchy-Tric<fnref n="1" />, Franck Bassinot<fnref n="2" />, and Julie Carlut<fnref n="1" />

The magnetic parameter variations of core MD01-2385 revealed a climatic signal recorded over the last 100 ka. This core was retrieved on the northwest margin of Papua-New Guinea, in the western equatorial Pacific Ocean. This area is located in the Western Pacific Warm Pool (WPWP), which is a major source of heat and moisture to the atmosphere and plays an important role on global climate. The climate of this region is complex, being affected by the El Nino-Southern Oscillation (ENSO) and the Australian-Indonesian monsoon.

Core MD01-2385 was dated by correlating the planktonic oxygen isotope record with a global stack for the 100-40 ka interval and using ¹⁴C for the last 40 ka. The mean sedimentation rate is ~20 cm/ka over the last 100 ka. A sample was taken every 2 cm, which corresponds to a time resolution of about 100 years. The saturation magnetization (Ms) is interpreted as tracing the proportion of magnetite in the detrital fraction. At orbital time scale, Ms variations correlate with the New Guinea physical erosion proxy estimated by Yu et al. (2023) on the same core, reflecting past variations in precipitation intensity in the region. During the Holocene, long scale Ms variations correlate quite well with september local insolation variations controlled by precession, which suggest a sensitivity to ENSO oscillation regime. However, during the last glacial period, the correlation between long scale M~s~ variability and precession dominated insolation is less obvious. The difficulty seems to be due to the high amplitude of centennial to millennial variability superimposed on the long-period signal, distorting the precessional component. A first estimation of the suborbital variability suggests a periodicity of ~4 ka. An interval of low concentration in magnetite is synchronous with the Heinrich 1 event, which we interpret as resulting from a decrease in precipitation, in good agreement with the New Guinea physical erosion proxy from Yu et al. (2023).

<footnote n="1">¹Universite Paris Cite, Institut de Physique du Globe de Paris, CNRS UMR-7154, Paris Cedex 05, France (dauchy@ipgp.fr)</footnote>

<footnote n="2">²LSCE/IPSL, CEA-CNRS-UVSQ, Universite Paris-Saclay, Gif-sur Yvette, France</footnote>