Geomagnetic Field Paleointensity Spanning the Past 11 Myr From Marine Magnetic Anomalies in the Southern Hemisphere

Abstract

The geomagnetic field is derived from convection of its liquid outer core (Merrill & McFadden, 1995). The recognition of global geomagnetic field behavior, such as polarity reversals, allowed scientists to build Geomagnetic Polarity Time Scales (GPTS) with the most recent version published in 2020 (GPTS2020; Ogg, 2020). And global variations in geomagnetic field intensity can also provide additional dating markers (Singer, 2014). These are especially helpful when continuous paleointensity records can be correlated with sedimentary δ 18 O records, as this can establish a more robust chronology for climate change events (Richards & Andersen, 2013;Stoner et al., 2000).Sedimentary sequences can record continuous changes in relative paleointensity (RPI). However, recovering a long-time interval usually equates to a thick sedimentary column (e.g., 10 Myr corresponding to 200 m or more), which can be difficult (Valet et al., 2020). In fact, there are very few continuous sedimentary records that span the last 11 Myr. Yamazaki and Yamamoto (2018) reconstructed RPI records over the last 8 Myr from eastern equatorial Pacific Ocean sediments, which is the longest continuous sedimentary paleointensity record recovered to date. In addition, environmentally (biogenic or terrigenous) induced

Significance of Short‐Wavelength Magnetic Anomaly Low Along the East Pacific Rise Axis, 9°50′N

“…Shorter wavelength anomaly variations may arise from a variety of causes. Within some longer polarity intervals, sea surface anomaly profiles reveal shorter wavelength variations that appear to be consistent regionally or globally, and therefore have been interpreted as likely reflecting geomagnetic intensity variations (e.g., Cande & Kent, 1992; Gee et al., 1996; Li et al., 2021). Magnetic anomaly amplitudes may also be modulated by a variety of crustal accretionary processes.…”