BIOGEOCHEMICAL REMANENT MAGNETIZATION IN PELAGIC SEDIMENTS OF THE WESTERN EQUATORIAL PACIFIC-OCEAN

Paleomagnetic data from pelagic sediments are an important source of i nformation on the history of the geomagnetic field. However, fundament al uncertainties about how these sediments acquire their magnetization s remain. Here we address whether biogenic magnetite, formed at depth within the sediments, can contribute to remanent magnetizations. In se diments of the western equatorial Pacific Ocean (ODP Site 805), biogen ic magnetite found near the Fe-redox boundary carries a natural remane nt magnetization. Because the production of biogenic magnetite is tied to the geochemical zonation of the sediments, we call this magnetizat ion a biogeochemical remanence. These data indicate that some pelagic sediments can continue to acquire remanence significantly after the po st-depositional lock-in of detrital magnetic grains.