Paleomagnetic Recording Efficiency of Sedimentary Magnetic Mineral Inclusions: Implications for Relative Paleointensity Determinations

Abstract

Sedimentary relative paleointensity (RPI) records are often carried by complex magneticmineral mixtures, including detrital and biogenic magnetic minerals. Recent studies have demonstratedthat magnetic inclusions within larger detrital silicate particles can make significant contributions tosedimentary paleomagnetic records. However, little is known about the role such inclusions play insedimentary paleomagnetic signal recording. We analyzed paleomagnetic and mineral magnetic data formarine sediment core MD01‐2421 from the North Pacific Ocean, offshore of central Japan, to assess howmagnetic inclusions and other detrital magnetic minerals record sedimentary paleomagnetic signals.Stratigraphic intervals in which abundant magnetic inclusions dominate the magnetic signal arecompared with other intervals to assess quantitatively their contribution to sedimentary RPI signals. Thenormalized remanence record from core MD01‐2421 does not correlate clearly with global RPI stacks,which we attribute to a demonstrated lower paleomagnetic recording efficiency of magnetic inclusionscompared to other detrital magnetic minerals. We also carried out thefirst laboratory redepositionexperiments under controlled Earth‐like magneticfields for particles with magnetic inclusions usingmaterial from core MD01‐2421. Our results confirm that such particles can be aligned by ambientmagneticfields but with a lower magnetic recording efficiency compared to other detrital magneticminerals, which is consistent with normalized remanence data from core MD01‐2421. Our demonstrationof the role of sedimentary magnetic inclusions should have wide applicability for understandingsedimentary paleomagnetic recording. Show more