Long-τ VRM and relative paleointensity estimates in sediments

Abstract

Geomagnetic paleointensity measurements from sedimentary records can be severely affected by viscous remanent magnetization (VRM). We present a method for determining varying amounts of long-term VRM acquired during the present polarity interval, using the typically non-linear relationship between acquisition of artificial magnetization and demagnetization of NRM. The non-linear parts are to be avoided for paleointensity determinations, but here we focus on their use for indicators of long-relaxation time VRM. The method, which does not require determining paleointensity values, suggests correlations with paleoclimate curves and age-dependent growth of VRM. Furthermore, it appears that the long-τ VRM acquired during the Pleistocene is accompanied by short-τ effects detected in the laboratory environment.