Physics of the Earth and Planetary Interiors 147 (2004) 285–296 Does lithology influence relative paleointensity records? a statistical analysis on South Atlantic pelagic sediments Christine Franke a,b,∗ , Daniela Hofmann a , Tilo von Dobeneck a,b a Department of Geosciences, University of Bremen, P.O. Box 330 440, D-28334 Bremen, Germany b Paleomagnetic Laboratory ‘Fort Hoofddijk’, Utrecht University, Budapestlaan 17, 3584 CD Utrecht, The Netherlands Received 24 November 2003 Abstract The relative paleointensity (RPI) method assumes that the intensity of post depositional remanent magnetization (PDRM) depends exclusively on the magnetic field strength and the concentration of the magnetic carriers. Sedimentary remanence is regarded as an equilibrium state between aligning geomagnetic and randomizing interparticle forces. Just how strong these mechanical and electrostatic forces are, depends on many petrophysical factors related to mineralogy, particle size and shape of the matrix constituents. We therefore test the hypothesis that variations in sediment lithology modulate RPI records. For 90 selected Late Quaternary sediment samples from the subtropical and subantarctic South Atlantic Ocean a combined paleomagnetic and sedimentological dataset was established. Misleading alterations of the magnetic mineral fraction were detected by a routine Fe/ test (Funk, J., von Dobeneck, T., Reitz, A., 2004. Integrated rock magnetic and geochemical quantification of redoxomorphic iron mineral diagenesis in Late Quaternary sediments from the Equatorial Atlantic. In: Wefer, G., Mulitza, S., Ratmeyer, V. (Eds.), The South Atlantic in the Late Quaternary: reconstruction of material budgets and current systems. Springer-Verlag, Berlin/Heidelberg/New York/Tokyo, pp. 239–262). Samples with any indication of suboxic magnetite dissolution were excluded from the dataset. The parameters under study include carbonate, opal and terrigenous content, grain size distribution and clay mineral composition. Their bi- and multivariate correlations with the RPI signal were statistically investigated using standard techniques and criteria. While several of the parameters did not yield significant results, clay grain size and chlorite correlate weakly and opal, illite and kaolinite correlate moderately to the NRM/ARM signal used here as a RPI measure. The most influential single sedimentological factor is the kaolinite/illite ratio with a Pearson’s coefficient of 0.51 and 99.9% significance. A three-member regression model suggests that matrix effects can make up over 50% of the observed RPI dynamics. © 2004 Elsevier B.V. All rights reserved. Keywords: Relative paleointensity; PDRM; Sediment lithology; Statistical analysis; South Atlantic ∗ Corresponding author. Tel.: +49 421 218 8922; fax: +49 421 218 8671. E-mail address: cfranke@uni-bremen.de (C. Franke). URL: http://www.geophysik.uni-bremen.de/, http://www.geo.uu.nl/∼forth (C. Franke). 1. Introduction High-resolution records of the paleointensity of the Earth’s magnetic field have been successfully ob- tained from marine (Roberts et al., 1997; Valet and 0031-9201/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.pepi.2004.07.004