Effects of variable sedimentation rates and age errors on the resolution of sedimentary paleointensity records

Abstract

[1] Synthetic, u-channel records of relative paleointensity have been generated with a numerical model simulating the recording process in sediments, variable quality age control and variable sedimentation rates, over a time interval of 500 ky. Simulation results indicate that paleointensity records with mean sedimentation rates up to 15 cm/ky can reflect geomagnetic dipole intensity fluctuations, with some amplitude differences between individual records of nongeomagnetic origin. This study confirms that relative paleointensity records have great potential as a stratigraphic tool and that a stratigraphic precision of a few thousand years can be achieved with records characterized by high sedimentation rates. Spectral analyses suggest that caution should be used when interpreting the power spectra of individual records and that stacked records should be favored. Stacked u-channel records with mean sedimentation rates of 1 cm/ky do not provide reliable spectral information on the dipole intensity for wavelengths shorter than 25–50 ky, and their utility is limited to long-term trends in paleointensity. For higher sedimentation rates, the range of spectral information depends on the stack resolution (sedimentation rates) and the age model. The best results are, predictably, obtained with high sedimentation rates and excellent age control. In these cases, the power spectra are reliable for wavelengths as short as 4 ky.