Ž . Earth and Planetary Science Letters 143 1996 269–274 Express Letter Towards absolute calibration of sedimentary paleointensity records Catherine Constable a, ) , Lisa Tauxe a,b a Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, La Jolla, CA 92093-0225, USA b Fort Hoofddijk Paleomagnetic Laboratory, Budapestlaan 17, 3584 CD Utrecht, The Netherlands Received 17 May 1996; accepted 27 June 1996 Abstract Using relative paleointensity estimates derived from twelve globally distributed pelagic sediment cores, we assess whether they record a signal consistent with that expected from a dominant geocentric axial dipole. The cores span the Matuyama–Brunhes boundary and we normalize the observations by supposing that at the time the direction reverses the intensity low reflects only the non-axial-dipole contribution to the field. We further assume that this non-axial-dipole contribution to the field is invariant with geographic location. From absolute paleointensity compilations we estimate its size to be about 7.5 mT; this supplies the calibration for the axial dipole signal away from the extreme low in intensity. The data predict the dipole field variation with latitude with similar accuracy to that observed in absolute paleointensity records, and show similar behavior when transformed to virtual axial dipole moments. Keywords: paleomagnetism; natural remanent magnetization; magnetic intensity; sediments; calibration 1. Introduction Reliable estimates of the paleointensity of the geomagnetic field are notoriously difficult to acquire. Absolute measures of paleointensity require that the remanence be thermomagnetic in origin, and that its acquisition can be simulated in the laboratory with- out alteration of the magnetic mineralogy during heating. This forms the basis of the well known wx Thellier method 1 . In practice, the Thellier method often does not produce results that satisfy internal Ž wx. consistency checks against alteration e.g., 2.A ) Corresponding author. E-mail: cconstable@ucsd.edu recent compilation of all published absolute paleoin- tensity data spanning ages greater than 30 kyr con- wx tains 1123 flow mean data 3 . An alternative means of acquiring information about paleointensity is to use sedimentary sequences and examine temporal fluctuations in the appropriately normalized natural remanent magnetization. The methodology has re- wx cently been reviewed 4 . Because the process of remanence acquisition cannot be simulated accu- rately in the laboratory, there is no method analogous to that of Thellier for absolute calibration of sedi- ment paleointensity data. Nonetheless, reliable sedi- mentary records offer several advantages over typi- cal Thellier results. Sampling is not limited by the sporadic temporal and spatial occurrence of volcanic eruptions, and it is possible to obtain more or less 0012-821Xr96r$12.00 Copyright q 1996 Elsevier Science B.V. All rights reserved. Ž . PII S0012-821X 96 00128-8