Publications

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2019
Korte, M, Brown MC, Gunnarson SR, Nilsson A, Panovska S, Wardinski I, Constable CG.  2019.  Refining Holocene geochronologies using palaeomagnetic records. Quaternary Geochronology. 50:47-74.   10.1016/j.quageo.2018.11.004   AbstractWebsite

The aperiodic nature of geomagnetic field variations, both in intensity and direction, can aid in dating archaeological artefacts, volcanic rocks, and sediment records that carry a palaeomagnetic signal. The success of palaeomagnetic dating relies upon our knowledge of past field variations at specific locations. Regional archaeo- and palaeomagnetic reference curves and predictions from global geomagnetic field models provide our best description of field variations through the Holocene. State-of-the-art palaeomagnetic laboratory practices and accurate independent age controls are prerequisites for deriving reliable reference curves and models from archaeological, volcanic, and sedimentary palaeomagnetic data. In this review paper we give an overview of these prerequisites and the available reference curves and models, discuss techniques for palaeomagnetic dating, and outline its limitations. In particular, palaeomagnetic dating on its own cannot give unique results, but rather serves to refine or confirm ages obtained by other methods. Owing to the non-uniform character of magnetic field variations in different regions, care is required when choosing a palaeomagnetic dating curve, so that the distance between the dating curve and the record to be dated is not too large. Accurate reporting and incorporation of new, independently dated archaeo- and palaeomagnetic results into databases will help to improve reference curves and global models for all regions on Earth.

2006
McMillan, DG, Constable CG.  2006.  Limitations in correlation of regional relative geomagnetic paleointensity. Geochemistry Geophysics Geosystems. 7   10.1029/2006gc001350   AbstractWebsite

Time domain correlations of common features among relative paleointensity records from sedimentary cores are invaluable to paleomagnetism and paleoclimatology. Sediments with high accumulation rates might now provide millennial scale correlations of temporal variations in the geomagnetic dipole moment. Errors in the ages of paleomagnetic data samples, however, can make such correlations difficult and unreliable. We use spectral methods to assess the level of coherence expected among individual and stacked high- resolution simulated paleointensity records for the time interval 0 - 75 ka. Correlations between individual paleointensity records are systematically degraded with decreased sedimentation rate and increased magnitude of age errors. We find that with optimistic age errors and interpolation of depth sampled data to evenly spaced time series, only short period signal in high- resolution relative paleointensity is corrupted. For currently available methods of establishing chronologies, we estimate the minimum characteristic timescale of correlative features between pairs of regional stacked records at about 4.5 kyr. From an analysis of NAPIS- 75 and SAPIS data, it appears that the limit is inherent to the regional stacks and not a consequence of comparison of distant, independent data sets. A detailed comparison of the NAPIS- 75 and SAPIS stacks shows that this limit is likely larger, perhaps 6 kyr. At long periods the two regional stacks are more poorly correlated than those from our simulations, suggesting somewhat larger age errors in the individual paleointensity records.