Multi-protocol palaeointensity determination from middle Brunhes Chron volcanics, Datong Volcanic Province, China

A full vector palaeomagnetic analysis of basalts from the Datong Volcanic Province, China, has been carried out to constrain the orientation and magnitude of the geomagnetic field during the mid-Brunhes Chron at approximately 0.41 Ma. Palaeomagnetic directions were determined using thermal demagnetization. Palaeointensity information was determined using a multi-protocol approach: (1) a Thellier-type protocol, (2) the multi-specimen parallel differential partial thermoremanence method, and (3) the Wilson method. The most consistent data set was obtained with the Wilson method, whilst similar average values, with wider data scatter, were obtained with the Thellier method. Higher values were obtained with the multi-specimen method. We suggest that consistency of results from the different protocols, which access different sections of the blocking/unblocking spectra, provide a useful test of the robustness of palaeointensity estimates. A mean virtual dipole moment of 5.4 ± 0.6 × 1022 Am2 was determined, which agrees well with coeval values from the PINT database and with the higher average palaeointensities for the mid-Brunhes Chron indicated by more continuous sedimentary relative palaeointensity records.

► Multi-protocol palaeointensity study of mid-Brunhes Chinese volcanics (Datong).
► Consistent results from two protocols.
► No evidence for low-geomagnetic dipole field intensity.