EarthRef.org Reference Database (ERR) -- Tanaka et al. 1994

Eight volcanic rocks from Japan and New Zealand in the age range 10-50 ka B.P. were studied using the Thellier method paleointensity experiment and yielded five successful results for 10-22 ka. Samples from the Shikotsu, Kuttara and Daisen volcanoes in Japan were taken from pyroclastic flows (both welded and non-welded) and a pumice fall deposit. One of the two New Zealand rocks is a rhyolite lava from the Taupo Volcanic Zone. Four sites out of seven located on rocks that are not usually subjected to Thellier's experiment yielded successful results, which indicates that volcanic products such as pyroclastic flows and rhyolite lavas are as good a material as basalt and andesite lavas for application of the paleointensity experiment. One paleointensity from New Zealand at 9.9 ka is very large, at about 100 muT, and provides support for the paleointensity high found in Europe and Japan [1,2]. The other four paleointensities for 14-22 ka are smaller than the present-day value, and this agrees with the idea of a broad paleointensity minimum for the period 10-50 ka that was suggested by McElhinny and Senanayake [3]. It is also noted that the variation curve of absolute paleointensity from the volcanic rocks is reasonably similar to the relative paleointensity curves from marine and lake sediments which were summarized by Tauxe [4].