A test of the pseudo-Thellier technique for determining relative palaeointensity in the Tirna Basin, Osmanabad, Maharashtra, India

Abstract

AbstractA relative palaeointensity determination was obtained using the pseudo-Thellier technique on sediment from Ther, Tirna Basin, Latu-Osmanabad District, Maharashtra, India. The stability of the natural remanent magnetization was investigated by alternating field (AF) demagnetization. Rock magnetic studies suggest that the main carriers of magnetization are ferrimagnetic minerals, predominantly pseudo-single-domain magnetite. To varying degrees, the smoothed palaeoinclination and palaeodeclination patterns of the Tirna Basin are similar to other Asian palaeosecular variation records CALS3k.4, CALS10k.1 and SED3k.1, with an age offset. Measurements of intensity of the natural remanent magnetization left after AF demagnetization v. intensity of anhysteric remanent magnetization gained at the same peak were carried out on a set of samples. A jackknife re-sampling scheme provides error estimates for the palaeointensity. A good agreement pattern can be observed between the Tirna Basin relative palaeointensity proxy and other global curves with an age shift. Although some temporal offsets of palaeointensity features between different records have been recognized, their similar shape suggests that the palaeointensity can give a globally coherent signal and may be used as a relative dating technique. For the first time, relative palaeointensity data for the past 2 kyr from India is presented here, which complement the existing archaeological records but with an additional input.