A LabVIEW software for Thellier paleointensity measurements with an automated three-component spinner magnetometer TSpin

Abstract

The Thellier method is classical but is still regarded as the most reliable method for paleointensity determination. Recently, many types of additional protocols have been advocated to ensure reliability and make laboratory work more laborious and time-consuming. An automated system coupling a magnetometer and an electric furnace is now of prime importance to cope with the increasing demand. Here, we describe a graphics-based program for controlling a fully automatic system combining a spinner magnetometer and a thermal demagnetizer, and for acquiring and processing the magnetization data. A single fluxgate sensor, which can measure the vector magnetization by spinning and translating a standard-sized 1-in. specimen, was calibrated with a rotatable reference specimen that can make the magnetization parallel or perpendicular to the spinning axis. By placing a cooling chamber between the furnace and the sensor for the updated system, the specimen can be heated up more efficiently to ensure an identical thermal history for the double heatings of the Thellier method. The direction of the vector magnetization was precisely obtained as well as the intensity, the results being comparable with those from an ordinary spinner magnetometer. We present an application of the fully automatic system for a Thellier measurement on a recent lava flow, which took about 24 h for approximately ten-step double heatings without manual operation.

Special issue on “Recent advances in environmental magnetism and paleomagnetism”

“…A technical report by Fukuma and Kono (2016) presented a LabVIEW software program to control an automated three-component spinner magnetometer equipped with a thermal demagnetizer TSpin, which is utilized for routine operations in Thellier paleointensity experiments, enabling an overnight Thellier measurement without any user intervention. Due to a continuous series of remanence measurements combined with thermal demagnetization or partial thermoremanent magnetization (TRM) acquisition in a magnetic shield case without manual handling of a specimen, the chance of an orientation error or acquisition of spurious magnetization is almost completely eliminated.…”