RESET: A Method to Monitor Thermoremanent Alteration in Thellier-Series Paleointensity Experiments

Accurately estimating the paleomagnetic field intensity recorded in terrestrial and planetary materials is the key to understanding dynamo processes. Thellier-series stepwise-heating methods with partial thermoremanent magnetization (pTRM) checks for alteration are considered the most reliable technique even though pTRM checks are shown to be incapable of detecting the entirety of thermal alteration. We utilize a recently developed multidomain-correction experiment (or RESET) to monitor thermally induced magnetic property alteration that may happen to the very specimen used in Thellier-series experiments. We also use rock magnetic property changes to track the physicochemical alteration of fresh companion specimens of Galapagos lavas that were previously used for paleointensity determinations. Our results show that laboratory heating induced thermal alteration of a typical Galapagos lava sample starts to occur at around 500 degrees C. It escaped detection by pTRM checks but was caught by our RESET method. Plain Language Summary To date, there has been no way to detect the entirety of thermal alterations that may happen during laboratory heating to specimens used in Thellier-series paleointensity experiments. This study develops an experimental approach to address this issue.

Automated summary

This study developed an experimental approach to monitor the thermal alterations that may occur during laboratory heating to specimens used in Thellier-series paleointensity experiments, addressing the issue of incomplete detection of thermal alterations.