Open AccessImportance of cooling rate dependence of thermoremanence in paleointensity determination
Author(s) -
Yu Yongjae
Publication year - 2011
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2011jb008388
Subject(s) - magnetite , remanence , demagnetizing field , magnetization , curie temperature , intensity (physics) , natural remanent magnetization , geology , condensed matter physics , thermal , materials science , mineralogy , thermodynamics , ferromagnetism , physics , optics , magnetic field , quantum mechanics , paleontology
The practical effect of cooling rate on the magnitude of thermal remanent magnetization (TRM) is experimentally tested, using both natural and synthetic magnetites. For synthetic and natural single‐domain (SD) magnetites, TRM intensity increases as the cooling rate decreases because a longer exposure time for slower cooling offers more chances to achieve an equilibrium magnetization. Multidomain (MD) magnetites have the opposite response: TRM decreases as the cooling rate increases because slower cooling allows more time to achieve lower magnetization because of self‐demagnetization. For pseudo‐single‐domain (PSD) magnetite, the effect of cooling rate on the remanence intensity appears to be insignificant, intermediate in behavior between SD and MD. For a SD, TRM differences are restricted to lower temperatures but diminish near the Curie point, strongly indicating a serious problem in a conventional treatment of cooling rate correction. On the practical side, merely applying TRM differences as a correction can overcorrect the true paleointensity. Another important significance of the present study is that a cooling rate difference alone can cause a slight nonlinearity in an Arai plot for a SD.