Open AccessFurther reliability tests for determination of palaeointensities of the Earth's magnetic field
Author(s) -
Fucugauchi J. Urrutia
Publication year - 1980
Publication title -
geophysical journal of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0016-8009
DOI - 10.1111/j.1365-246x.1980.tb04315.x
Subject(s) - earth's magnetic field , archaeomagnetic dating , remanence , geology , demagnetizing field , geophysics , volcano , magnetic field , consistency (knowledge bases) , intensity (physics) , seismology , mineralogy , magnetization , physics , geometry , optics , mathematics , quantum mechanics
Summary. In palaeomagnetic studies of volcanic rocks it is often considered that, if the direction of NRM does not change much and the intensity de‐creases gradually and smoothly during ac cleaning, then the remanent magnetization is stable and chiefly composed of TRM. This argument is extended as a consistency check to detect unwanted effects during laboratory heating. A simple procedure which employs orientated samples and a short heating (15 min) for TRM acquisition in the laboratory has been used for determining the ancient geomagnetic field intensity using seven volcanic rocks of Late Cenozoic age from central Mexico. The main reliability tests are based on the stability of direction, the close correspondence of the entire coercitivity spectra of both NRM and TRM to ac demagnetization, the low scatter of TRM directions, close correspondence of the TRM directions and the direction of the laboratory magnetic field, proportionality of TRM intensities to applied field, susceptibility comparison before and after heating, and the within‐unit consistency of palaeointensity determinations.