Open AccessExperimental evaluation of thermal recording of successive polarities during uplift of metasediments
Author(s) -
Crouzet Christian,
Rochette Pierre,
Ménard Gilles
Publication year - 2001
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1046/j.0956-540x.2001.01423.x
Subject(s) - geology , demagnetizing field , pyrrhotite , remanence , polarity (international relations) , thermal , metamorphic rock , polarity reversal , geophysics , tectonics , mineralogy , magnetization , petrology , seismology , thermodynamics , magnetic field , voltage , chemistry , pyrite , physics , cell , biochemistry , quantum mechanics
Summary The discovery of a post‐tectonic natural remanent magnetization (NRM) carried by pyrrhotite in the Dauphinoise Zone of the Western Alps allows us to test the ability of these rocks to record a sequence of magnetic polarity versus temperature acquired during their slow cooling. Several laboratory experiments [composite partial thermal remanent magnetizations (pTRMs), Thellier–Thellier experiments, TRM thermal demagnetization] as well as NRM demagnetization were performed. This shows that the pyrrhotite grains are single‐domain‐sized and that they are able to record successive independent pTRMs. The NRM thermal demagnetization analysis demonstrates the occurrence of several antiparallel components. A comparison between NRM and TRM thermal demagnetizations is attempted in order to highlight small pTRMs naturally recorded in a temperature interval of only a few degrees. We attempt to retrieve the temperature at which each reversal occurs during the post‐metamorphic cooling. This method, called thermopalaeomagnetism, is discussed and developed in order to delineate the sequence of polarity chrons recorded versus temperature.