Open AccessElectron Microprobe Analyses and Magnetic Properties of Non‐Stoichiometric Titanomagnetites in Basaltic Rocks
Author(s) -
Creer K. M.,
Ibbetson J. D.
Publication year - 1970
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.1970.tb01784.x
Subject(s) - basalt , electron microprobe , ilmenite , geology , geochemistry , stoichiometry , electron probe microanalysis , mineralogy , chemistry , organic chemistry
Summary Chemical analyses have been made of non‐stoichiometric (i.e. slightly oxidized) titanomagnetites in basaltic rocks from Argentina, Turkey, the Azores, the Canary Islands, Japan, Bulgaria, Aden and the Pacific area. The compositions do not differ significantly from the average compositions of titanomagnetite grains which contain ilmenite lamellae (usually taken as evidence of deuteric oxidation) in other basalts from the same regions and also from Oregon. The shapes of the thermomagnetic curves are considered to provide a rapid and useful approximation to the degree of non‐stoichiometry. This has been determined more precisely from observations that the measured Curie points are invariably higher than the compositional ones, calculated for stoichiometric titanomagnetites of the same composition. The degree of non‐stoichiometry so obtained has been represented by plotting the estimated compositions of the grains studied on a triangular plot.