Kiglapait Mineralogy II: Fe-Ti Oxide Minerals and the Activities of Oxygen and Silica

1 November 1980

journal article
Published by Oxford University Press (OUP) in Journal of Petrology

Vol. 21 (4) , 685-719
https://doi.org/10.1093/petrology/21.4.685

Abstract

Cumulus titanomagnetite and subordinate ilmenite first appear in the Upper Zone of the Kiglapait intrusion. They arrive gradually and then reach abnormal abundances before falling to a sustained cotectic mode near seven volume per-cent. The most Ti-rich titanomagnetites (to Usp ₆₆) are preserved in ore bands (layers) which solidified by adcumulus growth leading to the complete expulsion of interstitial silicate liquid. Analyses from three of these ore bands, applied to the solution model of Lindsley (1977), form a single linear array in f_{o₂ versus 1/T °K, with log f_{o₂ = (−28,283 ± 89)/T + 11.03 ± 0.25. This array implies log f_{o₂ = −9.65 at 1094 °C, the model temperature of the Main Ore Band, consistent with primary mineral compositions Ilm₈₉, Usp₇₉ and a weight mode of 18 per cent ilmenite.}}}

Keywords

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