Carbon is not required during crystallization to produce ferrobasalts/ferrodiorites (FTP rocks)

摘要

Experiments were conducted to determine whether the presence of graphite is required to produce the Fe-Ti-P-enrichment, silica-depletion trend seen in ferrobasalts and ferrodiorites/jotunites. A nominally anhydrous Snake River Plain olivine tholeiite was crystallized at 9.3 kbar in Fe-Pt capsules; the composition of the Fe-Pt alloy was empirically chosen such that the charge neither lost nor gained iron. The results of these experiments and those of previous experiments conducted in graphite are strikingly similar: in both cases the residual liquids were depleted in silica and enriched in Fe, Ti, and P. We conclude that the presence of carbon is not essential for producing this distinctive trend.