Petrogenetic implications of chromite-seeded boninite crystallization experiments: Providing a basis for chromite-melt diffusion chronometry in an oxybarometric context

Abstract

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A comparison of trace element concentrations in chromite from komatiites, picrites, and layered intrusions: implications for the formation of massive chromite layers

“…The marginal sills of the Bushveld Complex contain <1% chromite, and these chromites have similar compositions to the chromite from the Alexo komatiites in terms of 3+, 4+, and 5+ elements. The tendency of the 3+, 4+, and 5+ ions in the volcanic and sill rocks to maintain their initial concentrations may be because the chromite and liquid cooled relatively quickly and there was insufficient time for these elements to diffuse due to their slower diffusion rates (Coulthard et al 2021) The effects of re-equilibration on the chromite from within the intrusions require serious consideration. The chromite could have been in contact first with a fractionating liquid and subsequently with interstitial silicate minerals at high temperatures for a lengthy period.…”

The kinetic effect induced by variable cooling rate on the crystal-chemistry of spinel in basaltic systems revealed by EPMA mapping

“…Many studies demonstrate that the crystal-chemistry of spinel-structured oxides (hereafter referred as spinels) is able to reconstruct crystallization conditions, such as equilibrium (or dis-equilibrium) growth, T, P and fO2 of solidification (Ghiorso and Sack 1991;Toplis and Carroll 1995;Scaillet and Evans 1999;Mollo et al, 2013;Coulthard et al, 2021;Keller et al, 2023). Experiments have also highlighted that the crystal-chemistry of magmatic spinel depends on the chemical solidifying system and crystallization of other silicate phases (Hammer, 2006;Iezzi et al, 2008Iezzi et al, , 2011Mollo et al, 2013;Mollo and Hammer, 2017;Giuliani et al, 2022).…”