Effects of superheating magnitude on olivine growth

Slow cooling during crystallisation of barred olivine chondrules

“…Such a degree of superheating is sufficient to ensure initial total melting but low enough that nucleation should not be suppressed. Indeed, nucleation is totally suppressed at degrees of superheating exceeding 400 °C (Connolly et al, 1998), although the duration of heating also effects nucleation (First et al, 2020). Therefore, our experiments confirm that the BO texture requires that chondrules were initially completely molten (Lofgren, 1989;Connolly et al, 1998;Tsuchiyama et al, 2004).…”

The effects of superheating and cooling rate on olivine growth in chondritic liquid

“…The variable degrees of superheating required to suppress nucleation in these previous studies can be explained by their different starting liquid compositions and/or experimental protocols. In particular, a recent study demonstrated that the magnitude of superheating must integrate both the degree of superheating and the time spent above the liquidus (First et al., 2020). In any case, the critical degree of superheating required to suppress nucleation can be refined for a given composition.…”

“…In superheated silicate liquids, the time spent at superliquidus temperatures can also influence the final chondrule texture (Donaldson, 1979; First et al., 2020). This parameter is important because porphyritic textures can be reproduced even after an initial superheating step if the duration of superheating is short enough to preserve nuclei or relict crystals (Connolly et al., 1998).…”

Using Chemical Affinities to Understand Disequilibrium Textures of Plagioclase Preserved in Magmatic Systems

“…In particular, previous experiments have shown that the presence of crystals prior to decompression can influence the number density of plagioclase and the morphology of plagioclase crystals, where pre-decompression crystallization could decrease the energy barrier required for nucleation during decompression (Martel, 2012). Other experiments have shown that reheating of magmas past the liquidus prior to eruption can influence texture development (First et al, 2020;Tsuchiyama, 1983 decompression reduces the amount of nucleation sites where microlites can grow (Mollo & Hammer, 2017;, and can delay nucleation with increasing initial superheating (Tsuchiyama, 1983). Thus, using chemical affinity estimates extracted via P-T-t paths from our model with crystallization and nucleation models may further help to link textures from experimental results and natural systems with thermodynamic constraints.…”