iiinova — where your digital self keeps evolving

Replies

Nick Barber 🌋 @volcannick.bsky.social · 16/04/2026

🌋 peeps - pretty cool open access study of melt inclusion "speedometry" applied to Mount Saint Helens 1980. Simple approach, but potentially useful as so many melt inclusions exhibit the kind of crystallized structure Don is investigating. pubs.geoscienceworld.org/msa/ammin/ar...

pubs.geoscienceworld.org

Using delayed nucleation in melt inclusions to constrain final growth durations of magmatic crystals: An introduction and example using the May 18, 1980, White Pumice of Mt. St. Helens | American Mine...

153 0

Nick Barber 🌋 @volcannick.bsky.social · 16/04/2026

Crux of the findings: melt inclusion degree of crystallinity fit to classical nucleation theory and then time intervals of crystal growth. Conclusion is that melt inclusions start growing daughter crystals around the same time earthquakes and gas emissions kick off before May 18 1980 MSH eruption!

Histogram of melt inclusion abundance vs. melt inclusion volume separated into inclusions that are all glass (337 inclusions) and those that contain some crystals (65 inclusions). The largest inclusions contain crystals, whereas the smallest are dominated by crystal-free glass, as observed by Roedder (1976) in the rocks that he studied.

Plot of duration, Δt, vs. the time-average nucleation rate, ⟨J⟩. The value of ⟨J⟩Δt calculated from the melt inclusions is plotted as the solid blue diagonal line. The uncertainties (dashed blue lines) are estimated from the minimum and maximum values of ⟨J⟩Δt calculated from the melt inclusion fits, as discussed in the text. These uncertainties are equal to, or a little greater than, the 95% confidence bounds calculated by the Matlab “fit” function calculation of ⟨J⟩Δt. Note that durations <0.1 day (2.4 h) and nucleation rates>1010 nuclei m−3 s−1 are not plotted in the figure. The range in measured nucleation rates from the studies cited in Figure 7 is plotted as bars across the top of the figure, and the intersection of the minimum nucleation rates in each study (vertical dashed lines) with the value of ⟨J⟩Δt provides a maximum estimate of Δt. The gray transition region between tabular and hopper plagioclase habits (see Fig. 7) is thought to be the best method for the estimation of ⟨J⟩ for the melt inclusions. The intersection of its boundaries with the ⟨J⟩Δt line yields the best estimates of Δt, from ∼4 to 100 days. Please see the text for further details.

173 0

Nick Barber 🌋 @volcannick.bsky.social · 16/04/2026

Would be curious to see how a more careful volumetric profile than an assumed best-of-fit ellipse - perhaps mapped in a real 3D volume using Raman spectroscopy - would enhance or degrade these findings...

010 0