English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Zendy Plus

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Zendy Tools

Zendy Open

New experimental data are presented that allows the biotite-magnetite-sanidine equilibrium to be used for estimating water fugacity (f H₂O ) in hydrous phonolitic magmas. It is also demonstrated that the partly ionic model gives the best estimate for the annite activity (a annite ). Crystallization experiments were carried out on a representative sample of peralkaline, phonolitic obsidian of Montaña Blanca (MB) pumice deposit, Tenerife, Canary Islands. Experiments were performed from 720.810 °C and 50.250 MPa. Redox conditions were varied between NNO (nickel + nickel oxide) + 1 (±0.2) and FMQ (fayalite + magnetite + quartz). The majority of the experiments were done under H₂O saturation conditions (P water  = P total ). Several experiments were done using a mixed H 2 O-CO 2  fluid phase whereas in other experiments 10 or 20 wt% powdered alkali feldspar was added to the starting material. The pre-eruptive f H₂O  of the Montaña Blanca magma is estimated at 676 ± 200 bars. The pre-eruptive f H₂O  for the Fish Canyon tuff (753.2978 bars) and Bishop tuff rhyolite (1065.2440 bars) were also calculated, as well as f H₂O  for metamorphic biotite from Au Sable Forks (≈ 130 bars). The results of this study suggest that this geohygrometer can be used in any magmatic system in which biotite-magnetite-sanidine is a stable assemblage.

New experimental data on biotite + magnetite + sanidine saturated phonolitic melts and application to the estimation of magmatic water fugacity