Scholarlink

<p>Explosive volcanic eruptions, driven by magma fragmentation, pose significant geohazards due to their rapid energy release and widespread dispersal of pyroclasts. High magma viscosity promotes brittle fragmentation by limiting volatile escape and enhancing internal pressure buildup. Although recent studies have recognized that iron-titanium oxide nanocrystal formation increases melt viscosity, the mechanisms underlying this effect remain poorly constrained. Here we quantify the influence of nanocrystallization on magma viscosity by developing viscosity models that incorporate iron-titanium variations, calibrated against nanocrystal-free andesitic melts. Using time-resolved imaging, we show that nanocrystals form within seconds within synthetic andesitic melts. This process generates nanoscale chemical heterogeneities, including silica enrichment in the surrounding melt and aluminum-rich shells embedding the nanocrystals. These heterogeneities result in viscosity increases of up to 30-fold at eruptive temperatures. Our findings indicate that nanocrystallization modulates magma rheology during early crystallization, with direct implications for the dynamics of andesitic eruptions.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Nanoscale chemical heterogeneities control the viscosity of andesitic magmas

  • 期刊论文

  • 出版模式：

    开放获取

  • 发表日期：

    2025年6月12日

查看全文
  • Pedro Valdivia,
  • Alessio Zandonà,
  • Jessica Löschmann,
  • Dmitry Bondar,
  • Cécile Genevois,
  • Aurélien Canizarès,
  • Mathieu Allix,
  • Nobuyoshi Miyajima,
  • Alexander Kurnosov,
  • Tiziana Boffa Ballaran,
  • Fabrizio Di Fiore,
  • Alessandro Vona,
  • Claudia Romano,
  • Joachim Deubener,
  • Emily C. Bamber,
  • Alessandro Longo,
  • Danilo Di Genova

摘要

Explosive volcanic eruptions, driven by magma fragmentation, pose significant geohazards due to their rapid energy release and widespread dispersal of pyroclasts. High magma viscosity promotes brittle fragmentation by limiting volatile escape and enhancing internal pressure buildup. Although recent studies have recognized that iron-titanium oxide nanocrystal formation increases melt viscosity, the mechanisms underlying this effect remain poorly constrained. Here we quantify the influence of nanocrystallization on magma viscosity by developing viscosity models that incorporate iron-titanium variations, calibrated against nanocrystal-free andesitic melts. Using time-resolved imaging, we show that nanocrystals form within seconds within synthetic andesitic melts. This process generates nanoscale chemical heterogeneities, including silica enrichment in the surrounding melt and aluminum-rich shells embedding the nanocrystals. These heterogeneities result in viscosity increases of up to 30-fold at eruptive temperatures. Our findings indicate that nanocrystallization modulates magma rheology during early crystallization, with direct implications for the dynamics of andesitic eruptions.