Scholarlink

Abstract <p>The article focuses on the nature of olivine–plagioclase (allivalite) spherulites from a young basaltic andesite lava flow of Kudryavy volcano. The spherulites consist mainly of olivine (Fo<sub>81–77</sub>) and plagioclase (An<sub>95–92</sub>) and have a radial structure, which is not typical of allivalites of the Kuril–Kamchatka region. The study of the mineral composition and primary melt inclusions in olivine showed that they formed from a low-alumina, low-potassium melt at temperatures of 970–1075°C and oxygen fugacity corresponding to the NNO + 1.6 – NNO + 2 buffer. A characteristic feature of the initial melts was their elevated water content (4.2 wt % on average). The structural features of the spherulites suggest that the formation of dendritic zones could have occurred during decompression of the shallow chamber under Kudryavy volcano at the beginning of the eruption, with a sharp decrease in temperature by 50–70°C. The coarsely crystalline central zones of spherulites confirm the cumulative nature of their formation. The formation of central zones could have occurred during the destruction of layers and crusts of cumulates on their entry into melts heading to the surface.</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

Olivine–Anorthite Spherulites of Kudryavy Volcano: Crystallization Conditions in a Shallow Chamber

  • 期刊论文

  • 发表日期：

    2025年4月1日

查看全文
  • A. Ya. Shevko,
  • D. V. Kuzmin,
  • S. Z. Smirnov,
  • M. P. Gora,
  • I. R. Nizametdinov,
  • T. Yu. Timina

摘要

Abstract

The article focuses on the nature of olivine–plagioclase (allivalite) spherulites from a young basaltic andesite lava flow of Kudryavy volcano. The spherulites consist mainly of olivine (Fo81–77) and plagioclase (An95–92) and have a radial structure, which is not typical of allivalites of the Kuril–Kamchatka region. The study of the mineral composition and primary melt inclusions in olivine showed that they formed from a low-alumina, low-potassium melt at temperatures of 970–1075°C and oxygen fugacity corresponding to the NNO + 1.6 – NNO + 2 buffer. A characteristic feature of the initial melts was their elevated water content (4.2 wt % on average). The structural features of the spherulites suggest that the formation of dendritic zones could have occurred during decompression of the shallow chamber under Kudryavy volcano at the beginning of the eruption, with a sharp decrease in temperature by 50–70°C. The coarsely crystalline central zones of spherulites confirm the cumulative nature of their formation. The formation of central zones could have occurred during the destruction of layers and crusts of cumulates on their entry into melts heading to the surface.