Assimilation and mixing of crystal-bearing magmas in the Snake River Plain, NW United States: rheological timescales for magmatism of large silicic provinces

美国西北部蛇河平原含晶体岩浆的同化和混合：大硅质省岩浆作用的流变时间尺度

• 批准号: 215373999
• 负责人: Professorin Dr. Cristina de Campos
• 金额: --
• 依托单位: Lehrstuhl für Mineralogie und Petrologie
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 财政年份: 2012
• 资助国家: 德国
• 起止时间: 2011-12-31 至 2014-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/215373999?language=en
• 关键词: Assimilation; mixing; crystal; bearing; magmas

The Snake River Plain (SRP) represents a unique opportunity to study the impact of a thermal anomaly on continental crust and the resulting dynamics in magma reservoirs. Deep, mantle-derived mafic melts ascend through the crust, assimilate adjacent country rock, mix and evolve. These processes, along with the composition of the primitive magma, govern the cooling and crystallisation dynamics and thus constitute a fundamental contribution to magmatic differentiation. The diversity of compositions along the SRP demonstrates the physico-chemical complexities and thus provides a keyhole to the evolution of these magmas. The textural evidence for magma mixing in core rhyolite and the stratigraphic alternation of sediments with igneous rocks in the SRP drill log indicate the occurrence of magma mixing of rhyolite (also crustally derived) and basalt melts. The continuation of a series of experiments is proposed to investigate, for the first time, the influence of crystals on magma mixing. The present proposal aims to (1) characterize the composition of recognized end-members (e.g. interstitial melt compositions, volatile and crystal content), (2) constrain the nature and timescales of mixing under contrasting crystal and/or volatile contents, and (3) compare the results to SRP units, especially those found at the interface between contrasting end-members (basalt-rhyolite; basalt-sediment), such as at the Kamama and Mountain Home drillholes.

蛇河平原（SRP）是一个独特的机会，研究热异常对大陆地壳的影响和由此产生的岩浆库的动态。深源的幔源镁铁质熔体上升穿过地壳，同化邻近的围岩，混合并演化。这些过程，沿着原始岩浆的成分，控制了冷却和结晶动力学，从而构成了岩浆分异的基本贡献。沿着SRP的成分的多样性表明了物理化学的复杂性，从而提供了一个钥匙孔，这些岩浆的演化。岩芯流纹岩中岩浆混合的纹理证据和SRP钻井记录中沉积物与火成岩的地层交替表明流纹岩（也是地壳衍生的）和玄武岩熔体的岩浆混合的发生。建议继续进行一系列实验，首次研究晶体对岩浆混合的影响。本提案旨在（1）确定公认最终成员的组成特征（例如，间隙熔体组成、挥发物和晶体含量），（2）在对比晶体和/或挥发物含量下限制混合的性质和时间尺度，和（3）将结果与SRP单元进行比较，特别是在对比端元之间的界面处发现的那些（玄武岩-流纹岩;玄武岩-沉积物），如Kamama和山居钻孔。

项目成果

Chaotic Flow Patterns from a Deep Plutonic Environment: a Case Study on Natural Magma Mixing

深成环境中的混沌流模式：自然岩浆混合案例研究

• DOI: 10.1007/s00024-014-0940-6
• 发表时间: 2015
• 期刊: Pure and Applied Geophysics
• 影响因子: 2
• 作者: De Campos C.P.

Magma mixing enhanced by bubble segregation

气泡分离增强岩浆混合

• DOI: 10.5194/se-6-1007-2015
• 发表时间: 2015
• 期刊: Solid Earth
• 影响因子: 3.4
• 作者: Wiesmaier S;Morgavi D;Renggli C;Perugini D;De Campos C.P;Hess K- U;Ertel-Ingrisch W;Lavallée Y;Dingwell D.B.
• 通讯作者: Dingwell D.B.