Experimental temperature cycling as a powerful tool to enlarge melt pools and crystals at magma storage conditions
Experimental temperature cycling as a powerful tool to enlarge melt pools and crystals at magma storage conditions
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DOI：
10.2138/am-2016-5398
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发表时间：
2016-03-01
影响因子：
3.1
通讯作者：
Koepke, Jurgen
中科院分区：
文献类型：
--
作者：
Erdmann, Martin;Koepke, Jurgen
在接近固相线温度的高二氧化硅体系中进行实验，通常会产生太小的晶体和熔池，无法进行现场分析。在实验运行过程中摇摆温度，通过溶解较小的晶体并增加较大晶体的尺寸来加速岩浆的再结晶，从而极大地改变晶体尺寸分布。这种周期性加热和冷却的原理，例如由热岩浆反复注入引起的，也是天然岩石中斑晶结构形成的潜在加速因素。在这里，我们表明，在流体饱和的英安岩系统中，温度循环具有显著扩大熔池和晶体的潜力。以从太平洋-南极海隆挖出的一块天然英安岩为原料，在200 Mpa下，系统地进行了两种不同温度和不同水活度的温度循环结晶实验。对于950摄氏度的实验(其中(H2O)类似于1，类似于0.3，以及
Experiments in high silica systems at temperatures close to the solidus often produce crystals and melt pools that are too small for in situ analysis. Oscillating the temperature during an experimental run speeds up recrystallization of magma by dissolving small and increasing the size of larger crystals, dramatically changing the crystal size distribution. This principle of periodic heating and cooling, caused for example by repeated injection of hot magma, is also a potential acceleration for the formation of phenocrystic textures in natural rocks.Here we show that temperature cycling has the potential to significantly enlarge melt pools and crystals in a fluid saturated dacitic system. Using a natural dacite dredged from the Pacific-Antarctic Rise as starting material, we performed crystallization experiments applying temperature cycling systematically for two different temperatures and different water activities at 200 MPa. For experiments at 950 degrees C (with a(H2O) similar to 1, similar to 0.3, and