Direct observations of degassing-induced crystallization in basalts
Direct observations of degassing-induced crystallization in basalts
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DOI：
10.1130/g33641.1
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发表时间：
2013-02-01
期刊：
影响因子：
5.8
通讯作者：
Cashman, Katharine V.
中科院分区：
文献类型：
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作者：
Applegarth, L. Jane;Tuffen, Hugh;Cashman, Katharine V.
岩浆脱气可以通过提高岩浆液温触发晶体生长。由于结晶极大地增加了岩浆的粘度，这一过程对喷发动力学有强烈的影响。我们利用显微镜和加热台首次直接观察到岩浆温度下天然玄武岩熔体中脱气驱动的晶体生长。来自意大利埃特纳火山（0.39 wt% H2O）和夏威夷基拉韦厄火山（0.18 wt% H2O）的样品在1巴的空气中加热，并在1190摄氏度到1270摄氏度之间等温保存0.5-17小时，然后冷却到固体温度。加热时，气泡在bb0 ~ 900℃时生长表明挥发性析出。在含水的埃特纳样品中，等温条件产生了许多新的斜长石晶体，这些晶体生长到
Magma degassing can trigger crystal growth by increasing the magma liquidus temperature. As crystallization greatly increases magma viscosity, this process can strongly influence eruptive dynamics. We use a microscope and heated stage to obtain the first direct observations of degassing-driven crystal growth in natural basaltic melts at magmatic temperatures. Samples from Mount Etna, Italy (0.39 wt% H2O), and Kilauea volcano, Hawaii (0.18 wt% H2O) were heated in air at 1 bar, and held isothermally for 0.5-17 h between 1190 degrees C and 1270 degrees C, before cooling to solidus temperatures. On heating, bubble growth at >900 degrees C indicated volatile exsolution. In the hydrous Etna sample, isothermal conditions produced numerous new plagioclase crystals that grew to