Gas transport and bubble collapse in rhyolitic magma: an experimental approach
Gas transport and bubble collapse in rhyolitic magma: an experimental approach
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流纹质岩浆中的气体传输和气泡破裂：一种实验方法
DOI：
10.1007/bf00302826
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发表时间：
1994
影响因子：
3.5
通讯作者：
J. Eichelberger
中科院分区：
文献类型：
--
作者：
H. Westrich;J. Eichelberger
进行了一系列实验，以检验流纹岩岩浆在上升过程中的多孔性流动脱气以及脱气岩浆中的气泡随后坍塌形成黑岩的概念。致密的、合成水合的天然玻璃在饱和水的条件下加压，然后在示踪蒸汽D2O的存在下进行减压，以获得一定范围的孔隙率。在孔隙度为60vol.%处发生了快速的同位素交换，表明蒸汽传输而不是简单的扩散，这与早先在寒冷的自然样品上测得的气体渗透率一致。在另一系列实验中，天然的和合成的浮石，通过脱气到大气压，在重新加压到熔岩流中普遍存在的适度压力时，迅速崩溃为致密的玻璃。没有残留的气泡纹理。这些结果支持这样一种假设，即喷流喷发是气体从可渗透的岩浆泡沫中协同逃逸的结果，当这种泡沫被挤出时，类似焊接的过程会产生致密的熔岩。
A series of experiments was conducted to test concepts of porous flow degassing of rhyolitic magma during ascent and of the subsequent collapse of vesicles in degassed magma to form obsidian. Dense, synthetically hydrated, natural glasses were pressurized under water-saturated conditions and then decompressed to achieve a range of porosities in the presence of a tracer vapor, D2O. Rapid isotopic exchange indicative of vapor transport rather than of simple diffusion occurred at a porosity >60 vol.%, in accord with earlier gas permeability measurements on cold natural samples. In another series of experiments, natural and synthetic pumices, vesiculated by degassing to atmospheric pressure, rapidly collapsed to dense glass on repressurization to the modest pressures prevailing in lava flows. No relict bubble textures remained. These results support the hypothesis that effusive eruptions result from the syneruptive escape of gas from permeable magmatic foam, and that a process analogous to welding yields dense lavas when such foams are extruded.