Experimental simulation of bubble nucleation and magma ascent in basaltic systems: Implications for Stromboli volcano
Experimental simulation of bubble nucleation and magma ascent in basaltic systems: Implications for Stromboli volcano
复制标题
DOI：
10.2138/am-2016-5639
复制
发表时间：
2016-09-01
影响因子：
3.1
通讯作者：
Pichavant, Michel
中科院分区：
文献类型：
--
作者：
Le Gall, Nolwenn;Pichavant, Michel
通过减压实验，模拟了含H2O-和H2O- co2的玄武岩熔体从斯特龙博利岩浆系统的深部向浅部的上升过程和溶蚀过程。一种经过充分研究的“金色”浮石是在一次中期到大规模的爆发中产生的，被用作起始材料。含挥发物玻璃的氧逸度（f(o2)）范围为NNO-1.4 ~ +0.9，温度1200℃，压力200 MPa。在快速淬火之前，将得到的无晶体和无气泡玻璃等温（1200℃）减压至最终压力P-f范围在200至25 MPa之间，线性上升速率为1.5 m/s（或39 kPa/s）。通过x射线计算机断层扫描表征的减压后玻璃的纹理是由不同的脱气机制造成的，包括气泡成核、生长、聚结、脱气以及破碎。均匀气泡成核发生在过饱和压力（饱和压力与气泡开始均匀形成的压力之差，δ P-HoN）下。
The ascent of H2O- and H2O-CO2-bearing basaltic melts from the deeper to the shallower part of the Stromboli magmatic system and their vesiculation were simulated from decompression experiments. A well-studied "golden" pumice produced during an intermediate- to a large-scale paroxysm was used as starting material. Volatile-bearing glasses were synthesized at an oxygen fugacity (f(o2)) ranging from NNO-1.4 to +0.9, 1200 degrees C and 200 MPa. The resulting crystal - and bubble-free glasses were then isothermally (1200 degrees C) decompressed to final pressures P-f ranging between 200 and 25 MPa, at a linear ascent rate of 1.5 m/s (or 39 kPa/s) prior to be rapidly quenched. Textures of post decompression glasses that were characterized by X-ray computed tomography result from different mechanisms of degassing that include bubble nucleation, growth, coalescence, and outgassing, as well as fragmentation. Homogeneous bubble nucleation occurs for supersaturation pressures (difference between saturation pressure and pressure at which bubbles start to form homogeneously, Delta P-HoN)