镜泊湖地区全新世火山岩熔体结构及其与某些岩浆动力学过程关系探讨

Melt structure of Jingpohu Holocene volcanic rocks and its relation to some magmatic dynamics

熔体结构对岩浆的物理和热力学性质起着重要的制约作用。本文以镜泊湖全新世火山为例 ,讨论了熔体结构和某些火山喷发机制的关系。熔体结构的NBO/T值 (每个四次配位阳离子所含有的非桥氧数 )是基于岩浆的主要元素和挥发分含量的计算获得的。研究结果表明 ,NBO/T值越高的岩浆 ,喷发时溢流出的熔岩比例越高 ,熔岩流流动的距离越长 ,越有利于熔岩隧道的形成 ,H2 O+

Melt structure plays an important role in governing physical and thermodynamic characteristics of magmas. Exemplified by Jingpohu Holocene volcanic rocks, this paper has discussed the relationship between melt structure and volcanic eruptive mechanism. The NBO/T values (the non-bridge oxygen numbers per unit of cations) are calculated on the basis of the concentrations of major elements and volatiles. The results show that the proportion of lava in the total eruptive volume and its flowing capacity increase with increasing NBO/T values. The lava with high NBO/T values is liable to generate the lava channel. Volatiles such as H_2O and F are likely to concentrate in magma with high NBO/T values.