摘要
通过计算天然玻璃的氧平均体积,发现该值对于雷公墨来说基本为一常数,未显示出冲击压力的影响。火山玻璃的氧平均体积与沸石、橙玄玻璃相近,由此得出沸石、橙玄玻璃形成时体积变化趋势。氧平均体积与密度的倒数成良好直线关系,不同玻璃有不同的直线。橙玄玻璃的氧平均体积和其中水的分子体积表明水是以单个分子进入玻璃结构,类似“结晶水”和“沸石水”,而不是聚合状态的水。
The concept of volume per oxygen is introduced to reflect the packing of ions(mainly O^(2-)) in some natural glasses, including tektites, lunar glasses, tachylites, palagonites and artificial magmatic glasses as well. By the volume per oxygen is meant the volume of glass divided by the number of O^(2-) ions. The authors collect from literature the chemical compositions with corresponding densities of these glasses so as to calculate the volumes per oxygen of them. It is found that the volumes per oxygen of tektites are approximately constant. 60 tektites have an average value of 22.34(?)~3 with σ_(n-1)=0.288. This value is determined by the characteristic chemistry of tektites and can be deduced from the effects of cations in ordinary silicate glasses. According to the hypothetical impact origin. tektites are formed under the shock pressure. But the volumes per oxygen do not show any impact effect. In fact, the O^(2-) ions are most loosely packed. The reason may be that tektites undergo a process of fusion and the pressure is released.
A linear relation exists between the volume per oxygen and 1/d of tektites. The volume per oxygen and 1/d of lunar glasses, tachylites and calcalkaline artificial magmatic glasses are also linearly correlated. But the line of tektites is lower than that of other natural and artificial glasses, showing the abnormal lack of alkali metals
The volumes per oxygen of palagonites are similar to those of dry tachylites.The calculated molecular volumes of H_2O in palagonites (2 3.60(?)~3 on the average, σ_(n-1)=1.90)are within the range of crystalline water and water in zeolites(about 24.4(?)~3 on the everage, σ_(n-1)=2.1). It si thus concluded that H_2O in palagonites is similar in nature to crystalline water or water in zeolites instead of liquid water
When the volumes per oxygen of palagonites and zeolites are compared with those of volcanic glasses and liquid water, it is shown that the formation processes of palagonites and zeelites are accompanied by volume reductions so that the reactions can proceed spontaneously under the pressure of sea water or overlying sediments
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
1989年第2期9-17,共9页
Acta Petrologica Sinica
基金
国家自然科学基金
关键词
天然玻璃
氧平均体积
雷公墨
Natural glasses
Volume per exygen
Tektite
Palagonite
Molecular volume of H_2O
