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采用落珠法(falling-sphere)研究7.5、15和22.5千巴下含氟、含水钠长石熔体粘度的结果表明:在同一温度下,熔体的粘度均随压力的升高而降低。当温度为1200℃、压力从7.5千巴升至22.5千巴时,含氟熔体[钠长石+5.8重量％氟(置换熔体中的氧),以符号AbF2O_1表示]的粘度从5000±750泊降为1600±240泊。温度为1400℃时,该熔体的粘度从7.4千巴下的1300±200泊降为22.5千巴下的430±65泊。在同一温度下,钠长石+2.79重量百分比水的熔体粘度(以符号AbH_2O表示)在7.5千巴下为650±100泊,在22.5千巴下降至400±60泊。在所研究的整个压力范围内,氟(表示为F_2O_(-1))和水都使钠长石熔体的粘度大为减小。5.8重量百分比的氟[F/(F+O)摩尔=0.01]和2.79重量百分比的水[OH/(OH+O)摩尔=0.10]与熔体粘度对数效应的比率[△log η(AbF_2O_(-1))/△log η(AbH_2O)]在7.5,15和22.5千巴下分别为0.90±0.05、0.84±0.05和0.97±0.05。比较高压下钠长石熔体粘度方面已有的可靠数据可知:直至相当于下地壳的压力条件下,F_2O_(-1)和H_2O仍具有使熔体粘度减小的能力。各钠长石熔体粘度间的差异,即AbF_2O_(-1)和AbH_2O间的差异,可用AbF_2O_(-1)和AbH_2O熔体结构的相对解聚程度来解释。水的加入形成Si—OH键,从而使钠长质熔体发生解聚作用。F_2O_(-1)的置换使熔体在氟溶液的作用下形成非桥氧和畸变格架铝阳离子,从而使钠长质熔体发生解聚作用。在相当于中—下大陆地壳的压力下,钠长质熔体中水、氟使熔体粘度大为减少的效应表明在原始岩浆汇集和惰性残余组分与熔体发生分异作用过程中这两个组分对深熔熔体的动力学特性有很大的影响。
The results of falling-sphere studies on the melt viscosities of fluoride and aqueous sodium feldspar at 7.5, 15 and 22.5 kPa show that the melt viscosity decreases with increasing pressure at the same temperature. The viscosity of the fluorine-containing melt [sodium feldspar + 5.8% by weight of fluorine (oxygen in the replacement melt), indicated by the symbol AbF2O_1] at a temperature of 1200 ° C and a pressure increase from 7.5 to 22.5 kPa ranges from 5000 ± 750 poise to 1600 ± 240 poise. At 1400 ° C, the viscosity of the melt is reduced from 1300 ± 200 poise at 7.4 bar to 430 ± 65 poise at 22.5 bar. At the same temperature, the melt viscosity of albite + 2.79 weight percent water, expressed as the symbol AbH 2 O, is 650 ± 100 poise at 7.5 bar and drops to 400 ± 60 poise at 22.5 bar. Fluorine (denoted as F_2O_ (-1)) and water all reduced the viscosity of the albite melt significantly over the entire pressure range studied. The ratio of 5.8 weight percent fluorine [F / (F + O) moles = 0.01] and 2.79 weight percent water [OH / (OH + O) moles = 0.10] to the logarithm effect of melt viscosity [ (-1)) / Δ log η (AbH 2 O)] were 0.90 ± 0.05, 0.84 ± 0.05 and 0.97 ± 0.05 at 7.5, 15 and 22.5 kPa, respectively. Comparing the available data on the viscosity of sodium feldspar under high pressure, we know that F_2O_ (-1) and H_2O still have the ability to reduce the viscosity of the melt up to the pressure corresponding to the lower crust. The differences in the melt viscosities of each albite, ie, the difference between AbF 2 O 1 and AbH 2 O, can be explained by the relative degree of dissociation of AbF 2 O 1 and AbH 2 O melt structures. The addition of water forms Si-OH bonds, which depolymerize the sodium long melt. F_2O _ (- 1) replacement of the melt under the action of the fluorine solution to form a non-bridging oxygen and lattice distortion aluminum cations, so that the long melt of sodium depolymerization. Under the pressure equivalent to the crust of the middle and lower continental crusts, the effect of greatly reducing the melt viscosity of water in the long melt of sodium shows that during the initial magmatic pooling and the differentiation between the inert residual components and the melt The two components have a great influence on the kinetic properties of the melt.