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Infrared spectroscopy experiments do not indicate a significant relaxation of water-bearing species along the NaAlSi3O8-KAlSi3O8 join below the glass transition temperature. The temperature causes a minor influence on the melt speciation at the glass transition. Usage of determined absorptivities for H2O and OH for each melt composition quantifies the speciation of water in the quenched glasses. The speciation of water variates with temperature and is insensitive to the K-Na exchange.

Addition of alkali oxides to a haplograntic melt radically reduces the viscosity of the melt. Researchers added incremental amounts of lithium, sodium, potassium, rubidium and cesium oxides to melt solutions and measured the resulting change in viscosity. The first small additions of oxides reduced the viscosity extremely, with somewhat less dramatic affect upon further additions. Overall viscosity was higher the larger the cation size, so cesium oxide created the least amount of viscosity reduction and lithium the most.

The effect of phosphorus on density, viscosity and redox ratio of ferric-basalts melt is determined experimentally. The density of the ferro-basaltic melt decreases with the addition of phosphorus. The viscosity increases when there is a large addition of phosphorous while small addition of phosphorus does not produce significant changes in the viscosity. The redox property indicates that the presence of phosphorus in ferric iron yields large quantities of ferro-basaltic melt.

A combination of scanning calorimetry and dilatometry analysis was used to study silicate expansivity-temperature relationships and to derive a density model for granite and pegmatite petrogenesis based from the characteristics of the haplogranitic melt. The addition of 4.55 wt% fluorine reduces the density of haplogranitic melts at 750 degrees C from 2.295 g/cm3 to 2.261 g/cm3. This, in turn, accelerates the gravity-driven crystal-melt fractionation processes.

Research describing the temperature-dependent thermal expansitivities of glasses and liquids in the ternary albite-anorthite-diopside is presented. Calorimetry, dilatometry, and Pt and Ir double bob Archimedean densitometry were applied to measure the given liquid's properties. Temperature-dependent thermal expansitivities or non-linear temperature dependence of molar volume were observed as glass transition and superliquids temperatures of liquid volumes were approached.

A study was conducted on the influence of B2O3 on the viscosity of haplogranatic liquids. A nonlinear decrease of viscosity was observed in haplogranite liquids with the introduction of B2O3. The liquids were subjected to a temperature interval of 600 to 1,600 degrees Celsius. The temperature dependence of the viscosity of the liquids tested was found to be Arrhenian. The results show that boron must be treated as a fluxing agent in boron-rich and pegmatitic systems.

A study was conducted on the fluxing effect of fluorine on the glass transition behavior of silicate melts using scanning calorimetry. Results show that the presence of flourine in silicate melts promotes a strong, nonlinear decrease of the glass transition temperature. Peak temperatures provided viscosity data that showed the temperature dependence of viscosity in the melts. Fluorine and water were also found to have similar effects on the glass transition temperature.

The viscosities of a series of granitic (sensu lato) melts have been determined in the range of [10.sup.3] to [10.sup.12] Pa [multiplied by] s. The anhydrous melt compositions are based on the addition of 10, 20, 50, and 75 wt% of the anorthite component (Ca[Al.sub.2][Si.sub.2][O.sub.8]) to a haplogranitic melt (HPG8) whose composition lies near the 2 kbar water-saturated minimum melt composition in the system NaAl[Si.sub.3][O.sub.8]-KAl[Si.sub.3] [O.sub.8]-Si[O.sub.2]. Melts with 10 and 20 wt% normative anorthite were subjected to high-pressure hydration syntheses using a piston-cylinder apparatus to generate water contents up to 2 wt%. Viscosities were determined for the anhydrous melts using the concentric cylinder method in the viscosity range of [10.sup.2] to [10.sup.5] Pa [multiplied by] s, and for both anhydrous and hydrated melts in the range of [10.sup.9] to [10.sup.12] Pa [multiplied by] s. The results for the temperature dependence of viscosity in the anhydrous system indicate that the influence on melt viscosity, caused by the addition of normative anorthite to the haplogranitic melt composition, is strongly temperature-dependent. Viscosity-temperature relationships of the melts become much more non-Arrhenian with addition of normative anorthite. The addition of water to melts with 10 and 20 wt% normative anorthite results in strong nonlinear decreases in viscosity. In the high viscosity range, the results for hydrous melts with 10% normative anorthite are adequately reproduced using the calcalkaline melt viscosity model of Hess and Dingwell (1996), whereas those for hydrous melts with 20 wt% normative anorthite are higher than the model predictions by amounts that depend on the water content. It appears that, at the higher temperatures anticipated for intermediate granitic magmatism, the calcalkaline model can adequately deal with up to 15 wt% normative anorthite in the melt composition in the range of temperatures relevant for intermediate magmas in nature.

Morphology-derived lava flow rheology is a frequently used tool in volcanology and planetary science to determine rheological parameters and deduce the composition of lavas on terrestrial planets and their moons. These calculations are usually based on physical equations incorporating 1) lava flow driving forces: gravity, slope and flow-rate and 2) morphological data such as lava flow geometry: flow-width, -height or shape of the flow outline. All available methods assume that no geometrical changes occur after emplacement and that the measured flow geometry reflects the lava's apparent viscosity and/or yield strength during emplacement. It is however well-established from terrestrial examples that lava flows may inflate significantly after the cessation of flow advance. This inflation affects, in turn, the width-to-height ratio upon which the rheological estimates are based and thus must result in uncertainties in the determination of flow rheology, as the flow height is one of the key parameters in the morphology-based deduction of flow properties. Previous studies have recognized this issue but, to date, no assessment of the magnitude of this error has been presented. This is likely due to a lack of digital elevation models (DEMs) at sufficiently high spatial and temporal resolution. The 2014/15 Holuhraun eruption in central Iceland represents one of the best monitored large volume (1.5 km 3 ) lava flow fields (85 km 2 ) to date. An abundance of scientific field and remote sensing data were collected during its emplacement. Moreover, inflation plays a key role in the emplacement dynamics of the late stage of the lava field. Here, we use a time series of high resolution DEMs acquired by the TanDEM-X satellite mission prior, during and after the eruption to evaluate the error associated with the most common methods of deriving lava flow rheology from morphological parameters used in planetary science. We can distinguish two dominant processes as sources of error in the determination of lava flow rheology from morphology 1) wholesale inflation of lava channels and 2) post halting inflation of individual lava toes. These result in a 2.4- to 17 - fold overestimation of apparent viscosity and a 0.7- to 2.4 - fold overestimation of yield strength. When applied in planetary sciences, this overestimation in rheological parameters translates directly to an overestimation of the respective lavas silica content. We conclude that, although qualitatively informative, morphological analysis is insufficient to discern lava rheology and composition. Instead, in-situ analysis together with high resolution remote sensing data is needed to properly constrain the compositions involved in planetary volcanism. [ABSTRACT FROM AUTHOR]

One of the most spectacular displays of nature is the eruptive behavior of active volcanoes. At one end of the spectrum of eruption styles is the slow effusive extrusion of [...]