Melting Temperature Of Ice Research Articles

Density isobar of water and melting temperature of ice: Assessing common density functionals.

We investigate the density isobar of water and the melting temperature of ice using six different density functionals. Machine-learning potentials are employed to ensure computational affordability. Our findings reveal significant discrepancies between various base functionals. Notably, even the choice of damping can result in substantial differences. Overall, the outcomes obtained through density functional theory are not entirely satisfactory across most utilized functionals. All functionals exhibit significant deviations either in the melting temperature or equilibrium volume, with most of them even predicting an incorrect volume difference between ice and water. Our heuristic analysis indicates that a hybrid functional with 25% exact exchange and van der Waals damping averaged between zero and Becke-Johnson dampings yields the closest agreement with experimental data. This study underscores the necessity for further enhancements in the treatment of van der Waals interactions and, more broadly, density functional theory to enable accurate quantitative predictions for molecular liquids.

Accuracy limit of non-polarizable four-point water models: TIP4P/2005 vs OPC. Should water models reproduce the experimental dielectric constant?

The last generation of four center non-polarizable models of water can be divided into two groups: those reproducing the dielectric constant of water, as OPC, and those significantly underestimating its value, as TIP4P/2005. To evaluate the global performance of OPC and TIP4P/2005, we shall follow the test proposed by Vega and Abascal in 2011 evaluating about 40 properties to fairly address this comparison. The liquid-vapor and liquid-solid equilibria are computed, as well as the heat capacities, isothermal compressibilities, surface tensions, densities of different ice polymorphs, the density maximum, equations of state at high pressures, and transport properties. General aspects of the phase diagram are considered by comparing the ratios of different temperatures (namely, the temperature of maximum density, the melting temperature of hexagonal ice, and the critical temperature). The final scores are 7.2 for TIP4P/2005 and 6.3 for OPC. The results of this work strongly suggest that we have reached the limit of what can be achieved with non-polarizable models of water and that the attempt to reproduce the experimental dielectric constant deteriorates the global performance of the water force field. The reason is that the dielectric constant depends on two surfaces (potential energy and dipole moment surfaces), whereas in the absence of an electric field, all properties can be determined simply from just one surface (the potential energy surface). The consequences of the choice of the water model in the modeling of electrolytes in water are also discussed.

Mechanical Characterization of Vial Strain During Freezing and Thawing Operations Using Amorphous Excipients

The purpose of this study was to investigate the mechanical stresses and strains acting on pharmaceutical glass tubing vials during freezing and thawing of model pharmaceutical formulations. Strain measurements were conducted inside of a laboratory-scale freeze-dryer using a custom wireless sensor. In both sucrose and trehalose formulations at concentrations between 5 % and 20 % w/v, the strain measurements initially increased before peaking in magnitude at temperatures close to the respective glass transition temperatures of the maximally freeze concentrated solutes, Tg’. We attribute this behavior to a shift in the mechanical properties of the frozen system from a purely elastic glass below Tg’ to a viscoelastic rubber-like material above Tg’. That is, when the interstitial region becomes mechanically compliant at temperature above Tg’. The outputs were less predictable below 5 % w/v and tended to exhibit two separate peaks in strain output, one near the equilibrium melting temperature of pure ice and the other near Tg’. The peaks merged at concentrations between 4 and 5 % w/v where the largest strain magnitude was observed. The strain on primary packaging has traditionally been applied to evaluate the risk of damage or breakage due to, for example, crystallization of excipients. However, data collected during this study suggest there may be utility in formulation design or as a process analytical technology to minimize potentially destabilizing stresses and strains in the frozen formulation.

Extended depth-of-field resolution enhancement microscopy imaging for neutralizing the impact of mineral inhomogeneous surface

<p>One of the most fundamental experimental methods in geoscience is to observe minerals under high magnification objectives. However, uneven microsurfaces in thin sections occur due to the irregular constituent distribution and varying hardness of minerals in natural rocks. Consequently, the conflict between large depth-of-field (DOF) and high-resolution in microscopy imaging leads to random out-of-focus issues when observing thin sections with high resolution microscopy. Although existing super-resolution algorithms promise to improve visual performance, reconstructing images with both large DOF and high-resolution simultaneously remains challenging. We address this problem by guiding the networks with optical information. Utilizing DOF information from low-resolution data, we propose an optically induced generative adversarial network (OIGAN) to neutralize the impact through computational imaging. In OIGAN, optical DOF information from low-resolution data facilitates to achieve spatial-adaptive extended-DOF resolution enhancement imaging, without incorporating extended DOF high-resolution data for supervision. The approach, trained and evaluated on the dataset with 233,156 images (115,346 pairs of low- and high-resolution data), outperforms four comparison methods on various minerals and optical conditions, leading to at least 1.54dB increase on peak signal-to-noise ratio (PSNR). Specifically, OIGAN significantly improves the accuracy of fluid inclusion ice-melting temperature measurement, reducing mean error by 65%, and enhances mineral classification accuracy with 1.5%~15% increase. OIGAN offers an insight of integrating physical knowledge into neural networks, facilitating self-identification of minerals, automatic microthermometry of fluid inclusions and other geoscience tasks via microscopy.</p>

Mars' atmosphere, volatiles, and climate as the sun heats up over the next 6 billion years

As the solar luminosity continues to increase over the next 6 billion years, the Martian surface will heat up to above the melting temperature of water ice. Water ice currently in the polar caps and ground ice will melt, potentially repopulating crater lakes or a very small ocean, with the abundance possibly enhanced due to diffusion upward of water currently locked in the deep crust. CO2 adsorbed in the regolith and locked up in the south-polar ice cap will diffuse into the atmosphere, providing up to 50 mbar total pressure; this will further increase the temperature via greenhouse warming. There are two end-member scenarios for the climate under these conditions: (i) Surface water could drive an atmospheric water cycle somewhat analogous to present-day Earth's, which would create a global clement climate conducive to the existence of widespread surface life. (ii) The widespread presence of liquid water could cause CO2 to form carbonate minerals and H2O to hydrate surface/subsurface minerals (or allow H released from water to escape to space), and CO2 and H2O could be lost to space, leaving Mars with a dry environment. The climate could end up between these end-members and also could vary with time. This uncertain climate end state informs our view that exoplanet evolution and habitability can be driven by endogenous processes associated with a terrestrial planet as well as by the ability of EUV and a stellar wind from the host star to strip away atmosphere.

Molecular simulation of the confined crystallization of ice in cement nanopore.

Freezing of water under nanoconfinement exhibits physical peculiarities with respect to the bulk water. However, experimental observations are extremely challenging at this scale, which limits our understanding of the effect of confinement on water properties upon freezing. In this study, we use molecular dynamic simulations to investigate how confinement affects the kinetics of growth of ice and the thermodynamic equilibrium of ice-liquid coexistence. TIP4P/Ice water model and CSH-FF model were applied to simulate ice crystallization in a confined cement system at temperatures down to 220K. We adapted an interface detection algorithm and reparameterized the CHILL/CHILL+ algorithm to capture ice growth. The confinement leads to a shift of the maximum growth rate of ice to a higher temperature than for bulk water. Both the confinement and surface impurities contribute to slowing down the ice growth. For the ice-liquid coexistence at equilibrium, we derive a formulation of Thomson's equation adapted to statistical physics quantities accessible by molecular simulation, and we show that this adapted equation predicts accurately the melting line of bulk and confined ice Ih as a function of pressure. The confinement decreases systematically the melting temperature of ice of about 5K compared with bulk ice Ih. A premelted water film about 1nm thick is observed between the solid wall and ice, and its thickness is found to decrease continuously as temperature is lowered. We note that the surface impurities are key to the formation of the premelted water nanofilm when the temperature is lower than 250K.

Simulating a flexible water model as rigid: Best practices and lessons learned.

Two ways to create rigid versions of flexible models are explored. The rigid model can assume the Model's Geometry (MG) as if the molecule is not interacting with any other molecules or the ensemble averaged geometry (EG) under a particular thermodynamic condition. Although the MG model is more straightforward to create, it leads to relatively poor performance. The EG model behaves similarly to the corresponding flexible model (the FL model) and, in some cases, agrees even better with experiments. While the difference between the EG and the FL models is mostly a result of flexibility, the MG and EG models have different dipole moments as a result of an effective induction in the condensed phase. For the three water models studied, the property that shows the most difference is the temperature dependence of density. The MG version of the water model by adaptive force matching for ice and liquid does not possess a temperature of maximum density, which is attributed to a downshift of the putative liquid-liquid phase transition line, leading to the hypothesized second critical point of liquid water to manifest at negative pressure. A new three-phase coexistence method for determining the melting temperature of ice is also presented.

Nature and conditions of gold mineralization at the Tau deposit, Mupane mine, Tati Greenstone Belt, Botswana: Evidence from fluid inclusion and arsenopyrite geothermometer

AbstractThe gold mineralization at the Tau deposit in northeastern Botswana can be distinguished into two stages. The first stage of mineralization consists of invisible gold associated with early, sulfur‐rich arsenopyrite (Apy1). The second stage is characterized by native gold associated with late, sulfur‐poor arsenopyrite (Apy2). This study aims to constrain the nature of the ore‐forming fluid at the Tau deposit on the basis of fluid inclusion microthermometry and arsenopyrite geothermometry. Quartz crystals closely associated with gold‐bearing sulfides (Apy1) from the host rock host three types of fluid inclusions occurring in the same assemblages: Type I, two‐phase aqueous fluid inclusions, Type II three‐phase aqueous‐carbonic fluid inclusions and Type III one‐ or two‐phase CO2‐rich fluid inclusions. Microthermometric and Raman spectroscopic studies revealed the dominance of coexisting H2O+NaCl (Type I) and CO2N2CH4 (Type III) fluid inclusions. The coexisting Type I and Type III fluid inclusions could represent products of the immiscibility of a homogenous H2OCO2NaClN2CH4 primary ore fluid. The salinity of Type I (calculated from melting temperature of ice) and Type II (calculated from dissolution temperature of clathrate) fluid inclusions vary from 3.4 to 9.2 wt% NaCl equiv. and 5.8 to 9.8 wt% NaCl equiv., respectively. The overall fluid inclusion salinity range (<10 wt% NaCl equiv.) and gas compositions of fluids suggest that the primary ore‐forming fluid at the Tau deposit was of low salinity and H2OCO2N2CH4NaCl composition. Integration of fluid inclusion microthermometry and arsenopyrite geothermometer results suggest that the first stage and second stages of gold mineralization and the associated alteration at the Tau deposit occurred at pressure and temperature conditions of 75–145 MPa and 290–370°C and 85–160 MPa and 330–370°C, respectively. These results suggest that there was an increase in temperature from the first stage to the second stage of mineralization, resulting in the recrystallization of invisible gold‐bearing arsenopyrite in the first stage to form native gold‐bearing arsenopyrite in the second stage. Fluid composition and the estimated physico‐chemical conditions at the Tau deposit confirm that gold was transported as reduced bisulfide complexes and initial gold deposition was likely caused by a reduction in sulfur contents as a result of sulfidation reactions and pressure‐induced phase separation (fluid immiscibility).

Inhibition of ice recrystallization by tamarind (Tamarindus indica L.) seed polysaccharide and molecular weight effects

This study aimed to investigate the inhibition effects of tamarind seed polysaccharide (TSP) on ice recrystallization and to figure out its possible molecular weight-dependent effects. TSP fractions (2412.38–20.75 kDa) were prepared while preserving the natural structure. Ice recrystallization was effectively inhibited by TSP. Decreasing the molecular weight to a certain range, such as 224.04 kDa and 90.41 kDa, could enhance the activity of TSP due to the reduction of self- and intermolecular aggregation. Adding TSP into water decreased the melting temperature of bulk ice. Raman spectra showed that partial group vibrations or deformations of TSP molecules were restricted upon solution freezing and also revealed a destructuring effect of TSP on the H-bond network of water. These findings suggested the potential of TSP as a novel food cryoprotectant and help produce TSP fractions with enhanced activity, and shed new light on understanding the antifreeze mechanism of natural polysaccharides.

Relationships between phase transition and quality characteristics of cooked rice during storage

The objective of this study was to determine crystalline structures, phase transitions, textural properties, and morphological characteristics of cooked rice with different amylose contents during storage at 4 °C for 14 days. Moisture content of cooked rice decreased from 64.8% to 60.2% during storage. Relative crystallinity increased during storage, indicating an increase in ordered structure by starch recrystallization. During the storage, ice freezing and ice melting enthalpies of cooked rice decreased and glass transition temperature ( T g ′) increased. Inner structure of cooked rice showed smaller holes and a thicker surrounding matrix in waxy or non-waxy rice varieties and polyhedral structure in high-amylose variety. Ice melting enthalpy of cooked rice was positively and negatively correlated with hardness and adhesiveness, respectively. T g ′ was positively correlated with adhesiveness. These results indicate that phase transitions of cooked rice with different amylose contents were significantly related to their crystalline structures, morphologies, and textures during storage. • Relationship between phase transition and quality characteristics of cooked rice was investigated. • Cooked rice with higher amylose had a thick matrix with a rod-shaped structure during storage. • Cooked rice with high palatability had low relative crystallinity and ice melting temperature. • Phase transition parameters of cooked rice were correlated with textural properties.

LBM study of ice nucleation induced by the collapse of cavitation bubbles

In this study, we extended the conventional lattice Boltzmann method (LBM) to numerically examine ice nucleation induced by the collapse of a cavitation bubble. Specifically, a pseudo-potential multi-relaxation-time lattice Boltzmann method (MRT-LBM) coupled with a thermal LBM and a criterion for pressure-dependent ice nucleation onset was developed to investigate the cavitation bubble dynamics including growth and collapse, and the subsequently induced ice nucleation. Using the present model, the water vapour-liquid coexistence curve was extended to temperatures lower than 42% of its critical point, excellently matching the Maxwell construction curve. Two practical application scenarios of ice nucleation were investigated: I, near a solid boundary and II, within a pressurised space. Effects of key system parameters including the stand-off distance (λ), differential pressure (Δp) and initial bubble size (R0) on the maximum collapse pressure (pmax) were examined. The results show that under the same conditions, a much higher pmax is generated in scenario II than that in scenario I, thus more readily initialises ice nucleation. After initialisation, part of the initially formed ice melts when the local temperature exceeds the ice melting temperature due to the rapid dissipation of pressure wave. To ensure the complete freezing of water, a large initial supercooling is required for scenario II.

Ultralow Melting Temperature of High-Pressure Face-Centered Cubic Superionic Ice.

Superionic ice with oxygen in a face-centered cubic (fcc) sublattice is ascribed to the origin of magnetic fields of Uranus and Neptune, since the melting temperature (Tm) of fcc-superionic ice is believed to be higher than the isentropes of ice giants. However, precisely measuring the fcc-superionic phase experimentally remains a difficult task. The majority of the systematic investigations of its Tm were performed using perfect oxygen fcc-sublattice computations, which could result in superheating and overestimation of Tm. On the basis of the ab initio molecular dynamics method and the model with H2O vacancy, we avoid superheating and obtain a much lower Tm than previous reports, indicating that fcc-superionic ice cannot exist in the interiors of Uranus and Neptune. Further simulations with the two-phase method justify the conclusion. The results suggest that superheating should be seriously treated when simulating the phase diagram of other hydrogen-related superionic states, which are widely used to understand the properties of ice giants, Earth, and Venus.

Research and application of ice melting power supply for OPGW

In recent years, the ice melting techniques for power transmission line has been making great achievements in China, but none of them can be applied to the deicing of OPGW (optical fiber composite overhead ground wire). OPGW contains communication optical fiber, which has special structure and high requirements for ice melting temperature. At present, deicing technologies can not be directly applied to the deicing of OPGW, and icing of OPGW becomes a technical challenge. Based on the DC ice melting technology and considering the characteristics of OPGW line, this paper develops an adjustable voltage DC ice melting power supply to meet the needs of OPGW ice melting. The fuzzy PID control method of DC ice melting device is simulated and the prototype is trial manufactured successfully. A promising ice melting performance is obtained through the field engineering test.

Melting points of water models: Current situation.

By using the direct coexistence method, we have calculated the melting points of ice Ih at normal pressure for three recently proposed water models, namely, TIP3P-FB, TIP4P-FB, and TIP4P-D. We obtained Tm = 216K for TIP3P-FB, Tm = 242K for TIP4P-FB, and Tm = 247K for TIP4P-D. We revisited the melting point of TIP4P/2005 and TIP5P obtaining Tm = 250 and 274K, respectively. We summarize the current situation of the melting point of ice Ih for a number of water models and conclude that no model is yet able to simultaneously reproduce the melting temperature of ice Ih and the temperature of the maximum in density at room pressure. This probably points toward our both still incomplete knowledge of the potential energy surface of water and the necessity of incorporating nuclear quantum effects to describe both properties simultaneously.

Gold Nanoprobes Exploring the Ice Structure in the Aqueous Dispersion of Poly(Ethylene Glycol)-Gold Hybrid Nanoparticles.

Ice structures and their formation process are fundamentally important to cryobiology, geoscience, and physical chemistry. In this work, we synthesized gold nanoprobes by grafting water-soluble polyethylene glycol (PEG) onto spherical gold nanoparticles and analyzed the structure of ice formation in the vicinity of the resulting hybrid PEG-Au nanoparticles (AuPEGNPs). Temperature-dependent in situ small-angle X-ray scattering (SAXS) indicated that AuPEGNPs, like PEG, caused the formation of bulk spherulite ice. Unlike for PEG, we observed the formation of lamellar ice with a periodicty of 4.6 nm, which is thermodynamically less stable than the bulk form. The lamellar ice formed after AuPEGNP agglomeration during cooling at -19 °C, and it remained during subsequent heating from -20 to -11 °C and melted at around -10 °C, far below the melting temperature of bulk ice. We explain different effects of AuPEGNP and free PEG on ice formation by the topological differences. The highly concentrated PEG chains on the agglomerated Au cores lead to the formation of PEG-hydrates that assemble into lamellar ice with a periodicity of 4.6 nm.

Quasi-water layer sandwiched between hexagonal ice and wall and its influences on the ice tensile stress.

The presence of a quasi-water/premelting layer at the interface between wall and ice when the temperature (T) is below the melting point was extensively observed in experiments. In this work, molecular dynamics simulations are performed to analyze the underlying physics of the quasi-water layer and the effects of the layer on the ice tensile stress. The results indicate that each molecule and its four nearest neighbours in the quasi-water layer representing an equilibrium structure gradually form a tetrahedral ice-like arrangement from an unstructured liquid-like structure along the direction away from the wall. The average density of the quasi-water layer is equal to or higher than the bulk density of water at T ≥ 240 K or T ≤ 240 K respectively, and reaches 1.155 g cm-3 at T = 210 K, suggesting a structural correlation with the high-density liquid phase of water. Depending on the temperature and wall wettability, the thickness of the quasi-water layer (Hq) ranges from ∼2 Å to ∼25 Å. For prescribed hydrophilic walls, Hq increases monotonically with temperature, and is almost proportional to(Tm - T)-1/3, where Tm is the melting temperature of ice. Hq keeps an almost constant value (2 Å) as the temperature increases and rises sharply after passing a threshold temperature of T ≈ 250 K. In the joint effects of the wall wettability and quasi-water layer's thickness, the ice tensile stress decreasing monotonically at a larger temperature shows an upward trend and then reduces to almost a constant value as the wall changes from a hydrophobic to a hydrophilic one. The results reveal the potential development of anti-icing/de-icing techniques by heating the wall or modifying its surface to increase Hq.

Fluid Inclusion Study of Epithermal Quartz Veins from the Kyaukmyet Prospect, Monywa Copper-Gold Ore Field, Central Myanmar

The Kyaukmyet prospect is located near the main ore bodies of the Kyisintaung and Sabetaung high-sulfidation Cu-Au deposits, Monywa copper-gold ore field, central Myanmar. Lithologic units in the research area are of mainly rhyolite lava, lapilli tuff and silicified sandstone, mudstone and siltstone units of Magyigon Formation which hosted to be polymetallic mineralization. Our field study recorded that epithermal quartz veins are hosted largely in rhyolite lava and lapilli tuff units. Those quartz veins show crustiform, banded (colloform), lattice bladed texture and comb quartz. The main objectives of the present research in which fluid inclusion studies were considered to conduct the nature, characteristics and hydrothermal fluids evolution from the epithermal quartz veins. In this research, there are three main types of fluid inclusions are classified according to their phase relationship (1) two-phase liquid-rich inclusions, (2) the coexisting liquid-rich and vapor-rich inclusions, and (3) only vapor-rich inclusions. Microthermometric measurements of fluid inclusions yielded homogenization temperatures (Th) of 148–282 °C and final ice-melting temperature (Tm) of -0.2°C to -1.4°C . The value of (Tm) are equal to the salinities reaching up 0.35 to 2.07 wt % NaCl equiv. respectively. Estimation formation temperature of the quartz veins provide 190°C and 210°C and paleo-depth of formation are estimated to be between 130m and 210m. Petrography of fluid inclusion and microthermometric data suggest that fluid boiling as well as mixing processes were likely to be happened during the hydrothermal fluid evolution at the Kyaukmyet prospect. According to the characteristics of many parameters including petrography of fluid inclusion, microthermometric data, paleo-depth, evidence of quartz vein textures and types of hydrothermal alteration from the Kyaukmyet prospect allows to interpret these data to be the low-sulfidation epithermal system.

Melting temperature of ice and total gas content of water at the ice-water interface above subglacial Lake Vostok

It is generally assumed that the gas composition and the total gas content of Lake Vostok’s water are, to a large extent, governed by the budget of atmospheric gases entering the lake together with glacier ice melt, mostly in its northern part. Since the ice accretion that prevails in the south of the lake leads to the exclusion of gases during the freezing process, these gases can build up in the lake water. Earlier theoretical works [2, 3] have demonstrated that about 30 water residence times are required to attain equilibrium between gases in solution and those in a hydrate phase, which sets the upper bounds of concentrations of nitrogen and oxygen dissolved in sub-ice water (~2.7 g N2 L–1 and ~0.8 g O2 L–1). Here we attempt to estimate the real gas content of the lake water based on the link between the pressure melting temperature of ice and the concentration of gases dissolved in the liquid phase [2]. We use the stacked borehole temperature profile extended to 3753 m depth and the measurements of temperature of sub-ice water that entered the borehole after the second unsealing of Lake Vostok to estimate the melting temperature of ice (–2.72 ± 0.1 °C) at the ice sheet-lake interface (depth 3758.6 ± 3 m, pressure 33.78 ± 0.05 MPa). The gas content of the near-surface layer of lake that corresponds to this melting temperature is calculated to be 2.23 g.L–1, meaning that the concentration of dissolved oxygen must be as high as 0.53 g.L–1, i. e. one-two orders of magnitude higher than in any other known water bodies on our planet. The inferred gas content of sub-ice water is, by a factor of 1.6, lower than the maximal solubility of air in water in equilibrium with air hydrate, though it is still higher, by a factor of 19, than the total air content of melting glacier ice. The relatively low concentration of dissolved air in the near-surface layer of the lake revealed in this study provides a new experimental constraint for understanding the gas distribution in Lake Vostok as affected by the circulation and mixing of water beneath the ice sheet.

Precision of determination of thawing depth of the frozen rocks

An important quantity determining the choice of technical solutions in design of both surface and underground structures in the permafrost area is the thawing depth of the rocks. To obtain simple analytical relations to determine the thawing depth over time, a simple assumption is used: that the initial temperature of the rocks is equal to the melting temperature of ice. The aim of the present work was the assessment of impact of this assumption on the forecast precision. For a quantitative assessment, a simple typical formula recommended by construction norms was used. Functional dependence of the density of the rocks and their heat capacity on the fraction of ice content was considered in the formulas. A rock consisting of a combination of quartz sand and ice was used as an example.Multiple variant calculations were done according to the formulas and their results presented in the form of charts. It was shown that the relative error in determination of thawing depth depends solely on the Stefan criterion and is independent of the thawing duration, thermal conductivity coefficient of the thawing rocks and the air temperature during the thawing. A relation was obtained which allows to quickly assess at which initial values (temperature and ice content of the frozen rocks) it is possible to use the formulas obtained from the simplified calculation models with the assumption that the temperature of the rocks is equal to the melting temperature of ice.

Fluid evolution from quartz veins in micaschists from the thermal aureole around the Acari batholith, Northeast Brazil

Micaschists that host the Acari batholith (Ediacaran age, 572 to 577 My) are characterized by a large number of quartz veins. The veins are more abundant in higher-temperature metamorphic zones and, together with lower metamorphic zones, form an aureole centered in the batholith. Most of the fluid inclusions are two-phase (H2O-CO2 and liquid/vapor), but three-phase varieties (liquid/vapor/salt cubes; liquid/liquid/vapor) occur locally. The analyzed veins come from the biotite + chlorite + muscovite, biotite + garnet, cordierite + andalusite, and cordierite + sillimanite metamorphic zones. CO2 melting temperatures (TmCO2) vary from -62.6 to -56.7°C, suggesting CH4 and/or N2. Eutectic temperatures (Te) in quartz veins show average values of -30.8°C in the biotite + chlorite + muscovite and biotite + garnet zones, and -38.6°C in the cordierite + andalusite and cordierite + sillimanite zones. Ice-melting temperatures (Tmice) are lower in the higher-temperature metamorphic zones. The mode values are -3.8, -5.5, -5.6, and -7.3°C, corresponding respectively to the biotite + chlorite + muscovite, biotite + garnet, cordierite + andalusite, and cordierite + sillimanite zones. A fluid characterized by the H2O-Na-Cl (KCl)-MgCl2-FeCl2-CaCl2 system is defined by: Tmice from near -1.9 to -32°C, the presence of salt cubes mainly in the cordierite + andalusite and cordierite + sillimanite zones, and recorded eutectic temperatures (Te) from -16.5 to -59.1°C. In addition, total homogenization temperatures (Tht) ranging from 117 to 388°C were obtained for primary aqueous fluid inclusions. This indicates a long period of fluid circulation under conditions of falling temperatures. Our results are consistent with an increase in the salinity of the aqueous fluid across the thermal aureole toward the granitic batholith.