Homogenization temperature

Most room models contain only one zone air node, thus assuming perfect mixing of the zone air and a homogenous temperature distribution in the space. Spatial temperature variations, such as vertical temperature gradients, are not considered. For specific applications such as displacement ventilation or atria, models with several zone air nodes in the vertical direction have been developed. ... 

At low temperatures the average temperatures ealeulated from the individual measurements eorresponded to the temperature setting. They were appreeiably lower at higher temperatures and it was found that the temperature setting eorresponded to the highest temperature that eould be reaehed in the individual measurements. It was also evident that the edge of the hotplate was eolder than the middle, i.e. the effeetive measured temperature was not the same everywhere over the surface of the hotplate a homogeneous temperature distribution is most likely to be found in the center of the plate. 

Toward the end of the reaction, the mixture becomes quite viscous. Unless the stirring assembly is capable of mixing material at the flask walls, homogeneous temperature control cannot be guaranteed. 

Fig. 1.15. Diagram showing the homogenization temperature of fluid inclusions vs. the iron content of the host sphalerite growth zone for sample locality NJP-X on the OH vein. The line shows the predicted iron content of the sphalerite if the sulfur fugacity of the system had been buffered by the triple point — Fe-chlorite (daphnite), pyrite, hematite (Hayba et al., 1985).

Marutani and Takenouchi (1978) clarified the variations in homogenization temperature and salinity of inclusion fluids in quartz from stockwork siliceous orebodies at the Kosaka mine (Fig. 1.35 Urabe, 1978). They showed that the temperature decreases stratigraphically upwards from stockwork ore zone (280-320°C) to bedded ore zone (260-310°C). Pisutha-Arnond and Ohmoto (1983) carried out fluid inclusion studies of the stockwork siliceous ores from five Kuroko deposits (Kosaka, Fukazawa, Furutobe, Shakanai, and Matsumine) and revealed that black ore minerals (sphalerite, galena, barite) and yellow ore minerals (chalcopyrite, quartz) formed at 200-330°C and 330 50°C, respectively, and salinities of the ore fluids remained fairly constant at about 3.5-6 equivalent wt% NaCl. They analyzed fluids extracted from sulfides and quartz Na = 0.60 0.16 (mol/kg H2O), K = 0.08 0.05, Ca = 0.06 0.05, Mg = 0.013 0.008, Cl = 0.82 0.32, C (as CO2) = 0.20 0.15 and less than 6 ppm each for Cu, Pb, Zn and Fe. 

Figure 1.35. Summarized results of homogenization temperature determination in quartz from Uwamuki No. 4 Orebody shown for Kuroko-type (BSO) and Oko-type (YSO), and siliceous ores and for each level (Marutani and Takenouchi, 1978).

Figure 1.36. Homogenization temperature and salinity of inclusion fluids (Pisutha-Arnond and Ohmoto, 1983).

Since temperature of formation of carbonates can be estimated from homogenization temperature of fluid inclusions in carbonates, we can place a limit of CO2 from the above equilibrium relationships. The estimated CO2 range is 1-0.01 mol/kgH20. 

These predictions are generally in agreement with the observations homogenization temperatures of fluid inclusions in quartz from siliceous ore zone and in barite from black ore zone in the Kuroko deposits is relatively high, ranging from 350 to 250°C, and low, ranging from 250 to 150°C, respectively. 

The fluid inclusions can be divided into two types vapor- and liquid-rich fluid inclusions. The filling degree of fluid inclusions from some samples from the silicified and alunite zones is variable and homogenization temperatures vary widely. This indicates... 

Substantial amounts of homogenization temperature data on the Neogene vein-type deposits in Japan are available (e.g., Enjoji and Takenouchi, 1976 Shikazono, 1985b) and they are summarized in Fig. 1.87. 

Homogenization temperatures vary widely within a given deposit type and even within a single deposit. However, the ranee of homogenization temperatures differs according to the type of deposit 190°Cll 250°C for Au-Ag-rich deposits, 200°C to 250°C for Pb-Zn-Mn-rich deposits, and 2(X)° to 350°C for Cu-Pb-Zn-rich deposits (Fig. 1.87) (Shikazono, 1985b). 

The effect of pressure is negligible. These epithermal Au-Ag vein-type deposits have formed in a shallow and low-pressure environment and pressure correction, such that any correction to the homogenization temperatures will be small (probably less than 20°C). 

The good correlation between homogenization temperatures and electrum-sphalerite temperatures suggests several points (1) the uncertainties of electrum-sphalerite temperatures are less than 20° to 30°C, even at temperatures from ca. 180° to 300°C, (2) the electrum-sphalerite-pyrite-argentite assemblage was formed close to equilibrium in Japanese epithermal Au-Ag vein-type deposits, and (3) the pressure corrections to homogenization temperatures for Japanese epithermal Au-Ag vein-type deposits is small, less than 20°C to 30°C. 

Sulfur fugacity (/s ) As will be mentioned in section 2.4.3, fs2 can be estimated based on the Ag content of electram coexisting with argentite (or acanthite), the FeS content of sphalerite coexisting with pyrite and temperature estimated from homogenization temperatures of fluid inclusions. 

Oxygen fugacity (fot)- The /oj-pH diagrams (Figs. 1.90 and 1.91) were constructed at 200°C and 250°C based on the homogenization temperatures and electrum-sphalerite temperatures (Shikazono, 1985d). 

Figure 1.99. Estimated /CO2-temperature ranges from anaytical data on fluid inclusions and homogenization temperatures (Shikazono, 1986). T Taishu (Pb, Zn), O Ohizumi (Cu, Pb, Zn), Y Yatani (Pb, Zn), Os Osaiizawa (Cu, Pb, Zn), H Hosokura (Pb, Zn), C Chitose (Au, Ag), S Seigoshi (Au, Ag).

Figure 1.100. Typical /coj-temperature ranges for Au-Ag-rich, Pb-Zn-Mn-rich, and Cu-Pb-Zn-rich vein-type deposits estimated from gangue mineral assemblages, homogenization temperatures of fluid inclusions, and thermochemical calculations (Shikazono, 1985b).

Temperatures of formations of the Te-type and Se-type epithermal gold deposits estimated from fluid inclusion homogenization temperatures (Shikazono et al., 1990)... 

Figure 1.128. Plots of homogenization temperature against salinity of fluid inclusions from the Ohe (Mn-Pb-Zn), Toyoha (Pb-Zn-Mn), and Fujigatani-Kiwada (W) deposits (Shibue, 1991).

Oxygen isotopic fractionation factors used for the calculation were taken from Taylor (1997). Initial 8 0 value of hydrothermal solution (0%o) was estimated from 8 0 values of K-feldspar and quartz in the veins and homogenization temperatures (Shikazono and Nagayama, 1993), and that of groundwater (—7%c) was estimated from meteoric water value of the south Kyushu district (—7%c) (Matsubaya et al., 1975). 

The temperature of the initial hydrothermal solution is assumed to be 250°C from homogenization temperature of fluid inclusions in vein quartz (Shikazono and Nagayama, 1993). 

Available homogenization temperatures of fluid inclusion from the base metal vein-type, Au-Ag vein-type, and Kuroko deposits are summarized in Fig. 1.152. 

Salinity (NaCl equivalent concentration) of inclusion fluids is 1-6 wt%, 1-14.5 wt% and 0-3 wt% for Kuroko deposits, base metal vein-type deposits, and Au-Ag vein-type deposits, respectively. These data clearly demonstrate that the salinity of inclusion fluids for the base metal-rich deposits (base metal vein-type deposits, Kuroko deposits) is higher than that of the Au-Ag vein-type deposits, while homogenization temperatures of fluid inclusion for these three types of ore deposits do not show a wide... 

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