Fluid inclusion homogenization temperature

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

A few studies reported considerable intracrystalline isotopic variations within millimetre-sized saddle dolomite crystals. For example, a 1.4%o variation in 6 0 and a 0.7%o variation in 5 C were found in isotopically zoned saddle dolomite crystals from Cretaceous carbonates of south Texas (Woronick Land, 1985). In another study, a 5.2%o decrease in 6 0 (-6 to -11.2%o) and a systematic increase in fluid inclusion homogenization temperature (127-146°C) were reported for a single saddle dolomite crystal in Devonian rocks of Canada (Kaufman et al., 1990). Further, Spangen-berg et al. (1995) reported preliminary stable isotope results for intracrystalline heterogeneities in white sparry dolomite (largely equivalent to saddle dolomite) in samples from a Peruvian MVT... 

One of the most extensively studied regions where saddle dolomite is widespread is the Western Canada Sedimentary Basin and adjacent Rocky Mountain thrust belt. Along an E-W traverse from the deeply buried thrust portion of the basin on to the foreland, the 6 0 values of saddle dolomite in Cambrian and Devonian carbonate strata increase, whereas fluid inclusion homogenization temperatures and Sr/ Sr ratios decrease (Qing Mount joy, 1992, 1994a) (Fig. 8). According to a... 

Fig. 10. Frequency histogram of primary fluid inclusion homogenization temperatures reported for saddle dolomite. Horizontal arrows indicate literature sources that reported a range of values only. Data from Coniglio Williams-Jones (1992) are mostly from inclusions of secondary or indeterminate origin and are shown for comparison.

Fig. 13. Fluid inclusion homogenization temperatures for the middle (S2) and late generations (S3) of the Tirrawarra Sandstone siderites. The fluid inclusions are considered to be of primary origin, and did not experience stretching. S2 formed at much lower temperatures than S3.

Figure 8. Fluid inclusion homogenization temperatures from the Death Valley salt core, depths of 186 m to 109 m ( 192 ka to I20ka). Ranges of fluid inclusion homogenization temperatures for different stratigraphic intervals are plotted. Note that the range of homogenization temperatures in the salt pan facies is higher than ip the perennial lake facies. (From Roberts et al., 1997, Fig. 14. p, 119).

In order to use fluid inclusions from lacustrine halites for detailed paleoclimate interpretations, it is important to have air temperature and water temperature records from the study area. The modern records serve as the reference against which fluid inclusion homogenization temperatures are compared. Information on the temperatures of saline lakes in Africa and Canada may be found in Hammer (1986). Other sources of saline lake temperatures are Carpelan (1958) for the Salton Sea, California, Eubank Brough (1980) for Great Salt Lake, Utah Smith et al. (1987) for Owens Lake, California, Gavrieli et al. (1989) for the Dead Sea, Israel and Jordan, and Casas et al. (1992) for Qaidam Basin, Qinghai Province, China. 

Fig. 4.10 Conductive cooling combined with mixing to cause the precipitation of amorphous silica in chimneys from two different fluids at Guaymas Basin (Peter and Scott 1988). As in Figure, quartz does not precipitate for kinetic reasons nor does amorphous silica by simple mixing of the vent fluid with ambient seawater (line A). Amorphous silica does precipitate as a consequence of conductive cooling and mixing. The relative amounts of mixing may be determined accurately from the intercepts of the fluid inclusion homogenization temperatures with the silica saturation curve (lines B-F) (Scott 1997)...

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 1.36. 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... 

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. 

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).

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).

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... 

The ranges of /sj and temperature for epithermal Au-Ag vein-type deposits in Japan have been clearly defined based on the chemical composition of sphalerite and electrum, and homogenization temperatures of fluid inclusions (Shikazono, 1985d). Values of /s for the Tsugu deposit are lower than the typical ranges of values for the epithermal Au-Ag vein-type deposits in Japan (Fig. 1.176). Such a low f 2 is in accord with the high Hg content of electrum in the Tsugu deposit. 

Figure 1.178 represents a comparison between the stannite-sphalerite temperatures and homogenization temperatures of fluid inclusions or sulfur isotope temperatures. It can be seen in Fig. 1.178 that Nakamura and Shima s geothermometer would be rather consistent with the temperature estimated based on the fluid inclusions or sulfur isotope studies. It is notable that almost all stannite-sphalerite temperatures are within 30°C of average homogenization temperatures and sulfur isotope temperatures. 

The Ag content of electrum is very low (Fig. 1.186) and FeS content of sphalerite is high (6-17 FeS mol%) (Fig. 1.187) (Shikazono and Shimizu, 1987). Combining these compositional data with homogenization temperatures of fluid inclusions, /sj of ore fluids was estimated (Fig. 1.188). Estimated /sj range is lower than that of epithermal Au-Ag vein ore fluids. 

The fluid inclusion studies of hot spring-type deposits (Takenouchi, 1981) show a wide range of homogenization temperatures in a given quartz crystal which suggests the boiling of ore fluids. These fluid inclusion studies demonstrate that the hot spring-type formed under shallow depth from the surface. 

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