Low-sulfidation type Au–Ag mineralization at Bergama, Izmir, Turkey

Yılmaz, Hüseyin; Oyman, Tolga; Arehart, Greg B.; Çolakoğlu, Ali Rıza; Billor, Zeki

doi:10.1016/j.oregeorev.2006.10.007

Cited by 57 publications

(15 citation statements)

References 46 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The Ag/Au ratio of the mineralized veins and breccias is very variable (between 0.1 and 56, ESM Table 2). These low to high Ag/Au ratios are consistent with low-and intermediate-sulfidation epithermal deposits (Einaudi et al 2003;Yilmaz et al 2007Yilmaz et al , 2010. …”

Section: Geochemistry Of Hydrothermal Alterationsupporting

confidence: 62%

“…Therefore, crystallinity variation in illite can be related to gold distribution within alteration zones and provide vectors to high-grade mineralization at Chah Zard (e.g., Davies 2002). The temperature estimates at Chah Zard (140°C to 310°C) are typical of low-to intermediatesulfidation epithermal mineralization noted elsewhere (e.g., Brown 1978;Henley and Ellis 1983;Reyes 1990;White and Hedenquist 1995;Yilmaz et al 2007Yilmaz et al , 2010. The presence of a high temperature part to the system suggests porphyry-related gold potential at depth (e.g., Yilmaz et al 2010).…”

Section: Discussionmentioning

confidence: 95%

“…The presence of adularia associated with ore-grade zones suggests that boiling has occurred (Brown and Ellis 1970;Brown 1978;Henley 1985;Hedenquist 1990;Dong and Morrison 1995). In the margins of the deposit, clay mineralogy is identified as interlayered illite-smectite and chlorite (Kouhestani 2011) suggesting lower temperatures (140°C to 240°C, Henley and Ellis 1983;Hedenquist 1990;Yilmaz et al 2007Yilmaz et al , 2010. The decrease in the illite crystallinity could be due to lower permeability and fluid flux in the distal parts of the system.…”

Section: Discussionmentioning

confidence: 99%

“…The presence of a high temperature part to the system suggests porphyry-related gold potential at depth (e.g., Yilmaz et al 2010). However, the advanced-argillic assemblage overprinting near-neutral alteration minerals of the mineralization system formed at temperatures below 250°C, based on the presence of kaolinite and alunite association (e.g., Brown 1978;Henley and Ellis 1983;Reyes 1990;White and Hedenquist 1995;Yilmaz et al 2007Yilmaz et al , 2010.…”

Section: Discussionmentioning

confidence: 99%

See 3 more Smart Citations

Geological setting and timing of the Chah Zard breccia-hosted epithermal gold–silver deposit in the Tethyan belt of Iran

et al. 2011

View full text Add to dashboard Cite

The breccia-hosted epithermal gold-silver deposit of Chah Zard is located within a high-K, calc-alkaline andesitic to rhyolitic volcanic complex in the central part of the Urumieh-Dokhtar Magmatic Arc (UDMA), west central Iran. The total measured resource for Chah Zard is ∼2.5 million tonnes of ore at 12.7 g/t Ag and 1.7 g/t Au (28.6 t Ag, 3.8 t Au), making it one of the largest epithermal gold deposits in Iran. Magmatic and hydrothermal activity was associated with local extensional tectonics in a strike-slip regime formed in transtensional structures of the Dehshir-Baft strike-slip fault system. The host rocks of the volcanic complex consist of Eocene sedimentary and volcanic rocks covered by Miocene sedimentary rocks. LA-ICP-MS U-Pb zircon geochronology yields a mean age of 6.2±0.2 Ma for magmatic activity at Chah Zard. This age represents the maximum age of mineralization and may indicate a previously unrecognized mineralization event in the UDMA. Breccias and veins formed during and after the waning stages of explosive brecciation events due to shallow emplacement of rhyolite porphyry. Detailed systematic mapping leads to the recognition of three distinct breccia bodies: volcaniclastic breccia with a dominantly clastic matrix; gray polymict breccia with a greater proportion of hydrothermal cement; and mixed monomict to polymict breccia with clay matrix. The polymictic breccias generated bulk-mineable ore, whereas the volcaniclastic breccia is relatively impermeable and largely barren. Precious metals occur with sulfide and sulfosalt minerals as disseminations, as well as in the veins and breccia cements. There is a progression from pyrite-dominated (stage 1) to pyrite-base metal sulfide and sulfosalt-dominated (stages 2 and 3) to base metal sulfide-dominated (stage 4) breccias and veins. Hydrothermal alteration and deposition of gangue minerals progressed from illite-quartz to quartz-adularia, carbonate, and finally gypsum-dominated assemblages. Free gold occurs in stages 2 and 4, principally intergrown with pyrite, quartz, chalcopyrite, galena, sphalerite, and Ag-rich tennantite-tetrahedrite, and also as inclusions in pyrite. High Rb/Sr ratios in ore-grade zones are closely related to sericite and adularia alteration. Positive correlations of Au and Ag with Cu, As, Pb, Zn, Sb, and Cd in epithermal veins and breccias suggest that all these elements are related to the same mineralization event.

show abstract

Section: Geochemistry Of Hydrothermal Alterationsupporting

confidence: 62%

Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

Geological setting and timing of the Chah Zard breccia-hosted epithermal gold–silver deposit in the Tethyan belt of Iran

et al. 2011

View full text Add to dashboard Cite

show abstract

“…The deposits of Tesbihdere, Azitepe and Basmakci have characteristics in common with many other epithermal deposits in western Turkey, such as Kartaldag and Madendag [16], Bergama [41], Koru [6,7] and a compilation of deposits by [42]. Of direct relevance to this study is the work of [15] on the Sahlinli (their regional name which includes the mineralization at Azitepe, Basmakci and Ulu Dere) and Tesbihdere deposits with which we can compare our data.…”

Section: P-t Conditions Of Mineralizationmentioning

confidence: 94%

Fluid processes in the Tesbihdere base-metal-Au deposit: Implications for epithermal mineralization in the Biga Peninsula, NW Turkey

et al. 2014

View full text Add to dashboard Cite

Abstract:Tesbihdere is one of a number of spatially close epithermal Cu-Pb-Zn-Ag-Au deposits hosted by andesites and rhyolites, typical of deposits in the Biga peninsula. Microthermometry of fluid inclusions shows a wide range of temperatures, ∼360-170 • C, and salinities, ∼10-0.5 wt.% NaCl, in the different deposits studied. Dilution of a moderately saline magmatic? fluid with meteoric water occurred at constant temperature indicating, the temperature of both fluids was controlled by the geological environment. Boiling was not a major factor, but did occur in very minor amounts. The large range of temperatures within individual samples can only reasonably be explained by variations from near lithostatic to hydrostatic pressure during vein and fracture opening. That this pressure decrease did not produce extensive boiling suggests that vein opening was gradual rather than aggressive, allowing the pressure and temperature decrease to follow a path close to the L-V boiling curve. P-T reconstruction places emplacement of these ore veins at between 300-500 m beneath the surface. Similarities of LA-ICPMS of fluid inclusions from Tesbihdere, Azitepe and Basmakci, supports the conclusion that they were part of the same contemporaneous mineralizing system. The fluids are dominated by Na, with the concentrations of K>Ca>Mg combined equivalent to the concentration of Na. The range of K/Na ratios is not consistent with the fluid inclusion temperatures as the calculated temperatures are significantly higher indicating the fluids were not close to equilibrium with the enclosing rocks.

show abstract

Porphyry Systems; Fossil and Active Epithermal Systems

Pirajno

2009

Hydrothermal Processes and Mineral Systems

View full text Add to dashboard Cite

Low-sulfidation type Au–Ag mineralization at Bergama, Izmir, Turkey

Cited by 57 publications

References 46 publications

Geological setting and timing of the Chah Zard breccia-hosted epithermal gold–silver deposit in the Tethyan belt of Iran

Geological setting and timing of the Chah Zard breccia-hosted epithermal gold–silver deposit in the Tethyan belt of Iran

Fluid processes in the Tesbihdere base-metal-Au deposit: Implications for epithermal mineralization in the Biga Peninsula, NW Turkey

Porphyry Systems; Fossil and Active Epithermal Systems

Contact Info

Product

Resources

About