Intermediate sulfidation epithermal gold-base metal deposits in Tertiary subaerial volcanic rocks, Sahinli/Tespih Dere (Lapseki/Western Turkey)

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

“…This data agrees with the fluid inclusions results from the nearby deposit of Koru [6] that [15] claimed were in error, because they did not observe low eutectic values, instead measuring higher eutectic temperatures of ∼ −28…”

“…However, the change from lithostatic to hydrostatic pressure on opening of the veins is sufficient to produce the wide range of homogenization temperatures due to loss of heat from the fluid by adiabatic expansion. Based on our P-T calculations we can show the veins at Tesbihdere and Azitepe were emplaced about 500 m beneath the surface and at Basmakci about 200-300 m and not at around 1000 m as [15] suggest.…”

“…The veins are acting as regions of heterogeneous fluid mixing between magmatic derived, higher salinity, fluid and meteoric water. This occurs over a very limited temperature range and there is no evidence of cooling caused by dilution as [15] propose. We suggest the transition from near lithostatic to hydrostatic pressure was gradual in the samples studied, so that boiling may not have been a significant occurrence, but we cannot rule out that evidence of more extensive boiling was lost in this shallow environment.…”

“…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. Their fluid inclusion study reports results for T , salinity with the range of values that are essentially identical to this study.…”

Illite occurrences related to volcanic-hosted hydrothermal mineralization in the Biga Peninsula, NW Turkey: Implications for the age and origin of fluids

“…Tesbihdere but not the Ovacik-Narlica deposits (Yilmaz et al, 2007(Yilmaz et al, , 2010 That we have only two samples from the areas that would have seen the highest temperature magmatic fluids, it is not surprising we find only one generation of illite. It may be possible that different generations of illites were formed away from the main upwelling zone by cooler fluids with a resultant change in D and  18 O in line with the predicted isotopic fractionation at lower temperatures.…”