More than 50 doubly polished sections of 0.3- to 0.5-mm thick were prepared from the various kinds of vein-veinlets formed in the early to middle stages of mineralization and hydrothermal alteration of the diorite to granodiorite porphyries host rocks samples, which were collected from drill holes and outcrops at the Haftcheshmeh PCD.
Fluid inclusion petrography was examined with the Keyence VHX-1000 digital microscope (2x-200x, 100x-1000x, 500x-5000x) for obtaining the High-resolution mapping of doubly polished sections and finding the exact location of the fluid inclusions in quartz veins; and Zeiss AxioImager A1m optical microscope for petrographical observation and phase transition in the room temperature at the microanalysis Laboratory of the Geo-Resources, Nancy, France.
After detailed petrographical studies; over 300 suitable fluid inclusions in the 15 wafers (100-150 ?m thick) ranging from less than >5 to ~20 ?m in diameter in size were selected as contemporaneous precipitation (Wilkinson, 2001) of the quartz-sulfide veinlets located in the euhedral to subhedral quartz crystals.
The barren quartz-Kfeldspar ± biotite –pyrite veinlets in stage II, the quartz–molybdenite±pyrite veinlets in stage III, the quartz–polymetallic sulfide veinlets in stage IV within the hypogene alteration zones (the potassic and sericitic alteration zones) were chosen for fluid inclusions (FIs) microthermometry and Raman spectroscopy.
Petrographical studies suggested that the studied quartz crystals belonging to the early to middle stages veinlets of the Haftcheshmeh PCD are (FIs)-rich with medium size ranging from 7 to 15 which were appropriated for freezing and heating stages of microthermometry analysis. However, we have found that majority of the (FIs) belong to the pre-ore stage I veinlets were too small >5 and therefore the freezing stage on them was indistinguishable.
The fluid inclusions first were mapped photographically to record their locations. Then, the smaller chips were cut from the slides and transferred to a Linkam THMS600 heating-cooling stage, attached to an Olympus BX51 microscope equipped with 20X, 50X and 100X objectives and a monitoring video apparatus in the fluid inclusions laboratory of GeoRessources at Université de Lorraine (Vandoeuvre-lès-Nancy, France). The stage was regularly calibrated over a range of temperatures by using the synthetic fluid inclusions from quartz samples of two Alpine veins (Planggenstock and Grimsel Pass) of the Aar Massif (Central Alps, Switzerland) and calculating the following phase transitions: the triple point of CO2 at -56.6 C, the triple point of H2O at 0.0 C and the critical point of H2O at 374± 1.0 C.
The temperatures of the flowing parameters: Te, the eutectic temperature of the aqueous phase; Tm(ice) the final melting temperature of ice. Tm(HH), final melting temperature of hydrohalite; Tm(Clath), final melting of the carbonic phase; TeCO2, the triple point temperature of the carbonic phase (?56.6?C for pure CO2); ThCO2, carbonic phase homogenization; Th(LorV): the bulk homogenization temperature (LV to liquid or VL to vapor respectively); TdBubble: disappearance of the vapor bubble phase. Tdd: the disappearance of the daughter minerals; were generally measured at ?0.1°C/min for freezing stage and ?1 to 5 °C/min for the heating stage, but reduced to ?0.2 °C/min close to the phase transformation temperatures.
The salinities of NaCl–H2O fluid inclusions; expressed as wt.% NaCl equiv; were calculated using the final ice melting temperatures in the equations provided by Bodnar (1993).
The salinities of CO2-bearing fluid inclusions with or without clathrates formation upon cooling were calculated using the final melting temperatures of CO2-clathrate after Collins, 1979 and using the technique of Hedenquist and Henley, 1985; respectively.
Several types of daughter minerals, opaque minerals and accidentally captured crystals including halite, sylvite, hematite, chalcopyrite, and unidentified types were distinguished by petrography. Because halite and sylvite are the most types of daughter minerals in the FIs and also because of the non-melting feature of the opaque daughter minerals upon heating stage; we estimated the dissolution temperature of halite and sylvite daughter minerals as Tdd. The salinities of halite-daughter mineral-bearing fluid inclusions that homogenize by halite dissolution; Tdd, were calculated by using the data of Bodnar and Vityk (1994) and the salinities of halite-daughter mineral-bearing fluid inclusions that homogenize by bubble dissolution; TdBubble were calculated based on the method of Lecumberri-Sanchez et al. (2012)