B Mehrabi; M Ghasemi Siani; E Tale Fazel
Abstract
The Torud-Chah Shirin volcanic-intrusive arc, in the south of Kavir-e-Chah Jam depression (SW of Damghan), hosted many Pb, Zn, Cu, Ag and Au occurrences and deposits. Cheshmeh Hafez (Pb-Zn±Cu±Ag±Au) and Challu (Cu-Au±Ag) polymetallic vein-type ore deposits are the major one ...
Read More
The Torud-Chah Shirin volcanic-intrusive arc, in the south of Kavir-e-Chah Jam depression (SW of Damghan), hosted many Pb, Zn, Cu, Ag and Au occurrences and deposits. Cheshmeh Hafez (Pb-Zn±Cu±Ag±Au) and Challu (Cu-Au±Ag) polymetallic vein-type ore deposits are the major one located in the central part. The Tertiary calc-alkaline volcanism and related mineralization occurred along the main Anjillo fault in the north and the Torud fault in the south with NW-SE trend. The exposed rocks in the Torud-Chah Shirin consist of volcaniclastic sequence composed of siltstone, thin bedded sandstone, lapilli tuff and volcano breccias and mostly andesitic and andesitic-basalt flows. Main host rocks at Cheshmeh Hafez are andesite and andesitic-basalt, while in Challu are trachy-andesite and basaltic trachyandesite, hosted polymetal hydrothermal mineralization in the area. Mineralization in the Cheshmeh Hafez occurred in three main stage includes stage 1) vein and disseminated pyrite and chalcopyrite hosted in quartz with homogenization temperature of 188 to 238°C and salinity of 6 to 14 wt.% NaCl equiv, stage 2) main sulfide mineralization with vein, disseminated and brecciate texture hosted in quartz with homogenization temperature of 243 to 276°C and salinity of 11 to 18 wt.% NaCl equiv and stage 3) replacement mineralization and vein-type (quartz and barren calcite) with homogenization temperature of 148 to 185°C and salinity of 4 to 11 wt.% NaCl equiv. Mineralization in the Challu district with low expanse and simple mineralogy occurred at two stage composed of stage 1) vein and veinlet pre-mineralization stage includes specularite, magnetite, chalcopyrite and pyrite (I) hosted in quartz with homogenization temperature of 332 to 356°C and salinity of 7 to 11 wt.% NaCl equiv and stage 2) brecciate and stock-work post-mineralization stage includes pyrite (II), bornite, tetrahedrite, vein-type calcite and chlorite with homogenization temperature of 290 to 322°C and salinity of 3 to 7 wt.% NaCl equiv. According to the recent studies, it can be inferred that with distance increasing from Challu district to Chesmeh Hafez mining area, homogenization temperatures (Th), salinity and depth of mineralization decreases gradually and mineralization at Challu and Cheshmeh Hafez districts have characteristics of an individual mineralization system that caused by mixing of hydrothermal fluid with meteoric water.
E. Tale Fazel; B. Mehrabi; A. Khakzad; R. Kianpour
Abstract
Sangan iron ore deposit is located in 308 km southeast of Mashhad and eastern structural zone of Iran. Due to the high grade, low P-content and high reserve, Sangan is regarded as one of the major iron ore deposits in Iran. The important anomalies in Sangan consist of east, central and west anomalies ...
Read More
Sangan iron ore deposit is located in 308 km southeast of Mashhad and eastern structural zone of Iran. Due to the high grade, low P-content and high reserve, Sangan is regarded as one of the major iron ore deposits in Iran. The important anomalies in Sangan consist of east, central and west anomalies that Dardvey deposit is a typical magnetite-rich skarn developed along the contact of Sarnowsar I-type granite Oligo-Miocene age with high magnesium carbonate of Upper Cretaceous, formed in central anomaly. Dardvey deposit comprises of exoskarn, endoskarn and ore zones. The endoskarn zone is limited while exoskarn is extensive zone and includes sub-zones of garnet skarn, garnet-pyroxene skarn and pyroxene skarn in intrusive body side and epidote skarn beyond the intrusive body. Field evidence, mineralogical and microthermometry studies show three zones including; 1) intrusion of granitoid bodies in ranges of 320 to 520°C and 1kb pressure, 2) skarn mineralization zone consists of prograde stage are developed within the temperature ranges from 310 to 490°C in average salinity of 33.6 (wt.% NaCl), in association with metasomatic mineralization during a retrograde stage, developed within temperature ranges from 190 to 310°C in average fluid salinity of 13.6 (wt.% NaCl) accompanied by magnetite ore and massive pyrite, chalcopyrite and pyrrhotite. The late mechanism, including quartz vein-type mineralization and barren veins occurrence, comprises of subhedral to anhedral pyrite, chalcopyrite and phologopite bearing veins that occurred in two substages from 360 to 440°C temperature and average salinity of 33.4 (wt.% NaCl) and from 235 to 320°C temperature and average salinity of 14.6 (wt.% NaCl) in the skarn zone and intrusive body. According to studies, it may be fluid mixing and ore fluid dilution mechanisms by implications of low-temperature and salinity meteoric water and also, chemical composition changes of ore fluid due to water-rock interaction was the possible mechanism for ore-metal deposition of magnetite in the skarn zones and formation of sulfide ore minerals in the hydrothermal quartz vein and veinlets in late stage of mineralization in the area.
H. Jamali; A. Yaghubpur; B. Mehrabi
Abstract
Miveh – Rud area is located 50 km north of Tabriz and 65 km west of Ahar at 36ْْ 33′ 02″to 38ْ, 34′ 52″ N and 46 ْْ 12′ 20″ to 46 ْْ 14′ 35″ E. The oldest rock unit in the area includes a thick sequence of Paleocene sedimentary rocks comprising ...
Read More
Miveh – Rud area is located 50 km north of Tabriz and 65 km west of Ahar at 36ْْ 33′ 02″to 38ْ, 34′ 52″ N and 46 ْْ 12′ 20″ to 46 ْْ 14′ 35″ E. The oldest rock unit in the area includes a thick sequence of Paleocene sedimentary rocks comprising of sandstone, shale, siltstone, marl and marly limestone that have been intruded by a porphyritic intrusive body and dykes of granodioritic to diabasic composition (probably Oligocene in age). The intrusive rocks resulted in the formation of hornfels, skarn and alteration in Paleocene rocks. All of the mentioned rock units are unconformably covered by Pliocene age trachyte, trachyandesite. Alteration of potassic, sericitic, argillic, propylithic and silicification types occurred in the subvolcanic and sedimentary rocks, while there is no observed alteration in the volcanic cover. Anomalies of Au, Ag, Sb, Cu, Bi, W and Mo detected by geochemical investigations are confirmed by field evidences.
The anomalies of Sb, Ag, Au and As are located in the northern part, while the Cu, Co, W and Mo anomalies are in the southern part of the area. The degree of the contact metamorphism decreases toward the north and the potassic alteration can be shown mostly in the southern part of the area. This may suggest uplift and erosion of the southern part compared to northern part of the studied area. Composite halos of As, Pb, Ag / Cu, W and Co confirm the results.The mineralization includes formation of skarn, epithermal and sheeted veins. The epithermal veins cut the skarn and other contact metamorphic rocks.
S. Orandi; A. Yaghubpur; M. Nakhaei; B. Mehrabi; H. Sahraei; M. Behrouz
Abstract
Sarcheshmeh Copper Mine, one of the well known porphyry copper deposits, is located in 55 km south of Rafsanjan, south-eastern Iran. Metalliferrous deposit mining, prepare proper conditions for oxidation of sulphide minerals and acid mine drainage will be produced easily by chemical reactions between ...
Read More
Sarcheshmeh Copper Mine, one of the well known porphyry copper deposits, is located in 55 km south of Rafsanjan, south-eastern Iran. Metalliferrous deposit mining, prepare proper conditions for oxidation of sulphide minerals and acid mine drainage will be produced easily by chemical reactions between metal sulphides and water, with the presence of air. Investigations on impact of waste dumps on producing acid mine drainage at Sarcheshmeh copper mine shows decreased pH up to 3-5.5 in acid drainages with the presence of some dissolved toxic and heavy metals higher than permitted standard limits (WHO). In such degraded water and improper environment for aquatic life, just some of microorganisms are able to survive. At Sarcheshmeh copper mine in some of acidic drainages which maintain high dissolved elements, an acid tolerant alga recognized. The genus of this filamentous green alga is Ulothrix and species is Ulothrix gigas without antimicrobial and antifungal properties. The alga is observed in the drainages with high dissolved solids (TDS≈1800mg/l). It seems pH values, type of dissolved elements and secondary minerals formed on the substrate, are important factors in distribution of Ulothrix. This research shows the most prolific and densely populated communities occur in effluent with the pH 3- 4.5. The colloidal conditions and presence of suspended Iron and Aluminium prevent growth or reproduction of them. Sampling and chemical analysis of algae show elevated absorption of heavy metals. Therefore the presence of this alga is a factor to remove heavy metals from acid mine drainage naturally and improve the water quality.
