Economic Geology
Sholeh Malekshahi; Masoumeh Khalajmasoumi; Hadi Mohammad- Doost; Mona Sojdehee; Shahrzad Aboutorab
Abstract
The Sarkuh Porphyry Copper deposit is located about 6 km southwest of Sarcheshmeh porphyry copper deposit. Alterations in the region include advanced potassic, propylitic, phyllic and argillic. Copper mineralization is mainly associated with porphyry granodiorite mass. Minerals include chalcopyrite, ...
Read More
The Sarkuh Porphyry Copper deposit is located about 6 km southwest of Sarcheshmeh porphyry copper deposit. Alterations in the region include advanced potassic, propylitic, phyllic and argillic. Copper mineralization is mainly associated with porphyry granodiorite mass. Minerals include chalcopyrite, pyrite, magnetite and some molybdenite. Fluid inclusion studies were performed on quartz from the sulfide viens of the potassic fraction and showed that the main mineralization phase was present with a homogenization temperature between 250 and 527 ° C, salinity between 13.6 and 52.9 wt٪ NaCl, has a high salinity in Sarkuh deposit (Orthomagmatic phase and hypogene mineralization). The homogenization temperature in the late stages of the receding phase (convective phase and the influence of atmospheric waters in the hydrothermal cycle) is around 132 to 165 degrees Celsius and its salinity is 0.005 to 4.74% equivalent to the weight of NaCl. The observed salinity variation can be attributed to the boiling event. The investigation of sulfur isotope composition on pyrite and chalcopyrite minerals in Sarkoh deposit was between +1 and 2.7‰, which indicates the magmatic source of sulfur. The stable oxygen isotope data on quartz veins, show positive range between 7.6 to +9.3‰ with an average of +8.5, indicates a magmatic source for hydrothermal fluids. Also, due to the limited range of sulfur isotopic composition, it can be concluded that the isotopic composition of sulfur has not undergone changes or contamination by other sources of sulfur, or the mixing of magmatic fluid with other sources has been very insignificant. Isotopic thermometry shows the temperature of 315°C and 476°C for the pair of pyrite-chalcopyrite minerals.
M. R. Hosseini; S. Alirezaei; J. Hassanzadeh
Abstract
The Bahr Aseman volcanic-plutonic complex is located to the southeast of the Kerman magmatic belt. Unlike Kerman magmatic belt which formed and evolved during Cenozoic in a dominantly continental arc and post-collision tectonic setting, Bahr Aseman complex formed during Late Cretaceous in an oceanic ...
Read More
The Bahr Aseman volcanic-plutonic complex is located to the southeast of the Kerman magmatic belt. Unlike Kerman magmatic belt which formed and evolved during Cenozoic in a dominantly continental arc and post-collision tectonic setting, Bahr Aseman complex formed during Late Cretaceous in an oceanic island-arc setting. The complex is composed of andesitic and andesitic-basaltic lava flows and subordinate pyroclastic materials and carbonate interlayers, as well as abyssal tonalite to quartz-diorite and quartz- monzodiorite intrusive bodies and shallow dioritic intrusions. Vein- type copper deposits, iron skarn and copper skarn are the main ore deposit types in Bahr Aseman. Chalcopyrite is the main ore mineral in vein-type and skarn-type copper deposits; the mineral is converted to oxide copper ores at surface and shallow depths. Magnetite is the main commodity in skarn type iron deposit. Highly altered porphyritic bodies associated with copper oxide ore were identified that are comparable, in some aspects, with porphyry type copper deposits; subsurface data, however, is required for conclusive remarks. The various types of deposits are distinguished by distinct fluid inclusion characteristics. In the vein type copper deposits, fluids in association with mineralization represent dominant homogenization temperature (Th) of 150-220 ºC and salinity of 5-10 and 25-30 wt% NaCl. Fluids in the skarn type copper deposits represent 170-250 ºC and ranges of 5-15 and 27-35 wt% NaCl as dominant Th and salinity, respectively. The δ34S values in the vein-type copper deposits vary between +3.9 and +5‰, suggesting a magmatic origin for sulfur and probably metals (directly derived from magma or leached from magmatic rocks). Sulfur isotope ratios for two samples from Moka are +4.3 and +7.1‰, slightly different from typical magmatic δ34S ranges. Oxygen and hydrogen isotope ratios for the vein-type copper deposits, measured on quartz and fluids extracted from inclusions in the mineral, are -6.6 to +1.9‰ and -79.4 to -51.8‰, respectively. This values suggest mixing of magmatic and meteoric fluids and/or fluid-rock interactions at different ratios. It appears that larger deposits have more shares of fluids with magmatic origin. With regards to the island-arc tectonic setting, recognized deposit types and ore minerals paragenesis, finding new copper and iron and probably gold deposits are possible in the Bahr Aseman area.
A Mohebi; A Hezarkhani; M Behzadi; H Mirnejad; H Taghi Zadeh
Abstract
Bondar Hanza porphyry copper deposit occurs 150 km southeast of Kerman, in southern part of the Urmia-Dokhtar zone and in Dehaj-Sardoiyeh zone. This ore deposit has formed in diorite to granodiorite rocks. The present paper deals with the study of fluid inclusion on quartz and hornblende samples as well ...
Read More
Bondar Hanza porphyry copper deposit occurs 150 km southeast of Kerman, in southern part of the Urmia-Dokhtar zone and in Dehaj-Sardoiyeh zone. This ore deposit has formed in diorite to granodiorite rocks. The present paper deals with the study of fluid inclusion on quartz and hornblende samples as well as the measurement of isotopic ratio of oxygen and hydrogen with the aim to recognize characterization of hydrothermal fluids effective in mineralization. The studied veinlets are divided into five groups. Veinlet I: fluid of high pressure (>300 MPa) and medium to high temperature (250°C-300°C) with salinity of 38-45 Wt%NaCl that includes molybdenum mineralization. This veinlet contains halite and anhydrite and has resulted in potassic and sodic-calcic mineralization in deeper parts of the ore deposit. Veinlet II: high pressure (>300 MPa), high salinity (33-47 Wt%NaCl) and high temperature (250°C-420°C), containing copper and molybdenum mineralization as well as potassic alteration. Veinlet III: high salinity (40-56 Wt%NaCl), high pressure (>300 MPa) and high temperature (200°C-500°C), containing copper mineralization. Veinlet IV: medium to low salinity (6-7 Wt%NaCl), medium temperature (approximately 170°C), low pressure (0/7-0/8 MPa), containing no mineralization. The study performed indicate that the boiling occurred in the initial magma, as a result of pressure and temperature changes and mixing with meteoric waters, caused copper and molybdenum mineralization. Results obtained from oxygen and hydrogen isotopic analysis in quartz show δ18O to vary from 3.9 to 6.3 per mil. Considering its formation temperature and based on thermometric study (130-400°C), the amount of δ18o in mineralizing fluid is from 5.26 to 6.19 per mil, being indicative of magmatic origin of mineralization fluids like the other porphyry copper deposits of Iran and the world. While results of hydrogen analysis existed in fluid inclusions of quartz mineral illustrate a range between -88 to -90 per mil, being indicative of a decrease in the amount of mineralizing fluid deuterium. These values are traceable to the effect of meteoric waters, given the propylithic and sodic alterations accompanied with potassic alteration in mentioned veinlet.
H Alizadeh; M Aryan; M Lotfi; M Ghorashi; M Ghorbani
Abstract
The Dehaj-Sardoiyeh Belt, which is a part of the Urmia-Dokhtar Volcanic-Plutonic Zone, consists of several economic porphyry copper deposits. This area is located on the right lateral shear zone surrounded by the Rafsanjan fault in the north and the Shahr-e Babak fault in the south. In this research, ...
Read More
The Dehaj-Sardoiyeh Belt, which is a part of the Urmia-Dokhtar Volcanic-Plutonic Zone, consists of several economic porphyry copper deposits. This area is located on the right lateral shear zone surrounded by the Rafsanjan fault in the north and the Shahr-e Babak fault in the south. In this research, spatial relationship among sixteen porphyry copper deposits, faults and fractures was studied. The results show a strong relationship between the Photo lineament factor and location of the porphyry copper deposits. The direction of lineament factor (d/D) was found to be highly correlated with the location of porphyry deposits. The results can be used in exploring preliminary porphyry deposits with regard to the geometry and mechanisms of the faults and fractures.
S Alaei Moghadam; M Karimi; M Mesgari; N Saheb Zamani
Abstract
Due to the extensive areas of potential mineral reserves in the country, it seems necessary to have a systematic approach to identify and convert indices of mineral deposits into mines. Existing various conceptual models of mineral deposits, variety of both quantitative and qualitative data to explore ...
Read More
Due to the extensive areas of potential mineral reserves in the country, it seems necessary to have a systematic approach to identify and convert indices of mineral deposits into mines. Existing various conceptual models of mineral deposits, variety of both quantitative and qualitative data to explore mineral deposits and the expertise and different interests, cause the mineral potential mapping process to be very complicated. So far, various methods such as the overlap index, fuzzy logic, neural networks and weights of evidence are used for modeling this complexity. Consideration the fuzzy nature of mineral exploration in the process of modeling exploratory data, applying expert knowledge and flexibility for all types of mineral deposits in the form of an integrated system is essential. Compared with other methods fuzzy inference system has stated characteristics. To verify this, in this study, a fuzzy inference system for modeling mineral potential was proposed and for the Chah Firoozeh copper deposit was implemented. The main stages of this research include fuzzifying factor maps using the appropriate membership functions and linguistic variables, combining factor maps using fuzzy inference (by creating if_then fuzzy rules database and using an appropriate decision-making model) and generating mineral potential map with defuzzification output.
In the resulted mineral potential map, porphyry copper mineralization prone area is located in the central regions with north-south extension. For evaluation, 24 exploration boreholes in the area are complying with the mineral potential map. Based on the four classification types of mineral potential map, the compliance rate was calculated as 63.64%, 75%, 63.95% and 80.23%. Obtained mineral potential map is more accurate in the very low potential areas and 81.52% of the holes with very low state are located properly. In addition, resulted mineral potential map was compared with the mineral potential map generated using only fuzzy operators and without fuzzifying factor maps. The comparison shows that the mineral potential map that was generated using fuzzy inference system, in four classifications used in this study has 6% greater compliance with the exploration boreholes in average.
