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Volume 19, Issue 1 (4-2011)
Abstract
The study area is located about 45 km of southwest Neyshabour and east of Arghash village. Both intrusive and volcanic rocks are exposed in the study area and they are intensively altered due to hydrothermal fluid. The alteration zoning in the study area consists of potassic, sericitic, carbonatization, silicification and propylitic. More than 10 intrusive rocks with composition in the range of monzonite to diorite are identifined. Chemically, they are met-aluminous and calc-alkaline. Based on mineralogy and high values of magnetic susceptibility, granitoid rocks of the area are belonging to ilmenite-series and I-type. Both disseminated and vein type mineralization is rcognized. Pyrite is the dominante sulfide. Stream sediment and rock chip geochemical exploration carried out in the area. Highest Cu anomaly (Cu = 108 ppm) is associated with quartz hornblend diorite porphyry. Based on alteration, type of intrusive rocks and geochemical anomalies, Arghash area has potential for Cu- porphyry mineralized system.
Almasi, Nabatian, Mahdavi, Li,
Volume 29, Issue 4 (12-2021)
Abstract
Oxygen fugacity (fO2) and zircon crystallization temperatures (Ti-in-zircon) of ore-bearing quartz monzonite intrusive rocks of ChahShaljami and Dehsalam Cu-Mo porphyry deposits were measured by using calculations of zircon trace element values and oxidation conditions of parental magma were investigated. The Ce4+/Ce3+ values for ChahShaljami and Dehsalam are in a range of 8 to 295 with an average of 125 and 3 to 171 with an average of 35, respectively, therefore they were not in the favorable range for porphyry mineralization. The estimated fO2 values for ChahShaljami and Dehsalam are in the range of ∆FMQ -1.8 to MFMQ +0.6 with an average of ∆FMQ -0.6 and ∆FMQ -1.3 to ∆FMQ -0.4 with an average of ∆FMQ -0.8 which is at least ∆FMQ +1 less than the values of porphyry copper mineralization in the world.. Based on the zircon log fO2 values of ore-bearing intrusive rock, the parental magma originated from partial melting of supra-subduction mantle peridotite zone within oceanic slab. Melting under unfavorable conditions (under magnetite-hematite (HM) buffer and in faylite-magnetite-quartz (FMQ) buffer condition, and lack of sufficient Cu and sulfur at the source), which is supported by evidences in deposit such as lack of magnetite-hematite intergrowths, was not ideal for porphyry Cu porphyry mineralization in the two regions. The results are supported also by previous whole-rock major and trace element geochemistry and Sr-Nd isotopic values.