Original Research Paper
Exploration and Mining
Amir Salimi; Samaneh Barak; Mahyar Yousefi
Abstract
An accurate threshold value makes a precise geochemical separation into anomaly and background areas. The threshold assignment using structural methods are preferred to non-structural methods. In this research, the U-spatial statistics, a structural based method, was used to study soil type geochemical ...
Read More
An accurate threshold value makes a precise geochemical separation into anomaly and background areas. The threshold assignment using structural methods are preferred to non-structural methods. In this research, the U-spatial statistics, a structural based method, was used to study soil type geochemical data of the Neysian region. The optimal U-values obtained by this method for each sample were successfully utilized to separate the abnormal and background samples, accurately. In addition, based on the optimal distance of each sample, the abnormal samples identified in the previous step were classified in terms of geochemical intensity into strong, medium and weak samples. The goodness of U-spatial statistics performance in identifying abnormal areas were validated using drilled boreholes in the area. The U-spatial statistics not only succeeded in correctly identifying anomalous samples, but it also correctly identified some samples as the background whiles they had been recognized as anomaly by a non-structural method. All results obtained were validated by the several drilled boreholes.
Original Research Paper
Economic Geology
Mehdi Moradi; Ebrahim Tale Fazel
Abstract
Mouchesh gold deposit (0.7 Mt @ 1.3 g/t gold) is located in the Takab-Delijan gold belt. Mineralization with several 28 gold-bearing quartz-sulfide veins (N40E-trending, 1 to 10 m wide, and 5 to 200 m long) has been formed in the host of Lower Cretaceous andesite and andesitic lithic tuff units. Open ...
Read More
Mouchesh gold deposit (0.7 Mt @ 1.3 g/t gold) is located in the Takab-Delijan gold belt. Mineralization with several 28 gold-bearing quartz-sulfide veins (N40E-trending, 1 to 10 m wide, and 5 to 200 m long) has been formed in the host of Lower Cretaceous andesite and andesitic lithic tuff units. Open space-filling, comb, and disseminated textures are important mineralization textures that were formed in quartz-sulfide±gold veins (vein I) and quartz-barite-galena (vein II), which and cut later by carbonate veins (vein III). The homogenization temperature (Th) and salinity of the fluid inclusions, respectively, with an average temperature of 180 °C and salinity of 0.2 wt% NaCl eq. (vein I), 155 °C and 1.6 wt% NaCl eq. (vein II), and 135 °C and 1.5 wt% NaCl eq. (vein III). The values of δ34S in sulfide minerals of veins I and II are between +0.1 to ‒3‰ (δ34SH2S between ‒0.3 to +0.4‰), which indicates a single magmatic source for sulfur. The results of this research reveal that the existence of hydrostatic conditions (e.g., boiling) in the Mouchesh deposit has caused H2S releasing from the hydrothermal fluid, the decrease in the solubility of the bisulfide complex Au(HS)‒2, and ultimately the gold instability.
Original Research Paper
Economic Geology
Pooya Seyed Salehi Naeini; Saeid alirezaei
Abstract
The Kharestan-Bidester area, northwest of the Taftan volcano, is covered by a series of Plio-Quaternary lava flows and pyroclastic materials. The area is marked by extensive silicic and argillic alterations. The silicic zones, distinguished by vuggy texture, are bordered by advanced-intermediate argillic ...
Read More
The Kharestan-Bidester area, northwest of the Taftan volcano, is covered by a series of Plio-Quaternary lava flows and pyroclastic materials. The area is marked by extensive silicic and argillic alterations. The silicic zones, distinguished by vuggy texture, are bordered by advanced-intermediate argillic alterations. They occur as linear features across faults and fractures, as well as massive bodies of variable sizes, and are comparable, at regional scale, to lithocaps developed in the upper parts of the porphyry systems. The silicic-argillic zones are mineralized with gold at variable grades. Gold occurs mostly as submicroscopic particles of electrum and native gold. Pyrite, variably oxidized at surface and shallow levels, is the main metallic mineral, associated with trace sulfosalts, tetrahedrite and enargite. Minor malachite staining locally occurs in the ore zones. The geologic setting, hydrothermal alteration, ore mineralogy and texture/structure allow the Kharestan-Bidester to be compared with high-sulfidation epithermal systems.
Original Research Paper
Petrology
Seyevahid Shahrokhi
Abstract
The Dalayon granitoid is located in the south of Borujerd and, is part of the Sanandaj-Sirjan zone. The lithological composition includes granodiorite, granite, pegmatite-granite, tonalite, quartz diorite, tourmaline-bearing pegmatite, and quartz-tourmaline veins intruded into volcanic and metamorphic ...
Read More
The Dalayon granitoid is located in the south of Borujerd and, is part of the Sanandaj-Sirjan zone. The lithological composition includes granodiorite, granite, pegmatite-granite, tonalite, quartz diorite, tourmaline-bearing pegmatite, and quartz-tourmaline veins intruded into volcanic and metamorphic rocks. The minerals set of granodiorite mass with color leucocratic to mesocratic index mainly minerals quartz, plagioclase, orthose and microcline and secondary minerals biotite, muscovite, zircon, garnet, apatite, rutile, leucoxene, and sphene. The indicator mineral of ferromagnesian in these rocks is biotite, which has a primary nature rich in magnesium and poor in chlorine in composition. The value of Fe/Fe+Mg ratio shows an average 0.44(apfu), that indicates that the studied micas are placed in the range of biotite and between siderophiles and anite poles. The average crystallization temperature of biotites is 681ºC and the average formation pressure is 2.95kb based on the total aluminum of biotites, which indicates formation at a shallow depth. Based on the proportions of MgO- FeO-Al2O3 in biotites, the magma that produced this mineral is of the calc-alkaline type. The existence of relatively high fugacity of oxygen and oxidant environment indicates magma of mantle-crust origin and host rock of magnetite granitoid series and I-type granitic rock for biotites.
Original Research Paper
Geological Environment and Engineering
razieh Lak; Ali Mohammadi; Javad Darvishikhatooni; Elnaz Aghaali
Abstract
Heavy rain falls in dray seasons with extreme water flow is one of the important factors in very intense damage urban areas and agricultural lands of the of arid and semi-arid plateaus and highlands. In semi-arid area such as southern flank of Alborz Mountain, neglecting the effect of geomorphologic ...
Read More
Heavy rain falls in dray seasons with extreme water flow is one of the important factors in very intense damage urban areas and agricultural lands of the of arid and semi-arid plateaus and highlands. In semi-arid area such as southern flank of Alborz Mountain, neglecting the effect of geomorphologic features, (e.g. river truck channel depth, slope, sinuosity, river flood plain width and slope), illegal construction on the river legal boundary, as well as the effect of present-day climate change (change in annual rainfall precipitation and patterns, especially in El Niño conditions), cause environmental hazards such as extreme floods in urban areas. Imamzadeh Davood village is a religious-tourist place in the central the Alborz In this research, we investigated the 28th July, 2022 Imamzadeh Davood flood controlling factors and its effect on low-stream village (Imamzadeh Davood) and provided scientific solutions to decrees and prevent the destructive effect of future potential floods. The unusual extreme flood occurred after heavy and sudden rain in July (usually the area receives almost 0 cm of precipitation), causing a large volume of high-density mud flow with highly destructive power in the upper catchment.
Original Research Paper
Stratigraphy and Palaeontology
JAVAD SAADATNEJAD
Abstract
Kalariz formation beds in Javaherdeh area has well exposure for plant macrofossils study. The studied area is located at the northern Alborz structural-facies zone, The Kalariz formation in Javaherdeh section consists of shale, siltstone, sandstone and conglomerate beds with coal veins and intrusive ...
Read More
Kalariz formation beds in Javaherdeh area has well exposure for plant macrofossils study. The studied area is located at the northern Alborz structural-facies zone, The Kalariz formation in Javaherdeh section consists of shale, siltstone, sandstone and conglomerate beds with coal veins and intrusive beds. It lies conformably, with a coarse grain sandstone bed, on top of the Laleband formation . Its upper contact is unconformable and sharp under the conglomerate beds of Javaherdeh formation. In this study 29 species of plant macrofossils from 13 genera were studied and introduced, including orders of Equisetales, Osmundales, Filicales, Cycadales, Bennettitales, Ginkgoales and Coniferales and an unknown reproductive organ. On the basis of the occurrence of index fossils such as Cladophlebis nebbensis, Nilssonia brevis, Dictyozamites asseretoi, Taeniopteris reversa, Taeniopteris tenuinervis and Baiera muensteriana Rhaetian age, and based on the occurrence of index taxa such as Dictyophyllum exile, Pterophyllum aequale and Pterophyllum bavieri, Late Rhaetian age is proposed for this assemblage. In this study, Ginkgoites whitbiensis from Iran and Taeniopteris reversa from Alborz are recorded for the first time. Clathropteris elegans, Nilssonia harrisi, Ginkgoites parasingularis and Ginkgoites lepida are recorded for the first time from Late Triassic beds of Iran
Original Research Paper
Tectonics
Babak Samani
Abstract
The use of spatial orientation of structural elements provides a great help to understand the geometry of shear zones. Investigating the indices of non-axial deformable flow in two areas of shape preferred orientation (SPO) and lattice preferred orientation (LPO) of quartz in the deformed rocks of Koli ...
Read More
The use of spatial orientation of structural elements provides a great help to understand the geometry of shear zones. Investigating the indices of non-axial deformable flow in two areas of shape preferred orientation (SPO) and lattice preferred orientation (LPO) of quartz in the deformed rocks of Koli Kosh complex in the Sanandaj-Sirjan metamorphic belt at the north of Fars province show the dextral shear component. Quartz c-axis preferred orientation indicates the dominance of bulging and sub-grain rotation recrystallization in the thermal range of 379±50 to 448±50 degrees Celsius and pressure of 3 to 3.5 kbar. According to stereography projection of pole of foliation and lineation the plane of vorticity normal section was estimated as N15W/45SW. Assuming the compatibility of the north and south thrust systems with the boundary of the shear zones, the rake angle of the boundary of the shear zone and the vorticity normal section was calculated equal to 19 degrees. Therefore, it is possible to consider the oblique transpiration model with triclinic geometry as the structural evolution model of this shear zone.
Original Research Paper
Petroleum geology
Fatemeh Taghizadeh; Khaled Maroufi; Reza Falahat; Ali Opera
Abstract
Objective of this study is to conduct a geochemical assessment over source candidates in the Garangan oilfield using Rock-Eval pyrolysis and vitrinite reflectance to identify factors contributing to the lack of hydrocarbon reserves in the Middle Cretaceous – Early Oligocene petroleum system. Furthermore, ...
Read More
Objective of this study is to conduct a geochemical assessment over source candidates in the Garangan oilfield using Rock-Eval pyrolysis and vitrinite reflectance to identify factors contributing to the lack of hydrocarbon reserves in the Middle Cretaceous – Early Oligocene petroleum system. Furthermore, the impact of mineral matrix retention, inert organic material (OM) and maturity were examined, and the results were used to split TOC and S2 parameters into the oil-prone and gas-prone components. Based on results, Pabdeh formation is an immature rich source, exhibiting the highest levels of active OM. Unexpectedly, OM quantity for the Kazhdumi source rocks is fair, for which contribution from inert OM is substantial. Significant inert OM is also confirmed for the oil/gas-prone upper Dariyan shales and gas-prone Gadvan samples. These characteristics seem to be related to the activities of the Khark-Mish paleo-high during the Cretaceous. Moreover, the Cretaceous intervals show a maturity level equivalent to the preliminary stages of main oil generation phase. Finally, owing to the presence of high-quality reservoir and cap strata, the absence of economical reserves in the Asmari and Bangestan reservoirs of the oilfield is possibly related to mediocre OM quantity and quality, and insufficient maturity of the source candidates.
