فهرست مطالب

Earth Sciences - Volume:11 Issue:1, 2019
  • Volume:11 Issue:1, 2019
  • تاریخ انتشار: 1398/01/12
  • تعداد عناوین: 8
|
  • Ayanangshu Das, Jyotirmoy Mallik *, Krishanu Bandyopadhyay, Rais Alam Pages 1-13
    The analysis of Anisotropy of Magnetic Susceptibility (AMS) is a powerful and rapid technique to examine the preferred orientations of mineral (magnetic) fabrics and can indicate the nature of a magma transport (vertical or lateral). The relationship between magnetic fabric and geometry of a dyke swarm enables us to understand magma emplacement processes. Depending on the mutual relationship of magnetic fabric and individual dyke geometry, mode of magma transport is interpreted. The knowledge on the nature of magma transport combined with information on geometry, magmatic overpressure and geochemistry enable us to comment on dyke emplacement processes, the location of possible feeders, syn-emplacement and post-emplacement deformations and prevailing stress regime during emplacement. A number of dykes and dyke swarms have been emplaced into the Indian shield at different points in time. Their ages vary from the Mesoarchean to Tertiary. We present here a review of three case studies where AMS technique was applied to the samples collected from Indian dykes. Two case studies are on the Proterozoic dykes that intruded into the Dharwar craton and the third case study is on Mesozoic dykes that punctured the South Indian Granulite Terrain (SIGT). The dykes generally show “normal” anisotropy fabric to indicate vertical magma emplacement with few exceptions where lateral/inclined magma flow was suggested or the results were inconclusive. We present here a critical review on the interpretation of such “anomalous” fabrics and comment on further studies that can be carried out to extract more information from such results.
    Keywords: Anisotropy of Magnetic Susceptibility (AMS), Dyke, Fabric, Emplacement
  • Novruz Novruzov, Anar Valiyev, Aydin Bayramov, Sabuhi Mammadov *, Javid Ibrahimov, Aygul Ebdulrehimli Pages 14-29
    Mineralogy, gold mineralization and metal contents of the Gadir deposit have been investigated during current research in order to determine the geological conditions, temporal and spatial relationship with certain mineral assemblages and associations. The mineralogy of orebodies is mainly composed of pyrite, chalcopyrite, sphalerite, galena, petsite, native gold, electrum and subordinate molybdenite. Gold is hosted by pyrite and chalcopyrite minerals in fracture-filling textures and forms a thin dispersion condition. The native gold was observed in chalcopyrite, which is probably related to the second stage of ore deposition. The Gadir deposit can be classified to Au-Ag-Cu-Zn±Pb stockwork-type mineralization which is characteristic of low sulfidation epithermal deposit.
    Keywords: Hydrothermal alteration, Ore mineralogy, Gold mineralization, Low sulfidation epithermal deposit, Gadir
  • Rahman Ahmadi *, Behnam Sheykhi Pages 30-37
    In this paper, the recovery of vanadium from the secondary tail deposits of iron ore by salt roasting-alkaline leaching and solvent extraction has been investigated. To extract the vanadium, after the characterizations studies (XRF, SEM, and EPMA analyzes), preliminary leaching was performed using HCl to reduce lime. Subsequently, the solid that was gained from this stage was put in the oven for palletizing and salt roasting (sodium carbonate) at the temperature of 850°C. This sample was leached in the presence of sodium bicarbonate (NaHCO3), under certain conditions. Solvent extraction experiments were carried out on the solution of carbonated leaching under different conditions. According to SEM studies, the dominant are calcium, vanadium, and phosphorus in the sample. The percentage of Vanadium (V), according to EPMA results in the 20 selected points, was determined as 0.65%. XRF analysis showed that V2O5 and CaO contents of sample were 2.04% and 51.72%, respectively. Lime was reduced to 32.59% after initial leaching with HCl. The carbonate leaching resulted in a total recovery of 93.46% at 85 °C for 60 minutes and with 40 g /l of sodium bicarbonate. In addition, under the optimum conditions of pH=6, the ratio Vaq/Vorg=1 and the organic phase concentration of  0.5 M using the anionic Aliquat 336 extractant, Vanadium can be recovered effectively  (extraction efficiency=97%) from alkaline leaching solution in the form of decavanadate  or and the anions in the form of  or in one stage.
    Keywords: Vanadium, Alkaline leaching, Solvent extraction, Effective parameter
  • Sina Saber Mahani *, Marzieh Khalili Pages 38-46

    Earthquake is one of the most destructive natural phenomena which has human and financial losses. The existence of an efficient prediction system and early warning system will be useful for reducing effects of destroying earthquake. In this paper by applying three filters (Fourier, Wavelet and Difference Logarithmic Filter (LDF)) on soil temperature time-series, anomaly behavior before the major earthquakes was studied. Aforementioned methods were performed of the Bam (2003), and Zarand (2005) earthquakes in Iran. The results indicate thermal anomalies were detected before earthquake occurrence. Furthermore, the LDF filter detects thermal anomaly as well as the Fourier and Wavelet filters. For validation of the results, the soil temperature data of the Bam earthquake were considered from the Bam meteorological station and also from the Joroft meteorological stations that located in effective radius (Dobrolsky radius) and the same results was obtained. It states that there is a relation between temperature anomaly behavior and the major earthquakes.

    Keywords: Time Series, Thermal Anomaly, Prediction, Earthquake
  • Somayeh Sanjary, Fatemeh Hadavi *, Marziyeh Notghi Moghaddam, Mohsen Allameh Pages 47-55
    A biostratigraphic study based on calcareous nannofossils was performed on the chalky limestone from the Abderaz Formation in the Mozduran section (Kopet Dagh basin, NE Iran). Semiquantitative estimates of total nannofossil and single species abundances showed that calcareous nannofossil assemblages are common and their preservation is good. In this study 37 species have been identified in chalky limestone beds. The following biohorizons were identified: the first occurrence (FO) of Broinsonia parca parca; the last occurrence (LO) of Marthasterites furcatus; the FO of Ceratolithoides aculeus; and the FO of Uniplanarius sissinghii. Based on nannofossil assemblages' four biozones were determined in this section which is the time equivalent of UC14 to UC15cTP of (Burnett 1998), and CC18 to CC21 of (Roth et al. 1986). According to present biozones, early Campanian to early late Campanian ages are suggested. Calcareous nannofossils allow the detailed reconstruction of paleoecological trends in the chalky limestone beds. The chalky limestone of the Abderaz Formation was deposited in a shallow-marine environment, at relatively low latitude with low primary productivity.
    Keywords: Calcareous nannofossil, Chalky limestone, Abderaz, Kopet Dagh, Iran
  • Amir Bijan Yasrebi *, Ardashir Hezarkhani Pages 56-67
    Resources/reserves classification is crucial for block model creation utilised in mine planning and feasibility study. Selection of estimation methods is an essential part of mineral exploration and mining activities. In other word, resources classification is an issue for mining companies, investors, financial institutions and authorities, but it remains subject to some confusion. The aim of this paper is to determine a resources classification for a Cu block model generated by an Ordinary Kriging (OK) and a Concentration-Volume (C-V) fractal modelling based on estimated variance in Eastern Kahang Cu-Mo porphyry deposit, Central Iran. Variography, block modelling and cell declustering for dataset with respect to Cu concentrations as the main target in this deposit were conducted firstly. Then, Cu distribution model was carried out by the OK and estimated variances were calculated for all voxels. According to a C-V log-log plot, three populations for estimated variances were detected. ‘’Measured’’ resources contain voxels with estimated variances lower than 0.08 and more than 7 samples. Estimated variances varied between 0.08 and 0.24 in which more than 3 samples were engaged for estimation of ‘’Indicated’’ resources. ‘’Inferred’’ resources include estimated variances over 0.24 which are located in marginal parts of this deposit. Results derived via this study reveal that the C-V fractal modelling can be used for resources classification in different ore deposits.
    Keywords: Concentration-Volume (C-V) fractal model, Resources classification, Estimated variance, Eastern Kahang Cu-Mo porphyry deposit
  • Mahmoud Reza Majidifard *, Parvaneh Zavar, Morteza Taherpour Khalil Abad, Masoud Zamani Pedram, Taiebeh Mohtat Pages 68-79
    For the microbiostratigraphical studies, a stratigraphical section (named Dareh-Goshayesh) has been selected in southeast of Maragheh, Northwestern Iran. The thickness of successions in the selected stratigraphic section is measured about 223.6 m. The mentioned studied stratigraphic section is composed of two clastic and carbonate units. This succession unconformably overlies the Lar Formation and is overlain by the Upper Cretaceous strata paraconformably. Based on the micropaleontological studies, a diversified assemblage of foraminifera and calcareous algae has been determined and the age of the studied stratigraphic section is inferred as Late Barremian-Late Aptian. Also, during these studies, four biozones are determined as follows: Palorbitolina lenticularis Range Zone, Balkhania balkhanica range zone, Orbitolina (Mesorbitolina) texana Zone and Orbitolina (Mesorbitolina) parva Zone. This paper presents the first micropalaeontological and lithostratigraphical studies.
    Keywords: Foraminifera, Barremian-Aptian, Eastern Azerbaijan, NW Iran
  • Sara Fakhari *, Alireza Jafarirad, Peyman Afzal, Mohammad Lotfi Pages 80-92
    The Urumieh-Dokhtar Magmatic Belt (UDMB) is the host of many Iranian Cu porphyry deposits. The southern part of this belt, in the Jebal-Barez area, has been less investigated due to the mountainous and rough topography as well as some security confrontations. Porphyry deposits are associated with hydrothermal alteration zones, which can be mapped using the remote sensing data such as Advanced Space borne Thermal Emission and Reflection Radiometer (ASTER). The aim of this study was to identify and detect the alteration zones associated with porphyry systems using ASTER data in Jebal-Barez area, SE Iran. For this reason, seven scenes of ASTER level-1B data which cover the Jebal-Barez area, were pre-processed and then processed by band ratio, false color composite and Spectral Angle Mapper (SAM) methods. The result indicated the presence of extensive phyllic and argillic alteration zones. The argillic alteration is surrounded by border zones of propylitic alteration. Also, a massive granitoid intrusion in NW of the studied area was detected by SAM method and the color composite of 4, 6, and 8 bands of ASTER as a completely altered area (SF area) which strongly needs more detailed exploration and field inspections.
    Keywords: ASTER, Band ratio, False colour composite, Spectral Angel Mapper (SAM), Alteration, Jebal-Barez