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1.
Shahab Shahbeik Peyman Afzal Parviz Moarefvand Mania Qumarsy 《Arabian Journal of Geosciences》2014,7(9):3693-3704
Estimation of mineral resources and reserves with low values of error is essential in mineral exploration. The aim of this study is to compare inverse distance weighted (IDW) and ordinary kriging (OK) methods based on error estimation in the Dardevey iron ore deposit, NE Iran. Anisotropic ellipsoid and variograms were calculated and generated for estimation of Fe distribution by both methods. Density, continuity of ore and waste, the number of points involved, and the discretization factor in the estimation of ore and waste boundaries were determined and the resource estimated by IDW and OK methods. Estimation errors were classified based on JORC standard, and both methods were compared due to distribution of error estimation. Results obtained by the study indicate that error estimation of OK method is less than IDW method and that the results of OK method are reliable. 相似文献
2.
Ali Parhizkar Mohamad Ataei Parviz Moarefvand Vamegh Rasouli 《Arabian Journal of Geosciences》2012,5(6):1279-1288
Many of the open-pit mines suffer from the lack of reconciliation between estimated and actual grades. In a mining operation, grade reconciliation is the comparison between the values of the estimated grade calculated in exploration stage and the actual grade obtained from more reliable data such as blast holes?? samples. Many different factors affect the degree of reconciliation in a mining operation. In this paper, the factors related to estimated grade which affect the reconciliation process in the exploration stage of the orebody are investigated. These factors constitute the sources of uncertainty for the upcoming phases of the mining life. Among these parameters, the inherent variability, statistical uncertainty, and systematic uncertainty are the most important factors. In this work, these parameters are studied in further detail, and, accordingly, for each of these uncertainties, a correction factor is determined in the proposed model. The model was applied to the study of real data taken from an iron open-pit mine in Iran. The results of the case study indicated that the systematic uncertainty, inherent variability, and statistical uncertainty are, in order, the main sources of uncertainty on grade reconciliation process. Applying the correction factors to estimated grade values has increased the amount of grade reconciliation from 10%, at original condition, to 50%, at new condition, in the case study. 相似文献
3.
Marzieh Shademan Khakestar Hossein Hassani Parvizz Moarefvand Hassan Madani 《Journal of the Geological Society of India》2016,87(1):97-104
Almost all collapses of rock slopes especially in open pit mines are related to discontinuities such as bedding planes, faults and major joints.Geostatistical assessments can be used for understanding the distribution of regionalized variables in any spatial study. In this paper3D spatial dispersion of the fault planes in the Gole Gohar open pit iron mine, located in Kerman province, south east of Iran, is modeled. Then, regionalized variable theory is used to analyze and interpret spatial distribution of the following geotechnical parameters: Geological strength index (GSI), Rock quality designation (RQD), Cohesion (C) and angle of internal friction (f). In order to define regionalized variable distribution, variogram functions were determined for identifying the regional behavior. Structural analysis of variograms showed that the mentioned parameters have spatial structures that make it possible to set up a geostatistical model to predict their values for each non-sampled block on the pit wall. Results showed that there is a relation between the low values of geotechnical parameters and the existence of discontinuities around the pit area. The role of discontinuities in the occurrence of collapses in the area was clearly demonstrated by comparing the estimated parameters models and the model of discontinuities dispersion. 相似文献
4.
Peyman Afzal Ahmad Khakzad Parviz Moarefvand N. Rashidnejad Omran Bijan Esfandiari Younes Fadakar Alghalandis 《Journal of Geochemical Exploration》2010,104(1-2):34-46
Geochemical anomaly separation using the concentration–area (C–A) method at Kahang (Gor Gor) porphyry system in Central Iran is studied in this work. Lithogeochemical data sets were used in this geochemical survey which was conducted for the exploration for Cu mineralization in dioritic and andesitic units at Kahang Cu–Mo porphyry system. Similar surveys were also carried out for Mo and Au exploration in these rock units. The obtained results have been interpreted using rather extensive set of information available for each mineralized area, consists of detailed geological mapping, structural interpretation and alteration data. Anomalous threshold values for the mineralized zone were computed and compared with the statistical methods based on the data obtained from chemical analysis of samples for the lithological units. Several anomalies at a local scale were identified for Cu (224 ppm), Mo (63 ppm), and Au (31 ppb), and the obtained results suggests existence of local Cu anomalies whose magnitude generally is above 1000 ppm. The correlation between these threshold values and ore grades is clearly interpreted in this investigation. Also, the log–log plots show existence of three stages of Cu enrichment, and two enrichment stages for Mo and Au. The third and most important mineralization event is responsible for the presence of Cu at grades above 1995 ppm. The identified anomalies in Kahang porphyry system, and distribution of the rock types, are mainly monzodiorite and andesitic units, do have special correlation with Cu and monzonitic and dioritic rocks, especially monzodioritic type, which is of considerable emphasis. The threshold values obtained for each element are always lower than their mean content in the rocks. The study shows threshold values for Cu is clearly above the mean rock content, being a consequence of the occurrence of anomalous accumulations of phyllic, argillic and propyllitic alterations within the monzonitic and dioritic rocks especially in monzodioritic type. The obtained results were compared with fault distribution patterns which reveal a positive direct correlation between mineralization in anomalous areas and the faults present in the mineralized system. 相似文献
5.
Failure patterns of geomaterials with block-in-matrix texture: experimental and numerical evaluation 总被引：1，自引：0，他引：1
In nature, due to complex geological process, some geomaterials with block-in-matrix texture exist that characterized by a heterogeneous structure including rock blocks embedded in a small-grained matrix. In literature, these materials also referred as bimrock (block-in-matrix rock). Typical examples of these complex materials are conglomerates, breccias, glacial till, coarse-grained alluviums, and mélanges formations. When dealing with these complex media in engineering, it is important to understand the process by which the geomaterials fail under common loading conditions. In this paper, artificial bimrock specimens were prepared for different percentage of rock block proportions. The failure mechanism under uniaxial compression and indirect tension loading were studied. In order to compare the failure modes with homogeneous specimens, a numerical simulation of laboratory tests including uniaxial compression and Brazilian test was conducted on a typical bimrock and a homogenous specimen. The results showed different features of failure pattern for bimrocks with high proportions of rock blocks in comparison with homogeneous specimens. According to the experimental results, three main features were observed including a continuous tortuous failure surface, multiple localized shear failure surfaces, and detachment of rock blocks from the periphery of specimens. 相似文献
6.
A. Mataji P. Moarefvand S. Babaie Kafaki M. Madanipour Kermanshahi 《International Journal of Environmental Science and Technology》2010,7(4):629-638
Physiographic factors along with edaphic conditions play a crucial role in establishment of plant species throughout a region. Identification of the most effective factors is of high importance in sustainable management of a forest ecosystem. This study aims to investigate the relationships between understory vegetation and some environmental factors in natural forest ecosystems. This study has been carried out among the Fagetum orientalis communities of Ramsar Region, located in the north of Iran. For this purpose, 105 releves were sampled by a randomized-systematic method throughout the study area, using the Braun-Blanquet scale. Physiographic parameters such as elevation, as well as slope and orientation were measured. By identification of the herb-layer vegetation contained in each sampling, vegetation composition and cover abundance of species were separately identified. Then, the aforementioned properties of soil were entirely measured in the taken samples. Cluster analysis and detrended correspondence analysis have been applied to classify the site. Moreover, in order to determine the relation between species composition and environmental factors, canonical correspondence analysis was used. Results showed a significant relation between distribution of plant types and environmental factors. Eventually, environmental factors including slope, orientation, silt percent, pH, organic matter and soluble phosphorous were among the most effective factors in establishment of Hedera pastuchowii, Solanum kieseritzkii, Oplismenus undulatifolius, Sedum stoloniferum, Rubus hyrcanus and Saxifraga cymbalaria species. 相似文献
7.
Delineation of mineralization zones in porphyry Cu deposits by fractal concentration–volume modeling
Peyman Afzal Younes Fadakar Alghalandis Ahmad Khakzad Parviz Moarefvand Nematolah Rashidnejad Omran 《Journal of Geochemical Exploration》2011
The purpose of this study was to identify the various mineralization zones especially supergene enrichment and hypogene in two different Iranian porphyry Cu deposits, based on subsurface data and by using the proposed concentration–volume (C–V) fractal method. The Sungun and Chah-Firuzeh porphyry Cu deposits, which are situated in NW and SE Iran, respectively, were selected for this study. Straight lines fitted through log–log plots showing C–V relations for Cu were employed to separate supergene enrichment and hypogene zones from oxidation zones and barren host rocks in the two deposits and to distinguish a skarn mineralized zone from the hypogene zone in Sungun deposit. In the proposed C–V fractal method, the identification of mineralization zones is based on power–law relationships between Cu concentrations and the volume of rocks hosting porphyry Cu mineralization. Separate subsurface data from the two deposits were analyzed by C–V fractal method and the results have been compared with geological models which included alteration and mineralogical models. The comparison shows that the interpreted zones based on the C–V fractal method are consistent with the geological models. The proposed C–V method is a new approach to defining zones in a mineral deposit and there was no commercial software available to perform the relevant calculations; therefore, a fractal concentration–volume (FCV) software was designed by the authors to achieve this goal. 相似文献
8.
Alireza Mohammadi Ahmad Khakzad Nematolah Rashidnejad Omran Mohammad Reza Mahvi Parviz Moarefvand Peyman Afzal 《Arabian Journal of Geosciences》2013,6(11):4387-4398
The goal of this study is to separate different mineralized zones in Dareh-Ashki gold deposit located in Muteh Complex, Central Iran, by using number–size (N-S) fractal model. The N-S log–log plot shows seven geochemical populations and four Au-mineralized zones. Based on obtained results, Au thresholds are 0.17, 0.32, 6.3, and 12.6 ppm which represent weakly, moderately, highly, and extremely mineralized zones in terms of Au grades, respectively. Au values lower than 0.17 ppm illustrate wall rocks. Main mineralization stage of gold commences from 6.3 ppm in this deposit. The moderately mineralized zone with Au values between 0.32 and 6.3 ppm has occupied the biggest part of the studied deposit. However, highly (with Au values between 6.3 and 12.6 ppm) and extremely (higher than 12.6 ppm) mineralized zones have small extension. Correlation between geological model and results from N-S fractal model reveals that the gold mineralized zones specifically the moderately mineralized zone are situated in green schist units. 相似文献
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10.
Natural Hazards - Ground vibrations induced by the blasting of explosives can cause damage to the slope stability of mines. The important indicators of rock mass such as the geological... 相似文献