Simulation of mineral grades and classification of mineral resources by using hard and soft conditioning data: application to Sungun porphyry copper deposit

The presence of geological units with different grade characteristics mostly leads to problems during the grade modeling process. In special cases, if the area under study has units with small thickness and low grade with respect to the dominant unit of the area, it is difficult to reproduce different grade contents in these units in the simulated grade models because of the low thickness and lack of data in these units. In this study, the local moment constraints method, based on the definition of soft conditioning data reflecting geological knowledge, is investigated for improving simulated grade models under the mentioned conditions. This method is applied for grade simulation at the 1,750 m level of Sungun porphyry copper mine. The studied area is divided into two rock type domains: Sungun porphyry and Dyke. The Sungun porphyry unit is the dominant rock type in the considered area and has, on average, a higher copper grade, while dykes discontinue Sungun porphyry rock units sporadically and most of them are barren of mineralization. It is demonstrated that the use of soft conditioning data makes the simulated grade model closer to reality and improves the reproduction of grade contents considering the rock type units in the area. In the next step, the results obtained from conditional simulation are used for mineral resources classification. To this end, the conditional coefficient of variation is chosen as a criterion for measuring uncertainty and for defining the resources classes. Then, it is shown that uncertainty can be considerably reduced in the prepared models if soft data are considered; as a result, an increase in measured resource classification is observed.     

Collocated cokriging of iron deposit based on a model of magnetic susceptibility: a case study in Morvarid mine,Iran

Arabian Journal of Geosciences - This paper describes a general framework of incorporating magnetic data as prior information in the modeling of an iron deposit based on sparse drilling boreholes....     

Mapping and monitoring of dust storms in Iran by fuzzy clustering and remote sensing techniques

In this research, the frequency of dust storms was prepared at 87 synoptic stations for the period of 1987–2013. These data were classified by means of Fuzzy c-means clustering algorithm. Satellite images of MODIS and brightness temperature index were also used for detection and tracking dust storm of 30 Jun 4 July 2008. The results indicated that Iran is classified in five clusters by the dust-storm-frequencies from which, cluster 5 is reclassified in three clusters because of its wide range. The maximum number of days with dust storms was observed in cluster 1 that includes only Zabol station with the frequency of 790 days with the duration 1987–2013. The minimum number of days with dust storms was observed in cluster 5-3 that includes the stations located in portions of North, Northwest, Northeast Iran and the higher elevations of the Zagros in western Iran. A case study about a severe dust storm in Iran using satellite images indicate that brightness temperature index (BTI) is a desired index for detection and monitoring of dust storms. The source of the investigated dust storms is Iraq and South of the Arabian Peninsula that had influenced the western half of Iran in several days. The frequency of dust storms increased markedly in the west, southwest of Iran and Persian Gulf around as main receptors from emerging dusty areas but it increased slightly in the eastern half of Iran.     

An efficient approach for historical storage and retrieval of segmented road data in Geographic Information System for Transportation

One of the most powerful functions of Geographic Information System for Transportation(GIS-T)is Dynamic Segmentation(DS),which is used to increase the efficiency and precision of road management by generating segments based on attributes.The road segments describing transportation data are both spatially and temporally referenced.For a variety of transportation applications,historical road segments must be preserved.This study presents an appropriate approach to preserve and retrieve the historical road segments efficiently.In the proposed method,only the portions of segments of a time stamp that have been changed into new segments rather than storing the entire segments for every old time stamp are recorded.The storage of these portions is based on the type of changes.A recursive algorithm is developed to retrieve all segments for every old time stamp.Experimental results using real data of Tehran City,Iran justify the strength of the proposed approach in many aspects.An important achievement of the results is that database volume for 2006,2007 and 2008 within the Historical Line Event Table(HLET)is reduced by 70%,80%and 78%,respectively.The proposed method has the potential to prevent from vast data redundancy and the unnecessary storage of entire segments for each time stamp.Since the present technique is performed on ordinary plain tables that are readable by all GIS software,special software platforms to manage the storage and retrieval of historical segments are not needed.In addition,this method simplifies spatio-temporal queries.     

Real-time Uncertain Geological Boundaries Updating for Improved Block Model Quality Control Based on Blast Hole Data: A Case Study for Golgohar Iron Ore Mine in Southeastern Iran

One main problem in the modeling of mineral deposits is to design a block model that divides the deposit into homogeneous subdomains. The spatial uncertainty in the geological boundaries becomes a critical factor prior to the modeling of the ore properties. For this reason, reducing the uncertainty of geological models leads to an improved mineral resource evaluation. This research work addresses the problem of updating the geological models by using actual online-sensor measurement data. A novel algorithm is provided, which integrates the discrete wavelet transform to the Ensemble Kalman Filter for assimilating online-sensor production data into geological models. The geological realizations in each time step are transformed to frequency coefficients and, after each assimilation step, the updated realizations are back-transformed to the original categorical distribution. Furthermore, a reconciliation process is performed to compare the online-sensor data derived from the production blocks and the updated realizations in each time step. The algorithm is illustrated through an application to the Golgohar iron deposit located in SW of Sirjan, Iran, and proves to reproduce the statistical parameters and connectivity values of the primary geological realizations.

     

Hydrogeologic characteristics of the alluvial tuff aquifer of northern Sahand Mountain slopes, Tabriz, Iran

The Tabriz area is a densely populated area of northwestern Iran (more than 1.5 million in population) with a large proportion of its drinking, domestic, industrial and agricultural water supplied from groundwater resources. The average rate of drinking and industrial water use in the city of Tabriz is about 3.45 m³ s^–1. The Plio-Pleistocene unconfined alluvial tuff aquifer (about 1,275 km²), the most important aquifer in the area, has been known for many years as a reliable resource. The greatest estimated thickness of the alluvial tuff lies in the Saidabad area, with 350 m thickness. There are 994 deep and 284 shallow active pumping wells and 83 qanats operate in the alluvial tuff aquifer. The total water withdrawal from all these artificial discharge points has been measured at 72, 3.8 and 17 million m3/year, respectively. Analytical and numerical methods have been applied to the constant rate pumping test data from the Saidabad wellfield (eight pumping and three observation wells). The values of electrical conductivity in the groundwater of alluvial tuff aquifer range from 203 to 960 μS cm^–1 and bicarbonate type water dominates.     

Exploring the potential of location-based social networks data as proxy variables in collective human mobility prediction models

The study of human mobility has gained much attention in recent years. To date, various models have been developed to predict human mobility patterns for intra- and/or inter-city cases. These models incorporate the populations as proxy variables in the place of real variables which cannot be observed easily. However, inaccuracies in predicting human mobility within cities are usually encountered. One source of inaccuracies in intra-city scenarios arises from the fact that cities’ populations are influenced by people from other areas. Therefore, population cannot be regarded as a good proxy variable for movement modeling. The objectives of this article are to introduce new proxy variables for use in current models for predicting human mobility patterns within cities, and to evaluate the accuracy of the predictions. In this study, we have introduced new proxy variables, namely, venues and check-ins, extracted from location-based social networks (LBSNs). In order to evaluate the models, we have compared our results with empirical data obtained from taxi vehicles, based on trip distances and destination population distributions. The Sørensen similarity index (SSI) and R-squared measures were also used to compare the performances of models using each variable. The results show that all models with LBSN variables can capture real human movements better within Manhattan, New York City. Our analytical results indicated that the predicted trips using LBSN data are more similar to the real trips, on average, by about 20% based on the SSI. Moreover, the R-squared measures obtained from regression analyses were enhanced significantly.     

A Preliminary Study on the Aghbolaq(Fe,Cu) Skarn Deposit,Oshnavieh, NW Iran: Constraints on Metasomatic Fluid Evolution

The Aghbolaq skarn deposit is located in the Urumieh-Golpayegan plutonic belt,NW Iran.The garnetite skarn(stage I) has been intensely cross-cut by the magnetite-garnet skarn (stage II) which were,in turn,cut and offset by the orehosting quartz veins/veinlets (stage III).The predominance of andradite (Adr_(82.5–89.1)) and its high Fe~(3+)/Al ratio (up to 1685)apparently supports the high f O_2,salinity and prevalence of magmatic/hydrothermal fluids involved,rather than meteoric waters,during the magnetite-garnet skarn formation.Two major groups of fluid inclusions,namely aqueous (LV,LVS) and aqueous–carbonic (LV_C,LL_CV_C),were recognized in garnet and quartz veins that,especially in growth zones and along intra-granular trails,better display fluid inclusion assemblages (FIAs) than those in clusters.The prograde magnetite-garnet skarn was formed by the metasomatic fluid at relatively high T_h (209–374℃),under a lithostatic pressure of～200 bars.The retrograde mineralized quartz veins were formed at temperatures ranging from 124℃to 256℃,by dilute and less saline(2.57–11.93 wt%Na Cl eq.) hydrothermal fluids under a hydrostatic pressure of～80 bars.The fluid evolution of the Aghbolaq skarn began with an earlier simple cooling of metasomatic fluid during the prograde stage,followed by the later influx of low salinity meteoric fluids during the retrograde stage.     

Geometallurgical Domaining by Cluster Analysis: Iron Ore Deposit Case Study

Natural Resources Research - Geometallurgy integrates many aspects of geology, mineralogy, resource modeling, mine planning, metallurgy, and process control to optimize mining operations....     

Supergene Mass-Balance Study Assuming Zero Lateral Copper Flux Using Geostatistics to Recognize Metal Source Zones in Exotic Copper Deposits

Recognition of effective factors that influence the spatial extension of supergene weathering zones is important both for the identification of high potential areas of exotic deposits and for the cost-effective planning of mining. In particular, recognition of exotic mineralization around porphyry copper deposits early in mine development prevents them from being buried beneath mine infrastructures such as waste dump and tailing structures. Mass-balance modeling, a practical method for determining high potential areas of undiscovered exotic mineralization, investigates important factors in forming exotic deposits. Mass-balance modeling is a two-phase methodology that becomes progressively more detailed. An initial result, presented here as phase 1, is based solely on Cu assays. Phase 2 incorporates relict sulfide mineral studies to improve phase 1 modeling results and computes actual fluxes of copper that escaped vertically downward from the leached cap to form the enrichment blanket and then flowed laterally away to form exotic mineralization. In addition, geostatistical approaches, especially sequential Gaussian simulation, are useful tools for investigating the spatial relationships and modeling of mass-balance results in phase 1 studies. This paper introduces a method for interpolation and downscaling of the preliminary mass-balance analysis (phase 1) to highlight the role of geological features in the evolution of the supergene process. Using only copper assays without any need for relict sulfide mineralogy, this approach can be used to approximately identify the geographic direction of metal movement in exotic copper deposits, and thus serve as an initial exploration guide in prospecting for exotic deposits. For this, a vertical columnar block model was constructed for each of the supergene weathering zones and preliminary analysis of mass balance was conducted to reconstruct the apparent total leached zone column height assuming zero lateral flux. This analysis was applied to each of the vertical block model columns. The results of mass balance were interpolated in a 5?×?5 m grid by sequential Gaussian simulation method, and the simulated surface of the total leached zone was conflated with geological features. The roles of topography, argillic alteration and linear structures were identified in the transport of supergene solutions in the Miduk porphyry copper deposit of Iran. In the northern section of the deposit, which is in accordance with the topography gradient and the presence of advanced argillic alteration zone, the computed top total of leaching is below the actual surface topography, whereas the hypogene isograd curves confirm the expansion of primary copper in these areas. The northern section of the deposit was introduced as a susceptible area for the removal of copper-bearing solutions from the supergene enrichment system.