Z. Khajehmiri; M. R. Shayestehfar; H. Moeinzadeh
Abstract
Due to high cost, risk and time consuming nature of field operations and mineral explorations, the discovery of probable mineralization area is profoundly important. Thus, preparations of potential mineral map by means of GIS techniques for compilation all exploration factors is an essential matter. ...
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Due to high cost, risk and time consuming nature of field operations and mineral explorations, the discovery of probable mineralization area is profoundly important. Thus, preparations of potential mineral map by means of GIS techniques for compilation all exploration factors is an essential matter. Various methods of mineral potential assessment have been developed. One of those most efficient techniques, based on nature of geology and mineral phenomena, is Analytical Hierarchy process (AHP) and Fuzzy Analytical Hierarchy process (FAHP). In this investigation, in order to prepare probable porphyritic gold copper zones map in 1:100000 sheet of south of Sehchangi, AHP and FAHP have been implemented. In the study area, the witness layers including geology layers (thermal source rock and host rock), alteration, tectonic and geochemical layers depending on target (porphyritic gold- copper mineralization) are weighted and then compiled by aid of AHP and FAHP. In final compiled map resulted by two mentioned methods, the anomalous zones are separated by fractal method. The comparison of final maps of probable porphyritic gold - copper mineralization zones indicate that the results derived byFAHP is significantly more precise than AHP. Anomalous zones derived by this method (FAHP) are evaluated, anomalous zone 1 derived by FAHP is approved by previous analysis. The analysis results of mineralized samples of anomaly 2 indicate that samples have experienced copper enrichment and moreover, gold and arsenic elements are enriched as well. The results presented here and results of previous analyses approve mineral potential assessment derived by Fuzzy Analytical Hierarchy process (FAHP).
F Kamranzad; E Mohasel Afshar; M Mojarab; H Memarian
Abstract
Landslide is one of the natural phenomena which can cause catastrophic losses or damages in life and property each year. Hence, it is very important to recognize landslide-prone areas and apply methods to prevent or reduce slope instabilities and landslide hazard and risk. For this purpose, landslide ...
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Landslide is one of the natural phenomena which can cause catastrophic losses or damages in life and property each year. Hence, it is very important to recognize landslide-prone areas and apply methods to prevent or reduce slope instabilities and landslide hazard and risk. For this purpose, landslide hazard zonation is one of the indirect and efficient methods. This study aims to apply data-driven and AHP methods to provide a zonation map of landslide hazard potential in the Tehranprovince of Iran. First, six essential and available factors including slope, slope direction, geologic background, distance from faults, earthquake acceleration and rainfall were selected to be classified in GIS based on engineering judgment. By superposing data layers over landslide distribution map in data-driven method and expert judgment in AHP method, layers and sub-layers were weighted and combined. The landslide-hazard zonation map was then produced for each of the methods in GIS. Results showed that in data-driven method 92.9% of landslides fall into the perilous zone (i.e. hazardous and very hazardous zones) having an area of 7135.15 km2, which is 37.2% of total area of Tehran province. For the AHP method, 96.47% of the landslides were in perilous zone with an area of 10344.7 km2, which is 53.9% of the total area of the province. Finally, the ratio of percentage of landslides in the perilous zone to the percentage of total area of the zone was calculated. The ratio is 2.5 for the data-driven and 1.79 for the AHP method. The larger ratio in the data-driven method indicates its better consistency than the AHP method, implying more coverage of landslides in a smaller perilous area by the data-driven method. This result represents better accuracy of the data-driven method than the AHP method in landslide hazard zonation.
M Kamani; A Uromeihy; M Joorabchi
Abstract
Roads are of linear engineering projects passing various rock units and geological conditions, so it is necessary to engage the engineering geological studies along the way. The studies continue until the end of the construction and operation. In the route selection process, large volumes of data and ...
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Roads are of linear engineering projects passing various rock units and geological conditions, so it is necessary to engage the engineering geological studies along the way. The studies continue until the end of the construction and operation. In the route selection process, large volumes of data and different track conditions are facing. To perform this manually is time consuming and not accurate enough. This study examines the status of engineering geology freeway route Qazvin - Rasht in Roudbar discussed in this context, the factors affecting engineering geology route selection and construction of the freeway, using the Analytical Hierarchy Process (AHP) and Expert Choice software to give weight of these factors, according to their suitability for the construction of freeways, and then layers weighted overlay in GIS software and the final map has been prepared. The final map shows the quality of route engineering geological conditions, which is provided for both surface and subsurface (tunnels) with the least error. Since the procedure for engineering geological survey route is a new method, it requires further investigation and to test in other places in order to be much more modified and corrected. On the other hand, this model can be used for other engineering geological investigations due to high flexibility of this model.
SH Aboutorab; A Khakzad; F Gharib; S Mehdizadeh Tehrani
Abstract
The 1:100000 sheet of Ardestan is located in the south part of 1:250000 quadrangle of Kashan at 52º to 52º, 30 E and 33º to 33º, 30N in the north west of Isfahan province and Orumieh-Dokhtarvolcanic belt.Most of the rock units' ofArdestanregion include medium to basic volcanic ...
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The 1:100000 sheet of Ardestan is located in the south part of 1:250000 quadrangle of Kashan at 52º to 52º, 30 E and 33º to 33º, 30N in the north west of Isfahan province and Orumieh-Dokhtarvolcanic belt.Most of the rock units' ofArdestanregion include medium to basic volcanic and pyroclastic rocks, which are related to middle-upper Eocene volcanism phase. Intrusive rocks of this region have low-acidic to acidic combinations and belong to the shallow magmatism phase of Oligocene-Oligo Miocene and sub-volcanic activities of Pliocene. These intrusive rocks cause hydrothermal alteration and then mineralization of elements such as Cu, Mo, Au, Pb, Zn, and Fe. In this thesis, by employing the existing geological maps, systematic geochemical explorations, and known mineral indices together withthe derived information from processing of the existing airborne geophysics and satellite data (e.g. faults, hydrothermal alterations, total magnetic intensity and rock units), a number of different databases were formed.Then, by using the new weighted score method of analytic hierarchy process (AHP),these databases (also known as layers) are weighed based on the predicted genetic model of the region. These weighed layers are then modeled in the GIS system by using the index overlay method. Based on the achieved results from this study, promising area maps for Epithermal Gold is prepared.According to our field observations, sampling and laboratory analyses of the promising areas, 5areas with first priority are considered to have economical potentials and are introduced for the next phases of explorations.
