Mahyar Yousefi - Academia.edu (original) (raw)

Papers by Mahyar Yousefi

فصلنامه علمی-پژوهشی علوم زمین, Nov 22, 2011

Iranian Journal of Watershed Management Science and Engineering, Mar 10, 2019

Weighted drainage catchment basin mapping of geochemical anomalies using stream sediment data for... more Weighted drainage catchment basin mapping of geochemical anomalies using stream sediment data for mineral potential modeling

In this work, we present logistic-based mineral prospectivity mapping (MPM) methods concerning wi... more In this work, we present logistic-based mineral prospectivity mapping (MPM) methods concerning with assigning weights of exploration indicators, without contribution of training sites as in supervised MPM and without using userjudged weights as in unsupervised MPM, to modulate the problems of stochastic and systemic errors. In addition, we discuss the ability of prediction-area plot as a tool to assess and compare evidential layers and prospectivity models. 

Applied Geochemistry, 2022

Frontiers of Earth Science, 2021

Identifying geochemical anomalies related to ore deposition processes facilitates the practice of... more Identifying geochemical anomalies related to ore deposition processes facilitates the practice of vectoring toward undiscovered mineral deposit sites. In districtscale exploration studies, analysis of dispersion patterns of ore-forming elements results in more-reliable targets. Therefore, deriving significant geochemical footprints and mapping the ensuing geochemical anomalies are of important issues that lead exploration geologists toward anomaly sources, e.g., mineralization. This paper aims to examine the effectiveness of local relative enrichment index and singularity mapping technique, as two methods of local neighborhood statistics, in the delineation of anomalous areas for further exploration. A data set of element contents obtained from stream sediment samples in Baft area, Iran, therefore was applied to illustrate the procedure proposed. The close relationship between anomalous patterns recognized and known Cu-occurrences demonstrated that the procedures proposed can efficiently model complex dispersion patterns of geochemical anomalies in the study area. The results showed that singularity mapping method is a better technique, compared to local relative enrichment index, to delineate targets for follow-up exploration in the area. We made this comparison because, as pointed out by exploration geochemists, dispersion patterns of geochemical indicators in stream sediments vary in different areas even for the same deposit type. The variety in the dispersion patterns is due to the operation of post-mineralization subsystems, which are affected by local factors such as landscape of the areas under study. Therefore, the effectiveness of the methods should be evaluated in every area for every targeted deposit.

International. Journal of Mining & Geo-Engineering, 2015

In this research, recognition of karstic water-bearing zones using the management of exploration ... more In this research, recognition of karstic water-bearing zones using the management of exploration data in Kal-Qorno valley, situated in the Tepal area of Shahrood, has been considered. For this purpose, the sequential exploration method was conducted using geological evidences and applying remote sensing and geoelectrical resistivity methods in two major phases including the regional and local scales. Thus, geological structures and lithological units in regional scale have been investigated for groundwater potential. In this regard, suitable potential maps have been provided in the geographical information system (GIS) environment, using fuzzy data-driven and knowledge-driven methods. To obtain the final karstic water potential model, the prepared maps were combined using fuzzy ‘AND’ operator. In the local scale, geoelectrical surveys were conducted in the recognized high potential zones. Consequently, the results of geological investigations, analysis of lineaments extracted from s...

Applied Geochemistry, 2021

Abstract Selection of non-deposit sites is a challenging issue affecting the application of super... more Abstract Selection of non-deposit sites is a challenging issue affecting the application of supervised algorithms for modeling mineral exploration targets. For this, equal number of deposit and non-deposit sites has been widely applied for training purposes. In this paper, we investigated the effect of changes in the number of non-deposit sites on the effectiveness of exploration targeting models while the number of deposit sites is constant. The results obtained demonstrated that exploration targeting models are affected by the ratio of non-deposit and deposit sites. Thus, balancing between the number of deposit and non-deposit sites is an efficient way to produce more-reliable exploration targets when supervised algorithms are applied for modeling. The idea of this research came from the fact that mineralization is a rare event, and therefore, in a region of interest number of non-deposit sites is much more than that of deposit events. To illustrate the procedure proposed, we used an exploration dataset of porphyry Cu mineralization in Chahargonbad area, SE Iran. A sequence application of self-organizing map and multilayer perceptron neural network algorithm was applied to better illustration of the changing effects of the number of non-deposit sites on the ensuing exploration targeting models.

Proceedings, 2018

In regional exploration, layers of geochemical signatures play an important role for target gener... more In regional exploration, layers of geochemical signatures play an important role for target generation of mineral deposits. In this paper, continuously-weighted geochemical signatures of podiform-type chromite deposits were first generated through a logistic-based method. Then, the efficient geochemical signatures integrated using a fuzzy S-norm operator for generation of a geochemical model. The results demonstrated that the generated geochemical model is a stronger predictor compared to each of the individual layers of geochemical signature and could be utilized efficiently for further exploration of the deposit-type sought in the study area.

Journal of Geochemical Exploration, 2012

Integration of stream sediment geochemical data with other types of mineral exploration data, esp... more Integration of stream sediment geochemical data with other types of mineral exploration data, especially in knowledge-driven mineral potential mapping (MPM), is a challenging issue. In this regard, multivariate analyses (e.g., factor analysis) are generally used to extract significant anomalous geochemical signature of the mineral deposit-type sought. In this study, we used stepwise factor analysis to generate a geochemical mineralization probability index (GMPI) through a new approach to create stream sediment geochemical evidential maps. GMPI is a weight that can be mapped, and hence, can be used as an evidential map in MPM. Using stepwise factor analysis enhances recognition of anomalous geochemical signatures, increases geochemical anomaly intensity and increases the percentage of the total explained variability of data. With the GMPI, we developed a new data-driven fuzzification technique for (a) effective assignment of weights to stream sediment geochemical anomaly classes, and (b) improving the prediction rate of mineral potential maps and consequently increasing exploration success. Furthermore, the predictive capacity of each stream sediment geochemical sample for prospecting the deposit-type sought upstream of its location can be evaluated individually using GMPI. In addition, the GMPI can be used efficiently in knowledge-driven MPM as a new exploratory data analysis tool to generate a weighted evidential map in less explored areas. In this paper, we successfully demonstrated the application of GMPI to generate a reliable geochemical evidential map for porphyry-Cu potential mapping in an area in Kerman province, southeast of Iran.

Journal of Mining and Environment, 2021

There are different exploration methods, each of which may introduce a number of promising explor... more There are different exploration methods, each of which may introduce a number of promising exploration targets. However, due to the financial and time constraints, only a few of them are selected as the exploration priorities. Instead of the individual use of any exploration method, it is common to integrate the results of different methods in an interdependent framework in order to recognize the best targets for further exploration programs. In this work, the continuously-weighted evidence maps of proximity to intrusive contacts, faults density, and stream sediment geochemical anomalies of a set of porphyry copper deposits in the Jiroft region of the Kerman Province in Iran are first generated using the logistic functions. The weighted evidence maps are then integrated using the union score integration function in order to model the deposit type in the studied area. The weighting and integration approaches applied avoid the disadvantages of the traditional methods in terms of carry...

Journal of Geochemical Exploration, 2022

Natural Hazards

Landslide is a type of natural hazards causing many casualties in mountainous and rainy areas. Th... more Landslide is a type of natural hazards causing many casualties in mountainous and rainy areas. Therefore, recognizing areas those that have potentials for happening such type of hazards is an important task. For this, methods of landslide susceptibility mapping, categorized mainly into two general data- and knowledge-driven approaches, have been widely developed and applied. In this regard, stochastic and systemic errors, respectively, associated with adequacy in the number of known landslide locations and subjectivity of expert judgment applied to assign weights of landslide conditioning factors are two main issues affecting the data- and knowledge-driven approaches. These issues are, in fact, types of bias and uncertainties that adversely affect landslide susceptibility mapping practices. This paper aims to adapt continuous fuzzification and geometric average multi-criteria decision-making approaches to overcome the aforementioned disadvantages of the existing landslide susceptibility mapping methods. In the method proposed weights of landslide conditioning factors are continuously assigned without using known landslide locations as training points, and without using expert opinion in categorization of values of landslide conditioning factors into arbitrary classes and assigning subjective weights. We applied the procedure proposed on a dataset of Oshvand watershed, Hamadan Province, Iran, to demonstrate its effectiveness. The results demonstrated that the continuous weighting method applied is more reliable than the existing methods those which apply classified values of landslide conditioning factors.

Journal of Geochemical Exploration

$Research paper thumbnail of Stream sediment geochemical data analysis for district-scale mineral exploration targeting: Measuring the performance of the spatial U-statistic and C-A fractal modeling$