Geochemical investigation of rare earth and other strategic elements in stream sediments of the Khoy 1:100,000 geological sheet area, using catchment basin and principal component analysis methods

Document Type : Research Article

Authors

Department of Mining and Metallurgy, Yazd University

10.29252/anm.7.14.23

Abstract

Summary
Principal Component Analysis (PCA) and Catchment Basin Analysis (CBA) methods have important role in investigation of stream sediment geochemical data and can have special contribution in prospecting programs and other exploration steps. In this study, the data of 843 stream sediment samples from Khoy 1:100,000 geological sheet area in West Azerbaijan, were investigated using PCA and CBA methods. At first, dimension of variables such as REEs as well as Cu, Pb, Zn, Cr, Au and Ag was decreased using principal component analysis (PCA) and the main principal components were selected for further investigation and finally the correlation of each parameter with achieved factors were given. Then, the background values were calculated and local anomalies were separated using catchment basin analysis on the basis of real area and upstream geological units of catchment. In addition, it is demonstrated that catchment basin analysis is able to better discriminate local anomalies. Consequently two mentioned methods obviously can validate each other.Briefly, in this research, the rare earth and other strategic elements in stream sediments samples of the Khoy 1:100,000 geological sheet area, have been investigated. The background values were calculated and local anomalies were separated using catchment basin analysis on the basis of real area and upstream geological units of catchment. Threshold level method was used for separation of anomalies from background. Also, by principal component analysis (PCA) method, the main factors were delineated. Results obtained from PCA method, were estimated using ordinary kriging and finally these two methods were compared. Consequently two mentioned methods obviously can validate each other.
                                                                                                                                                                                           
Introduction                  
Aggregation of elements in stream sediments depends on the stream network, area and topography slope of catchment and upstream lithological units. Investigation of these sediments using catchment basin analysis and principal component analysis methods, obviously introduces elements dispersion and prevents demonstrating unreal anomalies. The PCA method is useful in identification of complicated structure, indexing and reduction of data dimension. Because of existence of vast alluvial plains, alluvial fans, coasts and vast basins in Iran, geochemical data analysis by CBA method can lead us to explore the valuable mineral resources to reach sustainable development. The above mention methods will cause to find probable mineralization regions.
 
Methodology and Approaches
In this study, for investigation of stream sediments geochemical anomalies, different steps such as data processing, separation of basins, calculation of local anomaly using CBA and PCA methods have been used for REEs and some other trace elements. In CBA method, the basins were separated by ArcGIS software and Archydro tools extension and then, real area of geological units for all catchments were calculated. Finally, using real area and application of upstream lithologies in given equations, the background values were calculated and local anomalies were separated. In PCA method, the main component of each elements were delineated, using ordinary kriging, values of each main factors have been estimated in unsampled regions.
 
Results and Conclusions
Results and geochemical maps obtained by BCA and PCA methods demonstrate that catchment basin analysis is able to better discriminate local anomalies and these anomalies have been correlated with the ordinary kriging maps obtained from principal component analysis and these two mentioned methods, obviously can validate each other.

Keywords

Main Subjects


]1[ Bonham-Carter. G.F.; 1994; “Geographic Information Systems for Geoscientists: Modelling With GIS”, Pergamon, Oxford.
]2[ Carranza. E.J.M.; 2004a; “Usefulness of stream order to detect stream sediment geochemical anomalies”, Geochemistry: Exploration, Environment, Analysis 4, 341–352.
]3[ Carranza. E.J.M.; 2008; “Geochemical anomaly and mineral prospectivity mapping in GIS”, Handbook of Exploration and Environmental Geochemistry, vol. 11. Elsevier, Amsterdam.
]4[ Carranza. E.J.M.; 2010a; “Catchment basin modelling of stream sediment anomalies revisited: incorporation of EDA and fractal analysis”, Geochemistry, Exploration, Environment, Analysis 10, 171–187.
]5[ Carranza. E.J.M.; 2010b; “Mapping of anomalies in continuous and discrete fields of stream sediment geochemical landscapes”, Geochemistry, Exploration, Environment, Analysis 10, 171–187.
]6[ Carranza. E.J.M.; Hale. M.; 1997; “A catchment basin approach to the analysis of geochemical–geological data from Albay province, Philippines”, Journal of Geochemical Exploration 60, 157–171.
]7[ Óor. L.; Horváth. I.; Fügedi. U.; 1997; “Low-density geochemical mapping in Hungary”, Journal of Geochemical Exploration 60, 55–66.
]8[  Spadoni. M.; Cavarretta. G.; Patera. A.; 2004; “Cartographic techniques for mapping the geochemical data of stream sediments: the sample catchment basin, approach”. Environmental Geology 45, 593–599.
]9[ Jollife. I.T.; 1986; “Principal component analysis”, Springer-Verlag, New York.
]10[ Boruvka. L.; Vacek. O.; Jehlicka. J.; 2005; “Principal component analysis as a tool to indicate the origin of potentially toxic elements in soils”, Geoderma 141 (3–4), 370–383.
]11[ Reis. A.P.; Sousa. A.J.; Cardoso Fonseca. E.; 2003; “Application of geostatistical methods in gold geochemichal anomalies identification (Motemor-o-Novo,Portugal)”, Journal of Geochemical Exploration 77 (1), 45–63.
]12[ Tavares. M. T.; Sousa. A. J.; Abreu. M.M.; 2008; “Ordinary kriging and indicator kriging in the cartography of trace elements contamination in São Domingos mining site (Alentejo, Portugal)”, Journal of Geochemical Exploration 98, 43–56.
]13[ Pasyar, A.; Mohammad Torab, F.; 2014; “Stream sediment geochemical anomaly separation on the basis of catchment basin analysis in the Khoy 1:100,000 geological sheet area, West Azerbaijan”, 33rd National Geosciences Symposium, In Persian.
]14[ Rose. A.W.; Dahlberg. E.C.; Keith. M.L.; 1970; “Multiple regression technique for adjusting background values in stream sediment geochemistry”, Economic Geology 65(2): 156-165.
]15[ Abdolmaleki. M.; Mokhtari. A.R.; Akbar. S., Alipour-Asll. M.; Carranza. E.J.M.; 2014; “Catchment basin analysis of stream sediment geochemical data: Incorporation of slope effect”, Journal of Geochemical Exploration 140, 96-103.
]16[ Hawkes. H.E.; 1976; “The downstream dilution of stream sediment anomalies”, Journal of Geochemical Exploration 6(1-2): 345-358.
]17[ Bonham-Carter. G.; Goodfellow. W.D.; 1984; “Autocorrelation structure of stream sediment geochemical data: interpretation of zinc and lead anomalies, Nahanni river area, Yukon Northwest Territories, Canada. In: G. Verly et al. (Eds.)”, Geostatistics for Natural Resources Characterization, Part 2, D. Reidel, Dordrecht, pp. 817-829.
]18[ Bonham-Carter. G.F.; Goodfellow. W.D.; 1986; “Background corrections to stream geochemical data using digitized drainage and geological maps: application to Selwyn Basin, Yukon and Northwest Territories”, Journal of Geochemical Exploration 25(1-2): 139-155.
]19[ Wellmer. F.W.; 1998; “Statistical Evaluations in Exploration for Mineral Deposits”, Springer New York, P.379.