ORIGINAL PAPER Application of multifractal modeling technique in systematic lithogeochemical survey to identify Au–Cu anomalies in the Siah-Jangal area, Southeastern of Iran Zahra Mokhtari & Mohammad Boomeri & Sasan Bagheri Received: 17 November 2014 /Accepted: 24 February 2015 # Saudi Society for Geosciences 2015 Abstract Identifying the geochemical anomalies from back- ground is a fundamental task in exploration geochemistry. This research is based on the application of concentration–area (C–A) method at the Siah-Jangal Au porphyry system in south- eastern Iran. Lithogeochemical datasets (n =399) were used in this geochemical survey which was conducted for the explora- tion for Au mineralization. Moreover, similar surveys were also carried out for As, Cu, and Mo exploration in this region. 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 iden- tified for Au (281 ppb), As (649 ppm), and Cu (20 ppm). The obtained results suggest existence of local Au anomalies that its magnitude generally is above 400 ppb. The C–A log–log plots show existence of three stages of Au and Cu enrichment. The second and most important enrichment event is responsible for the presence of Au at grades above 400 ppb. The obtained results have been interpreted using rather extensive set of infor- mation available for the study area, consisting of structural in- terpretation and alteration data. Various structural features and corresponding alteration show that the geologic structures play an important role in the discrimination of geochemical anoma- lies and element distribution in the Siah-Jangal area. Keywords Geochemical anomaly . Porphyry system . Concentration–area method . Multifractal . Thresholds . Siah-Jangal . Iran Introduction The Separation of geochemical anomalies from background values in areas is one of the most fundamental tasks in the fields of mineral exploration and mineral resource assessment. Since geochemical elements can provide important and direct clues related to the presence of mineral deposits, geochemical anomalies will continue playing an important role in mineral exploration (Cheng et al. 1994; Cheng 1999; Grunsky and Smee 1999; Harris et al. 1999, 2000; Chen et al. 2001; Singer and Kouda 2001). In the past recent years, geochemical anomalies have been identified by means of various methods. Some of these processing methods come from the develop- ments of theoretical geostatistics, and other from the theory of multifractals (e.g., Carranza 2008; Deng et al. 2010; Afzal et al. 2011, 2013, 2014; Pazand et al. 2011; Cheng 2012; Hashemi and Afzal 2013; Wang et al. 2012; Zuo 2011; Zuo et al. 2012). The statistical methods have been widely used to determine threshold values separating background populations from anomalies (e.g., Carranza 2008; Zuo 2011; Cheng 2012). These methods are only applicable to cases that the geochem- ical data follows a normal distribution. Moreover, statistical methods e.g., by histogram analysis or Q–Q plots assuming normality or log normality and do not consider the shape, extent and magnitude of anomalous and geological environ- ments areas (Rafiee 2005) and therefore may fail to recognize anomalies in regions with high background values close to anomalous values, or miss weak anomalies in regions with known mineral deposits (Hassanpour and Afzal 2011). Fractal theory is one of the non-linear mathematics which considers the geometry property of geochemical landscape and established by Mandelbrot (1983). The word BFractal^ is driven from the Latin word Bfractus^, meaning broken, which utilized for the objects that were too irregular to be Z. Mokhtari (*) : M. Boomeri : S. Bagheri Department of Geology, Faculty of Sciences, University of Sistan and Baluchestan, Zahedan, Iran e-mail: Zahra.mokhtari1985@gmail.com Arab J Geosci DOI 10.1007/s12517-015-1860-1