Comparison of concentration-area (C-A) fractal method and singularity index in separation of geochemical anomalies of Cu element in Malayer-Aligudarz-Esfahan metallogenic zone

Document Type : علمی -پژوهشی

Authors

1 Department of Petrolgy, Faculty of Geology, College of Science, University of Tehran, Tehran, Iran

2 Department of Geology, Faculty of Basic Sciences, Islamic Azad University, Ahwaz Branch, Ahwaz, Iran

Abstract

IntroductionMalayer-Aligudarz-Esfahan metal belt with a length of more than 400 km and a width of 90 km is located in the active zone of Sanandaj-Sirjan and is the largest lead and zinc metal belt in Iran. Considering that one of the most important metals with Pb and Zn zones is Cu, in this study, in order to separate geochemical anomalies from background anomaly of the Cu metal, we used fractal methods of concentration-area (C-A) and Singularity Index (SI).Materials and Methods MultifractalFractal and multifractal models have also been applied to separate anomalies from background values. These methods are gradually being adopted as an effective and efficient means to analyze spatial structures in metallic geochemical systems. The concentration-number (C-N), concentration-area (C-A) multifractal methods have been used for delineation and description of relations among mineralogical, geochemical and geological features based on surface and subsurface data. Fractal/multi-fractal models consist of the frequency distribution and the spatial self-similar or self-affine characteristics of geochemical variables and have been demonstrated to be effective tools for decomposing geological complexes and mixed geochemical populations and to recognize weak geochemical anomalies hidden within strong geochemical background.Singularity Index (SI)The Singularity technique is another important method developed for fractal/multifractal modeling of geochemical data. It is defined as the characterization of the anomalous behaviors of singular physical processes that often result in anomalous amounts of energy release or material accumulation within a narrow spatial–temporal interval. The Singularity can be estimated from observed element concentration within small neighborhoods based on the following equation:(1)The Singularity Index is a powerful tool to identify weak anomalies, but it is influenced by the selection of the window size.Results and Discussion                                              In general, 19974 stream sediment geochemical samples were analyzed using the ICP-MS and XRF method. The geochemical anomalies of the Cu metal were separated using fractal methods concentration-area (C-A) and according to the fitting line Cu metal on the logarithmic graph. The singularity index was estimated through a large window and mainly reflects regional changes but it does not focus on the local weak anomalies. In maps derived from fractal method of concentration-area (C-A), the North-West and South-East parts of the zone showed the highest anomaly. In maps that were obtained from the Singularity Index method, the hidden anomalies are better represented and there is a good overlap between the anomalies and the current position of the Cu deposits in the target zone.Conclusions      By matching the anomalies obtained from both methods with the geological map of the target area, it was determined that the obtained anomalies showed high overlap with the cretaceous limestone unit in the region. So this unit can be a good guide of exploration for identifying elements such as Pb, Zn and Cu in this area.

Keywords


  1. -قدیمی، ز.، 1394. استفاده از روش سینگولاریتی در تعیین آنومالی‌های ژئوشیمیایی منطقه خمین به کمک داده‌های رسوبات آبراهه‌ای. پایان‌نامه دوره کارشناسی‌ارشد، مهندسی معدن گرایش اکتشافات، دانشگاه صنعتی اراک.
  2. -قدیمی، ف.، قدیمی، ز. و قمی، م.، 1396. تعیین بی هنجاری‌های ژئوشیمیایی رسوبات آبراهه‌ای معدن سرب و روی سنگل شمال خمین با استفاده از روش شاخص سینگولاریتی، مجله یافته‌های نوین زمین‌شناسی کاربردی، شماره 11(22)، ص 119-131.‎
  3. -مغفوری، س.، حسین زاده، م.ر.، رجبی، ع. و عظیم زاده، ا.م.، 1396. کانسار دره زنجیر؛ نمونه‌ای از کانسارهای روی-سرب با میزبان کربناته (MVT) در توالی رسوبی کرتاسه پیشین، حوضه جنوب یزد، فصلنامه علمی-پژوهشی علوم زمین، شماره 26(103)، ص 13-28.‎
  4. -نظرپور، ا.، 1395. کاربرد مدل‌های فرکتال عیار-تعداد و عیار-مساحت در جداسازی آنومالی‌های ژئوشیمیایی در کانسار طلا زرشوران، شمال غرب ایران، مجله یافته‌های نوین زمین‌شناسی کاربردی، شماره 10(20)، ص 35-48.‎
  5.  
  6.  
  7. -Afzal, P., Mirzaei, M., Yousefi, M., Adib, A., Khalajmasoumi, M., Zarifi, A.Z. and Yasrebi, A.B., 2016. Delineation of geochemical anomalies based on stream sediment data utilizing fractal modeling and staged factor analysis, Journal of African Earth Sciences, v. 119, p. 139–149.
  8. -Agterberg, F.P., Cheng, Q., Brown, A. and Good, D., 1996. Multifractal modeling of fractures in the Lac du Bonnet batholith, Manitoba. Computers & Geosciences, v. 22(5), p. 497-507.
  9. -Agterberg, F.P., 2012. Multifractals and geostatistics, Journal of Geochemical Exploration, v. 122, p. 113-122.
  10. -Carranza, E.J.M., 2009. Controls on mineral deposit occurrence inferred from analysis of their spatial pattern and spatial association with geological features, Ore Geology Reviews, v. 35(3-4), p. 383-400.
  11. -Cheng, Q., Agterberg, F.P. and Ballantyne, S.B., 1994. The separation of geochemical anomalies from background by fractal methods, Journal of Geochemical Exploration, v. 51(2), p. 109-130.
  12. -Cheng, Q. and Agterberg, F.P., 1996. Multifractal modeling and spatial statistics, Mathematical Geology, v. 28(1), p. 1-16.
  13. -Cheng, Q., 2007. Mapping singularities with stream sediment geochemical data for prediction of undiscovered mineral deposits in Gejiu, Yunnan Province, China, Ore Geology Reviews, v. 32, p. 314-324.
  14. -Cheng, Q. and Zhao, P., 2011. Singularity theories and methods for characterizing mineralization processes and mapping geo-anomalies for mineral deposit prediction, Geoscience Frontiers, v. 2(1), p. 67-79.
  15. -Delavar, S.T., Afzal, P., Borg, G., Rasa, I., Lotfi, M. and Omran, N.R., 2012. Delineation of mineralization zones using concentration–volume fractal method in Pb–Zn carbonate hosted deposits, Journal of Geochemical Exploration, v. 118, p. 98-110.
  16. -Ehya, F., Lotfi, M. and Rasa, I., 2010. Emarat carbonate-hosted Zn–Pb deposit, Markazi Province, Iran: A geological, mineralogical and isotopic (S, Pb) study, Journal of Asian Earth Sciences, v. 37(2), p. 186-194.
  17. -Ghasemi, A. and Talbot, C.J., 2006. A new tectonic scenario for the Sanandaj–Sirjan Zone (Iran), Journal of Asian Earth Sciences, v. 26(6), p. 683-693.
  18. -Goncalves, M.A., Mateus, A. and Oliveira, V., 2001. Geochemical anomaly separation by multifractal modelling, Journal of Geochemical Exploration, v. 72(2), p. 91-114.
  19. -Hassanpour, S. and Afzal, P., 2013. Application of concentration–number (C–N) multifractal modeling for geochemical anomaly separation in Haftcheshmeh porphyry system, NW Iran, Arabian Journal of Geosciences, v. 6(3), p. 957-970.
  20. -Karimpour, M.H., Shafaroudi, A.M., Sevieri, A.E., Shabani, S. and Allaz, J.M., 2017. mineral chemistry, and ore-fluid conditions of Irankuh Pb-Zn mining district, south of Isfahan, Journal of Economic Geology, v. 9(2), p. 267-294.
  21. -Leach, D.L., Bradley, D., Lewchuk, M.T., Symons, D.T., de Marsily, G. and Brannon, J., 2001. Mississippi Valley-type lead–zinc deposits through geological time: implications from recent age-dating research. Mineralium Deposita, v. 36(8), p. 711-740.
  22. -Liu, Y., Zhou, K. and Cheng, Q., 2017. A new method for geochemical anomaly separation based on the distribution patterns of singularity indices, Computers & Geosciences, v. 105, p. 139-147.
  23. -Movahednia, M., Rastad, E., Rajabi, A. and Choulet, F., 2017. Mineralogy, geochemistry and genetic processes of supergene non-sulphide ore of the Ab-Bagh Sedimentary-Exhalative (SEDEX-type) Zn-Pb deposit, Sanandaj-Sirjan zone. p. 249-264.
  24. -Nazarpour, A., Sadeghi, B. and Sadeghi, M., 2015. Application of fractal models to characterization and evaluation of vertical distribution of geochemical data in Zarshuran gold deposit, NW Iran, Journal of Geochemical Exploration, v. 148, p. 60-70.
  25. -Nazarpour, A., Paydar, G.R. and Carranza, E.J.M., 2016. Stepwise regression for recognition of geochemical anomalies: Case study in Takab area, NW Iran, Journal of Geochemical Exploration, v.168, p. 150-162.
  26. -Rajabi, A., Rastad, E. and Canet, C., 2012. Metallogeny of Cretaceous carbonate-hosted Zn–Pb deposits of Iran: geotectonic setting and data integration for future mineral exploration. International Geology Review, v. 54(14), p. 1649-1672.
  27. -Rajabi, A., Rastad, E. and Canet, C., 2013. Metallogeny of Permian–Triassic carbonate-hosted Zn–Pb and F deposits of Iran: a review for future mineral exploration, Australian Journal of Earth Sciences, v. 60(2), p. 197-216.
  28. -Tan, Q.P., Wang, X., Xia, Y., Liu, Q. and Zhou, J., 2018. Identifying ore-related anomalies using singularity mapping of stream sediment geochemical data, a case study of Pb mineralization in the Qinling region, China, Geochemistry: Exploration, Environment, Analysis, v. 18(3), p. 177-184.
  29. -Shapiro, S.S. and Wilk, M.B., 1965. An analysis of variance test for normality (complete samples), Biometrika, v. 52(3/4), p. 591-611.
  30. -Wang, J. and Zuo, R., 2018. Identification of geochemical anomalies through combined sequential Gaussian simulation and grid-based local singularity analysis, Computers and geosciences, v. 118, p. 52-64.
  31. -Zuo, R., Cheng, Q., Agterberg, F.P. and Xia, Q., 2009. Application of singularity mapping technique to identify local anomalies using stream sediment geochemical data, a case study from Gangdese, Tibet, western China, Journal of Geochemical Exploration, v. 101(3), p. 225-235.
  32. -Zuo, R., 2014. Identification of weak geochemical anomalies using robust neighborhood statistics coupled with GIS in covered areas, Journal of Geochemical Exploration, v. 136, p. 93-101.
  33. -Zuo, R., Wang, J., Chen, G. and Yang, M., 2015. Identification of weak anomalies: A multifractal perspective, Journal of Geochemical Exploration, v. 148, p. 12-24.