استفاده از مدل‌ سازی فرکتالی برای پردازش و تحلیل مولفه‌ های ژئوالکتریک در مقاطع سطحی کانسار مس کوشک بهرام (ایران مرکزی)

کانسار مس کوشک بهرام واقع در شمال‌خاوری ساوه (ایران مرکزی)، بخشی از پهنه فرورانش ارومیه دختر است که بر اساس پیشینه‌های اکتشافی و شواهد زمین‌شناسی منطقه، به عنوان ذخیره سولفیدی نوع مانتو معرفی‌شده است. در این پژوهش که برای کاهش احتمال خطر سرمایه‌گذاری در فاز اکتشاف تفصیلی انجام‌شده است، ارتباط داده‌های ژئوفیزیکی با آثار سطحی کانه‌زایی، دگرسانی و گسل از دیدگاه فرکتالی بررسی و جدول‌های به دست آمده از برداشت سه پروفیل p1، p2 و p3، با استفاده از معادله پراش مسافت، بازخوانی و پردازش شده‌اند. در این روش، پس از شناسایی و تفکیک سطح توزیع براونی (fd>2)، امکان تدقیق و تلفیق کمیت‌های ژئوالکتریک فراهم‌شده است. نتایج پژوهش به تولید دو نقشه پیش‌داوری بر پایه توزیع فرکتالی مقاومت ویژه، بارپذیری الکتریکی و پتانسیل خودزا منجر‌شد که در آنها، مناطق امیدبخش معدنی با در نظر‌گرفتن مکان هندسی سطوح توزیع براونی rs ، ip و  spاولویت‌بندی شده‌اند. بازخورد توزیع فرکتالی کمیت‌های ژئوالکتریک در سطح اکتشافی کوشک بهرام متفاوت است؛ به طوری‌که در محدوده پروفیل‌های p1 و p2، مقاومت ویژه الکتریکی با تغییر بعد fd=2.78، به سطح آرمانی خود رسیده‌اند و سایر کمیت‌های ژئوالکتریک در شرایط مرزی هستند (بعد فرکتالی کوچک‌تر از 2 دارند). اما در محدوده پروفیل p3، شاهد خودسامان‌دهی کمیت بارپذیری الکتریکی در fd=2.06 هستیم و مقاومت ویژه الکتریکی، ویژگی‌های شبه فرکتالی دارد (fd=1.85).

Application of fractal modeling for processing and analysis of geoelectrical components in the Kushk-e-Bahram copper deposit (Central Iran)

IntroductionThe KushkeBahram Manto type copper deposit is located in the central Iran zone and   is UremiaDokhtar Magmatic Arc (UDMA) belt which includes copper porphyry deposits and related mineralization types, including the Manto type copper deposits (Jebeli et al., 2018a, b). Based on the type of mineralization and the presence of sulfides, high electrical conductivity (low electrical resistivity) can be detect in this deposit such as the Manto type deposits (Mehrnia, 2013., Mehrnia, 2016., Teymoorian Motlagh et al., 2012). On the other hand, Induced Polarization (IP) and electrical resistivity (RS) were used in the KushkeBahram deposit. Material and MethodsThe relationship between geoelectrical parameters and the mineralization process were recognized in geophysical assessments of the KushkeBahram de posit. It is necessary to obtain information about the shape and distribution of the orebody. According to exploratory data of the KushkeBahram deposit (Jebeli et al., 2018a, b), Cu mineralization has been extended. Therefore, the location and number of geoelectrical profiles were selected, based on previous studies which was generated in the ArcGIS software. The exchanges in the RS and IP values were measured, along three profiles (P1, P2, P3) and DipoleDipole arrangement with electrode distance of 10 meters. The device type used is WDJD3 and 1620 harvest points were surveyed. IP–RS profiles with azimuth 30 to 40 degrees were used in order to identify mineralization areas based on the highest variability of conductivity and loadbearing properties.  Moreover, they were designed and surveyed perpendicular to the mineralization process of the area. Considerations were taken into account based on the location of trenches and the mineralization sequence of this area. The P1 and P2 profiles with an approximate length of one kilometer and P3 profile with an approximate length of 370 m were designed and harvested under a 30 degree azimuth. Results and DiscussionIn this research study, a number of geoelectrical sections were selected and their surface changes in a twodimensional environment were refined and internalized by the algorithm used in the diffractiondistance distribution function. According to the position of P1 and P2 profiles, all three quantities of RS, IP and selfPotential have been interpolated to match the alteration zones and faults of the study area in the P3. The quantity of Spontaneous Potential (SP) is not measured and it just suffices to internalize specific electrical changes and IP and their conformity with the effects of alteration and faults in the region. Interpolation of geoelectrical data by the inverse distance weighting estimation method and nearest neighborhood algorithms were carried out (Mehrnia, 2016; Teymoorian Motlagh et al., 2012).Based on the fractal dimension, four targets around the P1 and P2 profiles and eight priorities have been identified around the P3 profile. Based on the results, geoelectrical data distribution pattern was obtained using diffractiondistance model and changes in the fractal dimension of electrical resistivity, induced polarization and selfgenerating electric potential according to the differences of the fractal dimensions for IP, RS and SP in the KushkeBahram deposit. It is necessary to interpret geoelectrical sections based on fractal dimension exchanges to avoid the oblique error caused by the fitting of disproportionate quantities as much as possible. Consequently, exchanges in the level of electrical resistivity and induced polarization were calculated. There is no corresponding trend along P1 and P2 profiles. Thus, the results of the diffractiondistance model were correlated with mineralization potential in the depth of the deposit. Continuation of exploration activities (detailed phase) along the P1, P2 and P3 profiles are suggested. Based on inferring from the  Brownian mechanism distribution of electrical resistivity quantities and inductive polarization, priority of P1 and P2 profiles with vein and disseminated mineralization in P3 profile is obtained. ReferencesJebeli, M., Afzal, P., Pourkermani, M. and Jafarirad, A., 2018a. Correlation between rock types and Copper mineralization using fractal modeling in KushkeBahram deposit, Central Iran. Geopersia, 8(1): 131–141. https://dx.doi.org/10.22059/geope.2017.237332.648334Jebeli, M., Kheyrollahi, H. and Afzal, P., 2018b. Exploration and Interpretation Geophysical using of IP and RS Data in KushkeBahram Manto Copper deposit, NE Saveh. The 21 Symposium of Geological Society of iran, Geological society of iran, Ghom. Iran.Mehrnia, S.R., 2013. Application of fractal geometry for recognizing the pattern of textural zoning in epithermal deposits: (case study: Shikhdarabad AuCu indices EastAzerbaijan province). Journal of Economic Geology, 5(1): 23–36. (in Persian with English abstract) https://dx.doi.org/10.22067/econg.v5i1.22885Mehrnia, S.‌R., 2016. Application of Fractal Technique for Analysis of Geophysical Geochemical Databases in Tekieh PbZn Ore Deposit (SE of Arak), Journal of Economic Geology, 8(2): 325–342. (in Persian with English abstract) https://dx.doi.org/10.22067/econg.v8i2.42454Teymoorian Motlagh, A., Ebrahimzadeh Ardestani, V., Mehrnia, S.‌R., 2012. Fractal method for determining the density of the stone tablet in Charak region (southern Iran). Life Science Journal, 9(4): 1913–1923. Retrieved April 01, 2021 from http://www.lifesciencesite.com