عنوان مقاله :
مقايسه روش فركتال عيار-مساحت (C-A) و شاخص سينگولاريتي در جداسازي آنوماليهاي ژئوشيميايي عنصر مس در زون فلززايي ملاير-اليگودرز-اصفهان
عنوان به زبان ديگر :
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
پديد آورندگان :
جعفري، محمدامين پرديس علوم دانشگاه تهران - دانشكده زمين شناسي - گروه پترولوژي , كنعانيان, علي پرديس علوم دانشگاه تهران - دانشكده زمين شناسي - گروه پترولوژي , نظرپور, احد دانشگاه آزاد اسلامي واحد اهواز - دانشكده علوم پايه - گروه زمين شناسي
كليدواژه :
فركتال , عيار مساحت , شاخص سينگولاريتي , مس , ملاير اليگودرز اصفهان
چكيده فارسي :
كمربند فلززايي ملاير-اليگودرز-اصفهان با طولي افزون بر 400 كيلومتر و عرض 90 كيلومتر بزرگترين كمربند فلززايي سرب و روي در ايران است. با توجه به اينكه يكي از مهم ترين فلزات همراه با زون هاي سرب و روي، مس مي باشد، در اين پژوهش، به منظور جدايش جوامع آنومالي ژيوشيميايي از زمينه اين فلز از روش هاي فركتال عيار- مساحت (C-A) و شاخص سينگولاريتي (SI) استفاده شده است. لذا تجزيه و تحليل 19974 نمونه از رسوبات آبراهه اي با استفاده از روش هاي نام برده در زون فلززايي ملاير- اليگودرز- اصفهان، منجر به تفكيك مناطق آنومال عنصر مس گرديد. در نقشه هاي حاصل از مدل فركتال عيار- مساحت (C-A)، قسمت هاي شمال غرب و جنوب شرق زون بيشترين ميزان آنومالي را از خود نشان مي دهد. در نقشه هاي حاصل از روش شاخص سينگولاريتي (SI)، آنومالي هاي پنهان بهتر نمايش داده شده و انطباق خوبي بين آنومالي ها و موقعيت فعلي معادن مس در زون مورد نظر وجود دارد. با تطبيق آنومالي هاي به دست آمده از هر دو روش با نقشه زمين شناسي محدوده مورد نظر، مشخص گرديد كه آنومالي هاي به دست آمده هم پوشاني بالايي با واحد آهك كرتاسه در منطقه نشان مي دهد و لذا اين واحد مي تواند راهنماي اكتشافي مناسبي براي پي جويي عناصري نظير سرب، روي و مس در اين منطقه محسوب شود.
چكيده لاتين :
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.
عنوان نشريه :
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