جداسازي آنومالي‌هاي زمين‌شيميايي فلزات سرب و روي با استفاده از روش‌ آماري كلاسيك (Mean+nSTEV)، شاخص سينگولاريتي، سنجش از دور و عوامل ساختاري در ورقه 1:100000 خُنداب؛ بخش شمالي زون ملاير-اليگودرز-اصفهان

Discrimination of geochemical anomalies of Pb and Zn metals using the classical statistical (Mean+nSTEV), Singularity Index, remote sensing and structural factors method in Khondab 1:100000 sheet, northern part of the Malayer-Aligoudarz-Esfahan zone

ورﻗﻪ زﻣﯿﻦﺷﻨﺎﺳﯽ 1:100000 ﺧﻨﺪاب در ﻗﺴﻤﺖ ﺷﻤﺎﻟﯽ ﮐﻤﺮﺑﻨﺪ ﻓﻠﺰزاﯾﯽ ﻣﻼﯾﺮ-اﻟﯿﮕﻮدرز-اﺻﻔﻬﺎن ﯾﮑﯽ از ﺑﺎ ﭘﺘﺎﻧﺴﯿﻞﺗﺮﯾﻦ ورﻗﻪﻫﺎي ﻣﻮﺟﻮد در ﮐﺸﻮر ﺑﺮاي ﺗﺸﮑﯿﻞ ﮐﺎﻧﺴﺎرﻫﺎي ﺳﺮب و روي ﻣﯽﺑﺎﺷﺪ. در اﯾﻦ ﻣﻄﺎﻟﻌﻪ از روش آﻣﺎر ﮐﻼﺳﯿﮏ، ﺷﺎﺧﺺ ﺳﯿﻨﮕﻮﻻرﯾﺘﯽ، ﺳﻨﺠﺶ از دور، ﻧﻤﻮدار ﺷﻮاﻫﺪ وزﻧﯽ )WofE( و ﺗﺠﺰﯾﻪ و ﺗﺤﻠﯿﻞ ﺳﺎﺧﺘﺎري ﺑﺮاي ﺟﺪاﺳﺎزي آﻧﻮﻣﺎﻟﯽﻫﺎي ژﺋﻮﺷﯿﻤﯿﺎﯾﯽ از زﻣﯿﻨﻪ ﺑﺮاي ﻓﻠﺰات ﺳﺮب و روي در ﻣﻨﻄﻘﻪ ﻣﻮرد ﻣﻄﺎﻟﻌﻪ ﺑﮑﺎر ﮔﺮﻓﺘﻪ ﺷﺪ. ﺑﻪ ﻃﻮر ﮐﻠﯽ در ﻣﺠﻤﻮع از 2006 ﻧﻤﻮﻧﻪ ژﺋﻮﺷﯿﻤﯿﺎﯾﯽ از رﺳﻮﺑﺎت آﺑﺮاﻫﻪاي ﮐﻪ ﺗﻮﺳﻂ روش ICP-MS ﻣﻮرد ﺗﺠﺰﯾﻪ و ﺗﺤﻠﯿﻞ ﻗﺮار ﮔﺮﻓﺘﻪ اﺳﺘﻔﺎده ﺷﺪه اﺳﺖ. روش آﻣﺎر ﮐﻼﺳﯿﮏ Mean+nSTEV)( ﻧﺸﺎن ﻣﯽدﻫﺪ ﮐﻪ ﻣﻘﺎدﯾﺮ آﺳﺘﺎﻧﻪ ﺑﺮاي ﻓﻠﺰات ﺳﺮب و روي ﺑﻪ ﺗﺮﺗﯿﺐ 30/75 ppm و 153/18 ppm اﺳﺖ. در ﻧﻘﺸﻪﻫﺎي ﺑﺪﺳﺖ آﻣﺪه از روش ﺷﺎﺧﺺ ﺳﯿﻨﮕﻮﻻرﯾﺘﯽ SI)( آﻧﻮﻣﺎﻟﯽﻫﺎي ﺿﻌﯿﻒ و ﭘﻨﻬﺎن ﺑﻬﺘﺮ ﻧﻤﺎﯾﺶ داده ﺷﺪه و ﻫﻤﭙﻮﺷﺎﻧﯽ ﺑﻬﺘﺮي ﺑﺎ ﺳﻨﮓ آﻫﮏ ﺑﻪ ﻋﻨﻮان ﺳﻨﮓ ﻣﯿﺰﺑﺎن در ذﺧﺎﯾﺮ ﺳﺮب و روي )ﻧﻮع MVT(، ﺗﺮاﮐﻢ ﮔﺴﻞﻫﺎ و دﮔﺮﺳﺎﻧﯽﻫﺎي ﻣﻮﺟﻮد در ﻣﻨﻄﻘﻪ ﻣﻮرد ﻣﻄﺎﻟﻌﻪ، ﻧﺸﺎن ﻣﯽدﻫﺪ. ﻋﻼوه ﺑﺮ اﯾﻦ، آﻧﻮﻣﺎﻟﯽﻫﺎي ﺑﺪﺳﺖ آﻣﺪه از اﯾﻦ روش ﻫﻤﭙﻮﺷﺎﻧﯽ ﺑﺎﻻﯾﯽ ﺑﺎ ﮐﺎﻧﺴﺎرﻫﺎ و ﻣﻌﺎدن ﺳﺮب و روي ﻣﻮﺟﻮد در ﻣﻨﻄﻘﻪ ﻧﺸﺎن ﻣﯽدﻫﻨﺪ. ﺑﻄﻮر ﮐﻠﯽ در اﯾﻦ ﻣﻄﺎﻟﻌﻪ ﻣﺸﺨﺺ ﮔﺮدﯾﺪ ﮐﻪ ﻋﯿﺎر ﻓﻠﺰ ﺳﺮب در ﺟﻨﻮب و ﺷﻤﺎلﺷﺮق و ﻋﯿﺎر ﻓﻠﺰ روي در ﺷﻤﺎلﺷﺮق و ﻣﺮﮐﺰ ﻣﺤﺪوده ﺑﯿﺸﺘﺮﯾﻦ ﻣﯿﺰان آﻧﻮﻣﺎﻟﯽ را از ﺧﻮد ﻧﺸﺎن ﻣﯽدﻫﻨﺪ ﮐﻪ در اﯾﻦ ﻣﻨﺎﻃﻖ اﺣﺘﻤﺎل وﺟﻮد ﻣﻨﺎﻃﻖ ﮐﺎﻧﺴﺎري از ﻧﻮع MVT ﺑﺴﯿﺎر ﺑﺎﻻ اﺳﺖ. از ﻃﺮﻓﯽ آﻧﻮﻣﺎﻟﯽﻫﺎي ﺑﺪﺳﺖ آﻣﺪه ﺑﺎ واﺣﺪﻫﺎي آﻫﮏ ﮐﺮﺗﺎﺳﻪ و ﮔﺴﻠﺶ ﻣﻨﻄﻘﻪ ﮐﻪ در ﮐﺎﻧﻪزاﯾﯽ ﺳﺮب و روي ارﺗﺒﺎط ﻣﺴﺘﻘﯿﻤﯽ دارد، اﻧﻄﺒﺎق ﺑﺎﻻﯾﯽ را ﻧﺸﺎن ﻣﯽدﻫﻨﺪ.

Separation of geochemical anomalies from background has always been a major concern in geochemical exploration (Nazarpour, 2018. The Malayer-Aligudarz-Isfahan metallogenic belt with the north-west-south-east trend is the largest and most important Pb-Zn belt of MVT type in Iran (Rajabi et al., 2012). Khondob 1:100000 geological sheet as a high potential area is located in the north of Malayer-Aligoudarz-Efsahan Pb-Zn metalogenic belt. Various statistical methods have been used to process geochemical data in order to determine threshold values. In this study, classic statistical Mean+2SDEV), Singularity Index (SI) analysis, remote sensing, weight of evidence (WofE) and structural analysis methods, have been applied to separate geochemical anomalies from background of the Pb and Zn metals in the study area. 2-Methodology 2-1-Classical statistics Statistical quantities, such as the mean, standard deviation (SDEV) and percentiles, have been used to define threshold for separating anomalies form background. For example, geochemical anomalies have been defined as values greater than a threshold defined as the 75th or 85th percentile, and Mean+SDEV or Mean+2SDEV (Nazarpour et al., 2015). 2-2- Singularity Index The singularity technique is another important progress for fractal/multifractal modeling of geochemical data (Zuo et al., 2012). 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 (Cheng, 2007