بهبود روش آمارۀ فضایی U با مدل‌سازی شاخص غنی‌شدگی عناصر رسوبات آبراهه‌ای به هدف معرفی مناطق آنومال ژئوشیمیایی کانی‌سازی تیپ طلای اپی‌ترمال

نوع مقاله : علمی - پژوهشی

نویسندگان

1 استادیار دانشگاه محقق‌اردبیلی، دانشکدۀ فنی و مهندسی

2 کارشناس ارشد زمین شناسی اقتصادی، دانشگاه محقق اردبیلی

3 استادیار دانشگاه محقق اردبیلی، گروه زمین‌شناسی، دانشکدۀ علوم

چکیده

هاله‌های ژئوشیمیایی مناطقی در اطراف ذخایر معدنی‌اند که در آن غلظت عناصر تا حد ثابتی به نام زمینه کاهش می‌یابد. در این میان برای پی بردن به غلظت غیرعادی عناصر یعنی آنومالی باید حد فوقانی مقدار زمینه یعنی حدآستانه‌ای تعیین شود. برای رسیدن به این هدف استفاده از روش‌های نوین و جدید اکتشافی موثر و کارآمد است. در این مقاله برای ترسیم مناطق پتانسیل‌دار رسوبات آبراهه‌ای از روش مدل‌سازی داده‌های شاخص غنی‌شدگی عناصر با روش آماره فضایی U استفاده شده است. با توجه به ویژگی‌های مورفولوژی محیط رسوبات آبراهه‌ای، منشا نمونه‌های برداشت شده از این رسوبات به بالادست حوضه‌های آبریز برمی‌گردد، بنابراین تحلیل داده‌های ژئوشیمیایی این نمونه‌ها با محیط‌های سنگی از این لحاظ متفاوت است و باید یک مدل‌سازی اولیه بر روی داده‌ها برای درنظر گرفتن ویژگی‌های زمین‌شناسی بالادست نمونه‌ها انجام گیرد. ماهیت همسانگردی پنجره‌ای که میانگین‌گیری وزنی در الگوریتم روش آماره فضایی U انجام می‌شود، طوری است که تمامی نمونه‌های بالاست و پایین‌دست نمونه‌ها در این میانگین‌گیری سهیم‌اند و این مورد می‌تواند نقطه ضعف قابل توجهی برای این روش به شمار آید. برای کاهش این ضعف و در جهت بهبود روش، ابتدا با در نظر گرفتن واحدهای سنگی بالادست، بر روی داده‌های خام، شاخص غنی‌شدگی عناصر بدست آمد و سپس مدل‌سازی آماره U بر روی این شاخص‌ها انجام شد. با این روش، ضمن اینکه اندیس‌های منطقه با دقت بیشتری شناسایی شدند، مناطق پتانسیل‌دار کاذب بدست آمده از روش آماره فضایی U نیز حذف شده و نتایج قابل قبول و نزدیک به واقعیت‌های میدانی برای تعیین مناطق پتانسیل‌دار کانی‌سازی نمایان شد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Improving the method of U-spatial statistics by modeling the enrichment index of stream sediments for the purpose of introducing geochemical anomalous areas of epithermal gold type mineralization

نویسندگان [English]

  • Mirmahdi Seyedrahimi-Niaraq 1
  • Neda Shokri 2
  • Ali Lotfibakhsh 3
1 University of Mohaghegh Ardabili, Ardabil, Iran
2 University of Moheghegh Ardabili
3 University of Mohaghegh Ardabili
چکیده [English]

Geochemical halos are regions around mineral deposits where the concentration of elements decreases to a constant level called the background. In the meantime, in order to find out the unusual concentration of elements (anomaly), the upper limit of the background limit (threshold value), must be determined. To achieve this goal, it will be effective and efficient to use new exploration methods. In this article, to draw the potential areas of stream sediments, modeling the data of element enrichment index with the U-spatial statistic method has been used. According to the morphological characteristics of the stream sediments environment, the origin of the samples taken from these sediments goes back to the upstream of the watersheds, so the analysis of the geochemical data of these samples is different from the rock environments. A preliminary modeling should be done on the data to consider the geological features upstream of the samples. The isotropic nature of the window in which the weighted averaging is performed in the algorithm of the U-spatial statistics method is such that all the upstream and downstream samples participate in this averaging and this case can be the point considered a significant weakness for this method. To reduce this weakness and to improve the method, first by considering the upstream rock units, the element enrichment index was obtained on the raw data, and then the U statistics was modeled on these indices. With this method, while the indices of the area were more accurately identified, the false potential areas obtained from the U-spatial statistic method were also removed and the results were acceptable and close to the field realities for determining mineralization potential areas.

کلیدواژه‌ها [English]

  • Enrichment index data modeling
  • U-spatial statistic method
  • Geochemical anomaly
  • Epithermal type gold
  • Khoshnameh region
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