مجله ژئوفیزیک ایران

مجله ژئوفیزیک ایران

شناسایی زون‌های کانی‌سازی مس-طلای پورفیری با استفاده از داده‌های مغناطیس هوایی، مطالعه موردی محدوده مطالعاتی بریتیش کلمبیا، کشور کانادا

نوع مقاله : مقاله پژوهشی‌

نویسندگان
1 دانشجوی دکتری اکتشاف معدن، دانشگاه صنعتی امیرکبیر، تهران، ایران
2 استاد، گروه مهندسی اکتشاف معدن، دانشگاه صنعتی امیرکبیر، تهران، ایران
چکیده
داده‌های مغناطیس هوایی در محدوده بریتانیا کلمبیا در کشور کانادا برای تفسیر و استخراج خطواره‌ها و ساختارهای زمین‌شناسی استفاده شده است. در این مقاله از روش اتوماتیک برای استخراج ساختارها استفاده گردیده است. محدوده مطالعاتی در کشور کانادا قرار دارد و به لحاظ کانی‌سازی مس- طلای پورفیری حائر اهمیت می‌باشد. برای استخراج ساختارها و نفوذی‌های پورفیری از مرکز هدف گزاری اکتشافی (CET) نرم‌افزار ژئوسافت استفاده شده است. با استفاده از این روش ابتدا واحدهای پورفیری موجود در محدوده مورد مطالعه و به کمک نقشه برگردان به‌قطب استخراج گردید. سپس ساختارهای سطحی با استفاده از نقشه مشتق قائم مرتبه اول استخراج گردید و نقشه ساختارهای خطی محدوده مورد مطالعه با استفاده از روش اتوماتیک استخراج شد. نتایج نشان می‌دهد که ساختارها در محدوده مورد مطالعه عمدتاً روند شمال غرب- جنوب شرق دارند ولی بعضاً ساختارهایی با روند شمالی- جنوبی، شرقی غربی و شمال شرق- جنوب غرب نیز در محدوده مشاهده می‌شوند. نواحی با چگالی بالای خطواره‌های مغناطیسی منطبق با اندیس‌های مس پورفیری موجود در محدوده مطالعاتی می‌باشند تطابق اندیس‌های مس پورفیری با ساختارهای مغناطیس نقش موثر گسل‌ها را در تشکیل کانسارهای مس پورفیری را تایید می‌کند.
کلیدواژه‌ها

موضوعات


عنوان مقاله English

Identification of copper-gold porphyry mineralization zones using airborne magnetic data, a case study of the British Columbia study area, Canada

نویسندگان English

Moslem Jahantigh 1
Hamid Reza Ramazi 2
1 Ph.D. Student in Mineral Exploration, Amir Kabir University, Tehran, Iran
2 Professor, Mineral Exploration Group, Amir Kabir University, Tehran, Iran
چکیده English

The study area are located in British Coloumbia in Canada. This area consist of numerous cu- Au porphyry indication. Most of studied area is covered with sedimentary rocks. Igneous rocks caused caused metamorphosis in sedimentary rocks. Igneous rocks were intruded along faults. The most of volcanic rocks include of basalt and volcano sediments. The ignous rocks in the study area include of gabbro, diorite, volcanic rocks, ultramafic roks and…Airborne magnetic data have been used in British Columbia in Canada to interpret and extract lineaments and geological structures. Aeromagnetic method is a well known method to extract geological formation and structures. Different filter can be applied on aeromagnetic data to extract geological information. For example tilt angle method can be used to extract linear structures. First vertical derivative can be used to extract near surface structures and bodies. CET grid analysis is useful tool to extract lineaments automatically. This method distinguishes alteration zone in porphyry mineralization very well. The high alteration zones can be related to potassic alteration and igneous rocks and low ateration can be relate to phyllic alteration. In this article, the automatic method is used to extract the structures. Then reduction to pole transformation was done on total magnetic intensity map. Reduction to the pole (RTP) is a standard part of magnetic data processing method, especially for large-scale mapping. RTP operation can transform a magnetic anomaly caused by an arbitrary source into the anomaly that the same source would produce if it is located at the pole and magnetized by induction only. The study area is located in Canada and it is important in terms of copper-gold mineralization of Haer porphyry. Geosoft software was used to extract porphyry structures and intrusions from the Ecntre of Exploration Targeting(CET). High magnetic anomalies were extracted as porphyry intrusion from reduction to pole map and with automatic method. High magnetic anomalies in first vertical derivative were extracted as near surface structure. Lineament structures were extracted with automat method and with CET grid analysis menu in Geosoft software. The results show that the structures in the studied area mainly have a northwest-southeast trend, but sometimes structures with a north-south, east-west and northeast-southwest trend are also observed in the area. The areas with high density of magnetic lines are consistent with porphyry copper indices in the study area. The matching of porphyry copper indices with magnetic structures confirms the effective role of faults in the formation of porphyry copper deposits.

کلیدواژه‌ها English

Porphyry
centre of exploration targeting
British Collumbia
aermagnetic data
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