Interpretation of aeromagnetic data for detection of magnetic basement and concealed faults in Basiran area, south of khorasan
Subject Areas :Mohammad Mohammadzadeh 1 , GholamAbbas Fanaee Kheirabad 2 , Saba Moradalivand 3 , mahbobe abedisamakosh 4
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Keywords: Basiran area South of Khorasan, Magnetic basement Magnetic lineaments, Aeromagnetic.,
Abstract :
Basiran area in the south of Birjand city is well-known for its important mineral potential and is located in the volcanic region of eastern Iran. . In 2005, the geological survey of Iran (GSI) conducted a high resolution airborne magnetic survey over the area about 850 km2 to create a suitable geospatial database for further explorations and investigations. Aeromagnetic survey is an effective tool for magnetic basement mapping and detecting concealed magnetic lineaments in a volcanic area. This work focuses on two main subjects using aeromagnetic data: (1) depth estimation of sediment sequences (i.e. depth to the magnetic basement), and (2) extracting magnetic lineaments. Necessary corrections such as diurnal, compensation, lag and IGRF applied over the raw aeromagnetic data to generate residual magnetic intensity data. Then, required filters were sequentially applied. They were reduced-to-pole (RTP), upward continuation (UP), Euler and Werner deconvolutions and Tilt derivation (TDR). To estimate the thickness of sedimentary sequences, a combination of depth estimators that were the Euler and Werner were utilized. Consequently, the outputs showed thick volcanic (magnetic basement) outcrops in some portions, and the thick sedimentary sequences that extended from a depth of a few meters to 1200 meters. Magnetic lineament in the form of magnetic fabric and fault were detected by tilt derivation method, in which positive and negative peaks in TDR map were in association with a magnetic fabric in the area. Meanwhile, magnetic fabrics showed small linear magnetic traces which were used for recognition of linear structural pattern. In addition, magnetic faults were detected through implementation of a collection of filters namely TDR of RTP_UP of 50, 200, 500 and 1000 meters. Note that, minor magnetic faults (order 1) were only detectable in the low level TDR_UP, but major ones were detectable in the high level of TDR_UP. This work emphasizes the important role of the magnetic data processing to better understand the relation between magnetic anomalies and the subsurface geology. Totally, more than 20 first and second order faults were identified and mapped
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