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| IRON EXPLORATION USING AEROMAGNETICS |
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| A client requested for an aeromagnetic survey to pin down an area to focus an exploration program for iron ore and to verify the occurrence of magnetite mineralization within the survey area. Elliott Geophysics International conducted the aeromagnetic (helimag) survey on year 2008 on an island in Sulawesi, Indonesia. The survey aims to locate discrete or short length magnetic anomalies that may represent hydrothermal magnetite deposits. |
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| A Bell-206B helicopter was flown for the survey. Geometrics G823A Cesium Vapour Magnetometer with a resolution of 0.001 nT, and a cycle rate of 0.1 second was used for data acquisition. The effective noise envelope was generally less than +/- 0.02nT. Real time differential GPS satellite information was obtained from an Omnistar 3200L GPS in conjunction with the Omnistar satellite system (remote regional base station link). |
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| A Honeywell KRA10A radar altimeter was installed under the helicopter and readings were recorded every 0.1 second. A barometric altimeter installed in the front panel of the aircraft assisted the pilot with height verification and helped with calibration of the radar altimeter. G856 Proton Precession Magnetometers were placed near the helipad and used as base station magnetometers. |
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| Reduce to Pole (RTP) images, Digital Elevation Model and Stacked Profiles were used for the interpretation of survey data. Portion of the RTP image (Figure 1) shows the main anomaly which is a sub-circular feature consisting of several high amplitude responses. This main target of magnetization is possibly due to the emplacement of an intrusive of sub-volcanic origin (probably granite) within the host rock (possibly sedimentary or metamorphic) and or maybe a structure controlled by a hydrothermal system. The low magnetic response surrounding this anomaly could be due to the alteration of the magnetite by continuous hydrothermal activity. |
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| Figure 2 shows the geology of the area as interpreted from the aeromagnetic data. The highlighted area should be checked for iron and/or magnetite mineralization. Geologic mapping and sampling are suggested to verify the occurrence of iron. It is also recommended to conduct follow-up detailed ground magnetic and deep penetrating IP surveys for areas for a possible presence of deep porphyry-style mineralization. |
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