Investigating Secondary Dispersion Patterns of Indicator Minerals Using Gis

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Picturing the Subsurface With GIS: Data Visualization Techniques for Geophysical Images Using ArcGIS By Lucas Donny Setijadji Geoscientists try to understand the earth's crust using geophysical methods such as gravity and magnetic surveys. Mining geologists also use geophysics to search new mineral deposits. In areas such as the Nevada Great Basin, geoscientists rely more on geophysical images than on geologic maps. The Great Basin area holds one of the biggest mineral concentrations in the world. Economically, gold is the most prominent commodity. The most important gold deposits are hosted by carbonate rocks, called the Carlin-type and Carlin-like gold deposits. Carlin-type and Carlin-like gold deposits are unique geologically,…show more content…
The goal is to separate the regional trends and residual anomalies. The digital separation processes sometimes involve the transformation of data from the space domain into the wave–number (Fourier) domain. This filtering process requires specific geophysical software such as the MAGMAP product from Oasis Montaj©. The filtering algorithm applied to the gravity map was a band-pass filter to find intermediatewavelength gravity anomalies. These anomalies represent deep-seated geologic units and structural configurations (Figure 2). Meanwhile, the upward continuation filter for 1 km was applied on the aeromagnetic map to eliminate the noise from shallow magnetic sources. The result represents magnetic bodies at a significant depth below the surface (Figure 3). Figure 2—The IntermediateWavelength Gravity Anomaly Map After Application of Band-Pass Filtering Figure 3—The Magnetic Anomaly Map After the Application of 1 km Upward Continuation Filtering Data Integration With GIS and Some Concerns Geophysical processing software usually lacks GIS functionality. Spatial analysis is much easier when done in a GIS environment. Transformation of geophysical images to a GIS format can be as simple as exporting the images that contain spatial information into geoTIFF format. In a GIS analysis, geophysical images are often treated as a type of evidence map, the same as other thematic maps such as mineral

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