Geophysical Surveys Database
Airborne regional magnetic surveys cover outcropping Precambrian rocks in the western part of Saudi Arabia (the Arabian Shield), Phanerozoic sedimentary rocks east and north of the shield (the “Cover rocks”), and parts of the Red Sea basin.
The measured Total Magnetic Intensity (TMI) potential field data of the surveyed area are presented as pseudo-color raster map from contour map. The main purpose of the magnetic surveys is to establish the tectonics of an area, which help in geological mapping. In order to remove the inclination effects from the measured aeromagnetic data and to simplify the anomaly shapes, the TMI data are Reduced to the Pole (RTP). The reduction to the pole aims to reduce the anomalies to those that would be observed at the magnetic North pole, where the magnetic inclination is vertical.
The RTP FVD is the First Vertical Derivative of the RTP grid. This technique is routinely computed from the data to enhance local anomalies in a map and to help outlining the edges of anomalous bodies from the data. It is a powerful interpretive tool which can be used to assist in the delineation of causative bodies and accurate location of changes in the potential field’s gradients. Better definition of discontinuities and their relation to geology can be gained from the use of this tool.
The (ANSIG) is the Analytic Signal or total derivative of the RTP grid which is used in locating the magnetic sources. The analytical signal of the total magnetic field reduces the magnetic data to anomalies whose maxima mark the edges of the magnetized bodies.
The original data coordinates are Lambert Cartesian (LCC), with standard parallels of 17 and 33 degrees N and a central meridian of 48 degrees E, and no false northing or easting. The grid interval (cell size) is 200 m.
- Analytic Signal (Reduced to the pole map) - Unit: nt nanotesla
- Total magnetic intensity map - Unit: nt nanotesla
- Reduced to the Pole map
- First vertical derivative, reduced to the Pole map
- Gravity Anomaly (Pierre Bouguer) - Unit: milligal (mGal)