Three-dimensional analysis of aeromagnetic and gravimetric data of sedimentary basins from Panama, Central America

Abstract: The knowledge of the geology of the sedimentary basins from the Gulf of Panama is still quite limited. There is a lack of data from the basin geometry, the thickness, the continuity and connection between the basins, and from the characteristics of the crystalline basement rocks beneath the sedimentary basins. Geological maps have been published without evidence from geophysical studies; i.e. marine faults patters are showed only as the continuation of fault pattern on land and in some cases faults are showed only to adjust geodynamics models. In the marines areas the geophysical surveys so far carried out, like seismic reflection and well logging, have not given information about the nature of and depth to the crystalline basement rock and interpretations of aeromagnetic and gravity data are still missing. Many of the geophysical surveys like aeromagnetic and marine gravity data have been published as contour maps. However, different data processing techniques and various references levels have been used, which do not permit an integral regional analysis. Here we present composite regional aeromagnetic and gravity maps and integral interpretations with reference to source parameters such as; depths to the top of basement rock, faults patters, locations of magnetic boundaries, susceptibility contrasts, geometry and connection between the basins. The interpretations are based on regional aeromagnetic maps and on marine and land gravity data compiled from several sources and integrated with reference to a fixed level. Various techniques have been applied for the interpretation e.g. enhancement of the aeromagnetic anomalies maps by sun shading technique, applying band pass filtering and upward analytic continuation. Maps have also been transformed into images called 3D analytic signal amplitude and local wave number maps. The depth estimates resulting from the analyses of these maps are compared and the location of interpreted contacts are combined into a map showing the dip direction for contacts. The Bouguer gravity data from the Gulf of Panama are transformed into a residual anomaly map using a filtering technique. This residual anomaly map have been analyzed in order to estimate depths to the top of the basement rocks.