Subsurface Geology and Geologic Structure of the Euiseong Basin using Gravity, Magnetic, and Satellite Image Data

Euiseong subbasin, included in the Kyungsang Basin, was created by the result of volcanic activity in the late Cretaceous, and contacts with Milyang and Youngyang subbasins by Palgongsan and Andong faults, respectively. In this study, geophysical survey is implemented for investigating surface and subsurface geologic structure in Euiseong subbasin which composed with the complex of volcanic and plutonic rocks. To understand surface geologic feature, IRS satellite image and DEM(Digital Terrain Map) are used for analyzing lineament and its density. The numbers of lineaments show major trend in N55 degrees similar to 65 degrees W, and aspects of lineament lengths show major trend in N55 degrees similar to 65 degrees W and N-S directions. To delineate subsurface density discontinuity, power spectrum analysis was implemented for gravity anomaly data, resulting 4-5 km depth of basin basement and 0.5-0.6 km depth of shallow discontinuity. From the result of power spectrum analysis, 2.5-D modelings were implemented along two profiles of A-A and B-B', and they show subsurface geology in detail. Analytic signal method for detecting boundaries of magnetic basements show 0.001-130 nT/m values, and high energy area show good correspondency with the boundaries of Palgongsan granite and caldera areas in Euiseong subbasin.