Interpreting structural configuration of the Sengkang Basin of Indonesia using edge detection and 3-D Euler deconvolution to satellite gravity data

Authors: JAMHIR SAFANI, KHALIL IBRAHIM, WA DENI, AL RUBAIYN, FIRDAUS FIRDAUS, HARISMA HARISMA

Abstract: The East Walanae Fault Zone and the West Walanae Fault Zone are the two active fault segments in the south arm of Sulawesi. These fault segments are responsible for the formation of the Sengkang Basin. This geological complexity makes the Sengkang Basin a very interesting area to study. This research aims to (1) identify basin boundaries and lithological contacts; (2) estimate the positions of fault segments; and (3) model the basement beneath the Sengkang Basin. The free-air gravity anomaly from the GGMPlus dataset is employed and then corrected using Bouguer and terrain corrections to provide the complete Bouguer gravity anomaly (CBA). Polynomial surface fitting is used to separate the residual gravity data from the CBA. Nine edge detection filters are employed to identify structural configuration (i.e. basin boundaries, lithological contacts, and fault segments). The Euler deconvolution is utilized to describe the geological structure and estimate its depth. The radially average power spectrum and inversion of the residual gravity anomaly data are applied to analyze the basement of the study area. The results of the analysis show the superiority of the horizontal gradient of tilt angle (HGTA) technique in identifying basin boundaries and lithological contacts. Three new subbasins in the East Sengkang Basin are identified. Furthermore, the HGTA can also reveal lithological contacts very well. Tilt angle of the gradient amplitude (TAHG) technique provides an excellent description of the lineaments of both shallow and deeper buried geological structures. The TAHG approach and Euler deconvolution may define indications of depression zones and 24 new potential fault segments within the depression zones. A number of earthquakes that have happened near the fault segments support this fault assumption. The basement model derived from gravity data has extremely similar patterns and depth trends to that derived from seismic data.

Keywords: Structural configuration, Sengkang Basin, edge detection, Euler deconvolution, GGMPlus

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