Application of 3D Euler Deconvolution and 2D inverse modelling to basin depth estimation, the case of the Keta basin, Ghana

Abstract

3D Located Euler Deconvolution and 2D Inverse Modelling have been applied to aero-magnetic and gravity data, respectively, to estimate depth to the basement across the Keta-basin, Southeastern Ghana, West Africa. The Euler deconvolution estimated relative depths, illustrated by depth solutions across the entire basin while the inverse modelling estimated the absolute depth at various positions in the basin. To improve and provide more accurate depth solutions, we applied the Located 3D Euler Deconvolution Method instead of the Standard Euler Deconvolution. The Located Euler depth estimate were obtained by calculating an analytic signal grid, finding peaks in the grid, then using the peak locations for located 3D Euler deconvolution. This method produced far lesser solutions than the Standard 3D Euler deconvolution. To estimate absolute depths across the basin, 2D inverse models were created along with five profiles constructed across strike on the gravity bouguer anomaly map. An Iterative Least Squares Inversion Method which is a non-linear inversion technique was applied to automatically calculate the model parameter (depths) in each step of the iteration process. The inversion procedure can easily be integrated with geologically realistic models. Comparatively, both methods produced similar depth estimates. The study showed higher depths to the south and east of the study area (>2 km) as the shallower depth occurs to the north (<2 km). The relative thickness of sedimentary succession was inferred from the depth distribution patterns as observed from Euler depth solutions. The highest depth estimated was 3.57 km which occur further south of the basin. ARTICLE HISTORY

Parâmetros de regularização de operadores diferenciais no processamento de dados aeromagnéticos

“…O índice estrutural pode ser inferido de diversas maneiras: correlação entre a anomalia magnética e as estimativas do nível de base (Barbosa et al, 1999(Barbosa et al, , 2000Melo et al, 2013); cálculo dos menores desvios padrão para inferências do nível de base (Melo & Barbosa, 2017; combinação do método de Euler com as propriedades do sinal analítico (Salem & Ravat, 2003;Keating & Pilkington, 2004); ou através da similaridade para transformações diferenciais (Stavrev, 1997;Gerovska & Araúzo-Bravo, 2003;Stavrev et al, 2009). O índice estrutural para mapas contendo lineamentos magnéticos (por exemplo, zona de falhas) é geralmente assumido igual a 1 (Souza et al, 2015;Nuamah Daniel & Tandoh Kingsley, 2020).…”