Internal Compartmentalization of the Magadi Basin, Southern Kenya Rift: Insights from Aeromagnetic and Gravity Studies

Abstract

The southern Kenya Rift is characterized by complex faulting and internal compartmentalization. The aim of the research is to utilize aeromagnetic and gravity data to analyze compartmentalization, sediment thickness, and structural characterization. Using tilt derivatives, regional-residual separation, and Euler solutions allow for separating important structures, and lineaments. Euler solutions determine the depths and positions of causative sources. Unconstrained 3D susceptibility model reflects the compartments and surrounding geological formations. Compartmentalized structures are observed across three grabens, each with unique geological features and fault orientations. The first western graben displays tilted fault blocks and z-shaped depocenters, suggesting a strike-slip strain regime. Significant shifts in rifting style have influenced fault activity and strain concentration mechanisms. The Aswa-Nandi-Loita transfer zone greatly influences compartmentalization, fault structures, and sedimentary deposition. Analysis of sediment thickness reveals deeper signatures in the first graben that domiciles Musenke [2700m], Pakase [2600m], and Olkiramatian [1700m], depocenters. These variations are attributed to boundary fault constraints and volcanic manifestations influencing sedimentation patterns. The second graben exhibits thinner sedimentary compartments encompassing Magadi, Kordija, and Mile Forty-six. Structural characterization reveals rotated fault blocks dominating the first graben, axial zones characterized by E-W and NE-SW linear orthogonal structures in the second graben, and flexural regimes in the third graben.