# Geometry and Kinematics of the Central Fault Zone, Fula Sag, Central Africa Shear Zone  
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1 Correspondence: [EMAIL_ADDRESS] (G.Z.); [EMAIL_ADDRESS] (G.W.)  
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Footnote 1: email: {yang202  
relay ramps develop during the growth process of faults. Therefore, studying the geometry and the segmental growth of the main faults on the CFZs in CASZ is helpful to predict the locations of lithologic reservoirs, providing a reference for later hydrocarbon exploration.  
Several studies have discussed the geological model of rift basins in the CASZ [17; 18; 19; 20]. The analysis demonstrates that basins in CASZ have roughly experienced three phases of rifting cycles since the Early Cretaceous due to the Atlantic opening, the rapid opening of the Indian Ocean, and the opening of the Red Sea rift. Some studies also address the geometry of the present-day CFZs in CASZ [21; 22; 23; 24; 25; 26], which provides limited information on the segmental growth process of the normal faults and is unable to restore the kinematics. For instance, some interpreted the CFZ in Fula sag, middle CASZ as the synthetic approaching or convergent approaching transfer zone [24; 25] according to [PERSON]'s classification of the transfer zones [27]. However, others argued that it exhibits characteristics of the convergent overlapping transfer zone [26].  
Various models of normal fault evolution have been proposed in the literature, involving a progression from underlapping to overlapping fault geometries over time [28; 29; 30; 31; 32; 33; 34; 35]. These models suggest that faults grow by lengthening their segments until they eventually overlap and become spatially closer, leading to fault linkage. The growth of fault segments involves different stages, including isolated growth, soft linkage (where fault surfaces are isolated but connected by ductile strain in the rock volume between them), and hard linkage (where fault surfaces are joined) [29; 36]. Characteristically, there is variability in throw-distance profiles for fault segments and linked faults as they interact and undergo linkage. Throw transfer through relay ramps results in steep throw gradients along fault segments at oversteps [28].  
Currently, there are two main methods for throw and segmentation growth recovery of faults that are able to restore the segmental growth process of main faults in the CFZs of CASZ: the vertical subtraction method [36; 37; 38] and the maximum throw subtraction method [39]. The vertical subtraction method, however, is applicable only to the \"throw accumulation--length fixed\" fault growth mode. For tectonic-genetic faults, the maximum throw during fault segment growth increases linearly with the extension length [40; 41; 42; 43], so the maximum throw subtraction method can truly reflect the evolutionary history of fault segment growth.  
This paper uses the 3-D throw mapping technique and the maximum throw subtraction method to present a detailed description and analysis of the CFZ on the Fula sag and middle CASZ. The aim is to demonstrate a comprehensive understanding of the geometrical and kinematic evolution of an extensional CFZ in the intracontinental passive rift basin based on well-documented growth strata that constrain detailed spatial and temporal fold-fault development.