# Geometry and Kinematics of the Central Fault Zone, Fula Sag, Central Africa Shear Zone
## 6 Growth Analysis of the Main Faults
The presented plots depict the growth process of Fault F3, demonstrating that the four individual fault segments comprising Fault F3 became active during the Darfur period. Subsequently, two of them entered the soft-linkage stage during the Amal period and they all further advanced to the hard-linkage stage during the third rifting, eventually coalescing to form a fully grown, large fault. Based on the typical profile data and the deposition time of each geological period from the previous research [23], we obtain the statistical map of the throw accumulation rate of the fault segments in each geological period, which allows us to quantify the activity intensity of these fault segments. Comparing longitudinally the throw accumulation rates for the same profile at different times (Figure 9), we find that the weakest fault activity occurs during the first rifting. Only fault F\({}_{2-2}\) (Profile j in Figure 9) was then active, and the throw accumulation rate is just 0.2 ms/Myr The fault activity grew stronger in the second rifting, and the activity of all the fault segments in the three main faults grew very intense, with the average throw accumulation rate reaching 4.2 ms/Myr. Of particular note is fault F\({}_{1-2}\) (Profile b in Figure 9) in the south of fault F\({}_{1}\), which reached a rate of 8.4 ms/Myr. The third rifting saw a rapid drop in fault activity, with the average throw accumulation rate going down to merely 1.9 ms/Myr. Even for fault F\({}_{2-2}\) (Profile j in Figure 9), its throw accumulation rate is only 0.8 ms/Myr during this period. In general, the activity intensity of fault segments is featured by \"extremely weak-strongest-weak\" in these three rifting cycles. Located in the south of the CFZ, the fault F\({}_{1-2}\) (Profile b in Figure 9) of fault F\({}_{1}\) was the most active during the second rifting, with its throw accumulation rate reaching 8.4 ms/Myr. The fault F\({}_{2-3}\) of fault F\({}_{3}\) (Profile k in Figure 9) was located in the north of the CFZ and emerged as the most active during the third rifting, with its throw accumulation rate reaching 5.7 ms/Myr. It can be seen that the extensional action within the CFZ was uneven on the plan, and rapid northward migration of the extensional center occurred from the second rifting to the third rifting. Figure 8: Relation between fault throw and extension distance of fault F\({}_{2}\). The provided diagrams illustrate the progressive growth of Fault F\({}_{2}\), showing that the three distinct fault segments forming Fault F\({}_{2}\) became active at different times, starting from the Bentiu period and continuing until the Amal period. Subsequently, two of these segments, F\({}_{2-1}\) and F\({}_{2-2}\), transitioned into the soft-linkage stage during the Amal period, and all segments further advanced to the hard-linkage stage during the third rifting, ultimately merging to form a fully developed, large fault. Thus, the main faults comprising the CFZ have been active mainly since the second rifting. The fault segments that make up the main faults of the CFZ were in the isolated growth stage during the second syn-rift, partially entered the soft-linkage stage during the post-rift of the second rifting, and went through the hard-linkage stage and then eventually formed full-grown faults from the third rifting until now (Figure 10). The above faults weakened abruptly in activity intensity during the transition period of these two rifting cycles. The extensional center in the study area underwent a rapid northward migration during the last two rifting cycles. Figure 10: Evolution of the main faults by segment linkage on the top Bentiu Fm. in the CFZ. (**a**) Isolated fault segments grow from their tips during the second syn-rift. (**b**) Overlap of fault segments leads to soft linkage and the development of relay ramp structures during the post-rift of the second rifting. (**c**) Continued fault growth eventually leads to breaching and concealing of the relay ramps as the fault segments become hard-linked in the third rifting.