## 7 Conclusions  
The granitoids of the Jabal Al Bayda area can be classified in terms of petrographic observations and geochemical data into monzogranite and alkali granite. The geochemical characteristics of the monzogranite, including high Ba-Sr signatures, high-K calc-alkaline to shoshonitic composition, and metaluminous to mildly peraluminous nature, suggest its formation in a subduction-related setting. The Jabal Al Bayda alkali granites exhibit different geochemical characteristics compared to the monzogranite. They have lower contents of Ba and Sr and a higher content of Rb. These features, along with their A-type characteristics, suggest a post-orogenic magmatic origin. The composition of the Jabal Al Bayda granitoids, including both the monzogranite and alkali A-type granites, are similar to many other granites found in the ANS. These Neoproterozoic granites are supposed to have formed by the partial melting of a heterogeneous metasedimentary source, consisting of variable proportions of metapelites and metagraywakes, with little contribution of metatonalitic source.  
It is concluded that the studied Jabal Al Bayda plutons were emplaced in a single orogenic cycle that encompasses the Pan-African orogen. This implies that the emplacement of the plutons occurred during the late stages of island-arc accretion and extended into the post-orogenic period. The transition from island-arc accretion to post-orogenic events, followed by orogen relaxation and the shift to anorogenic tectonic processes, suggests a complex and dynamic geological history. The development of the Najd fault system likely played a significant role in influencing these tectonic changes and the subsequent emplacement of the Jabal Al Bayda plutons.  
In connection with the regional geology and the magmatic evolutionary history, we assume that the Jabal Al Bayda monzogranite was formed by the partial melting of metagraywakes and tonalites in a subduction-related environment. The time of formation of these granites is attributed to late-orogenic magmatism (620-600 Ma). On the other hand, the low Ba-Sr and high Rb signatures of the Jabal Al Bayda A2-type alkali granite were generated by the partial melting of a metapelic source in a post-collisional setting. The timing of the formation of these granites is attributed to the late-orogenic magmatism (608-556 Ma), which marks the beginning of extension during the fourth stage of ANS evolution (\(\sim\)600-530 Ma).  
Figure 10: Simplified model for the tectonomagmatic evolution of the juvenile crust in the Jabal Al Bayda area, western Arabian Shield of Saudi Arabia. (**A**) Sketch diagram illustrating mode of formation of the subduction-related monzogranites in the study area. (**B**) Simplified profile along Midyan terrain in the NW to Hijaz-Jeddah terrains in the SW, illustrating mode of formation of the post-collisional alkali granites in the study area. TBUS means Thurwah-Bir Umq Suture. The crust and mantle thickness are not to scale.  
**Author Contributions:** Methodology, H.H.A. and Y.H.D.; Formal analysis, H.H.A. and Y.H.D.; Investigation, H.H.A. and Y.H.D.; Resources, H.H.A.; Data curation, Y.H.D.; Writing--original draft, H.H.A.; Writing--review & editing, H.H.A. and Y.H.D.; Visualization, H.H.A. and Y.H.D.; Supervision, Y.H.D.; Project administration, H.H.A.; Funding acquisition, H.H.A. All authors have read and agreed to the published version of the manuscript.  
This research work was funded by Institutional Fund Projects under grant no. (IFPIP-1443-145-1443).  
Not applicable.  
**Data Availability Statement:** The data presented in this study is contained within the article.  
The authors gratefully acknowledge technical and financial support from the Ministry of Education and King Abdulaziz University, Jeddah, Saudi Arabia. We would like to express our gratitude to the reviewers for their valuable comments and suggestions, which have greatly contributed to improving the quality of this manuscript.  
The authors declare no conflict of interest.