Shallow Crustal Velocity Structure of the Wuyi Metallogenic Belt, Cathaysia Block, From First‐Arrival Tomography: Implications for Late Mesozoic Mineralization

The eastern Cathaysia Block in South China experienced intense tectono‐magmatic activity during the Late Mesozoic, resulting in abundant metallic mineral resources. However, the high‐resolution velocity structure of the shallow upper crust remains poorly resolved, despite its critical role in orebody occurrence and fluid migration. Based on a 300‐km‐long seismic line spanning the Wuyi metallogenic belt in the Cathaysia Block, we used first‐arrival traveltime tomography to obtain a high‐resolution velocity structure for the uppermost ∼1–2 km. The results reveal pronounced lateral heterogeneity in the shallow velocity structure across the study area. When integrated with geological data, the velocity boundaries delineate mapped faults and lithologic contacts and also reveal possible concealed structures. Different metallogenic districts exhibit distinct velocity structures. The epithermal uranium ore district is characterized by a lateral transition from a high‐velocity basement to a low‐velocity basin, whereas the skarn iron district features a vertical configuration of shallow low‐velocity anomalies overlying deeper high‐velocity anomalies. Fault‐related structures played different roles, promoting basin subsidence and preservation of uranium mineralization in Ruijin and providing accommodation for intrusions and pathways for ore‐forming fluids in Longyan. Combined with previous regional studies, these shallow structural variations are interpreted within a broader tectono‐magmatic framework involving lithospheric extension and Paleo‐Pacific rollback.