## 7 Conclusions  
1. LA-ICP-MS zircon U-Pb dating of the volcanic rocks in the Fuyun-Qinghe area revealed that the basalt from the Qiaoxiahala mining area formed at 401.7 \(\pm\) 4.7 Ma, while the andesites from Kurt town yielded ages of 405.1 \(\pm\) 5.6 Ma and 404.8 \(\pm\) 6.7 Ma. The volcanic breccia from Kurt town was dated to 382.9 \(\pm\) 3.4 Ma. These results indicate that the rocks were formed during the Early-Middle Devonian.  
2. The Early-Middle Devonian volcanic rocks in the Fuyun-Qinghe area have both alkaline and subalkaline series rocks in the TAS diagram, with rock assemblages including hawaiite, mugearite, potassic brachy basalt, basaltic andesite, andesite, bemmoreite, etc., which contained special magmatic arc rock assemblages such as adakite, sub-boninite, NEAB, picrite, HMA, and MA. They were enriched in LILEs and depleted in HFSEs, exhibiting similar geochemical characteristics to the magmatic arc rocks formed by the Taitao Ridge subduction in Chile.  
3. The basaltic rocks (including NEAB), sub-boninite, and HMA originated from the partial melting of garnet-spinel mantle peridotite metasomatized by subducted fluids (melts), with some rocks likely incorporating asthenospheric materials. In contrast, the MA and adakite were likely produced by the partial melting of the young and hot subducting oceanic crust (slab) and subsequent interaction with the mantle wedge peridotite.  
4. The rock assemblages and petrogeochemical characteristics of Fuyun-Qinghe samples closely resemble those of the Taitao Ridge and Taitao Peninsula magmatic arc by the Taitao Ridge subduction during the Neogene-Quaternary period at the Chile Triple Junction. Based on these similarities, we propose that the Fuyun-Qinghe area was likely situated in a magmatic arc setting formed by the PAO ridge subduction during the Early-Middle Devonian.  
The following supporting information can be downloaded at [[https://www.mdpi.com/article/10.3390/app15073736/s1](https://www.mdpi.com/article/10.3390/app15073736/s1)]([https://www.mdpi.com/article/10.3390/app15073736/s1](https://www.mdpi.com/article/10.3390/app15073736/s1)). Table S1: LA-ICP-MS zircon U-Pb dating data for the volcanic rocks in the Fuyun-Qinghe area; Table S2: Major (\(\%\)) element data for the volcanic rocks in the Fuyun-Qinghe area; Table S3: Trace (ppm) element data for the volcanic rocks in the Fuyun-Qinghe area; Table S4: Lu-Hf isotopic data for the volcanic rocks in the Fuyun-Qinghe area.  
Conceptualization, J.L. and C.L.; writing, J.L.; review and editing, C.L. and Q.L.; supervision, Z.L. and Y.L.; investigation, J.L., C.Z., X.G., X.Y. and M.W. All authors have read and agreed to the published version of the manuscript.  
This study was supported by the China Geological Survey Project (DD20221645, DD20190370, 1212011121075) and the National Natural Science Foundation of China (Grants No. 92162213 and 40802020).  
Not applicable.  
Data availability Statement: Data are contained within the article and Supplementary Materials.  
We extend our gratitude to [PERSON] from AGRS and [PERSON] from the Geological Survey Institute of Xinjiang Uygur Autonomous Region, China, for their support in field work and sample collection, and gratefully acknowledge the Inner Mongolia Geological Survey Institute for complimentary providing zircon geochronological analyses and testing services. Special appreciation is extended to [PERSON] and [PERSON] from the institute for their professional support throughout the analytical work, including sample testing procedures, data interpretation, and technical consultation. We also appreciate the insightful comments provided by the reviewers.  
Author [PERSON] was employed by the company China National Nuclear Corporation. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.