## 2 Study Area and Data
### Mine Big Data
#### 2.2.1 UAS Imagery--Multispectral, LiDAR, Aeromagnetic
Finally, we conducted a UAV airborne magnetic anomaly survey in the mining area using the rubidium vapor magnetometer which is produced by QuSpin Inc. (Louisville, CO, USA). The magnetometer has a sampling range of 1000-100,000 nT and a maximum sampling rate of 400 Hz and records GPS data at a frequency of 20 Hz. During the flight, the magnetometer was securely mounted on the side of the UAV, with its axis parallel and perpendicular to the UAV's main axis, maintaining an altitude of 80 m AGL for airborne measurements. To eliminate the effects of diurnal variations during magnetic surveys, a magnetic base station was established at a location over 100 m away from the mining area to avoid the influence of external magnetic field changes on the recorded data. We calculated the total magnetic field Bt and used its variations to correct the UAV-borne total magnetic field data. Additionally, we computed the International Geomagnetic Reference Field (IGRF) for the area, which indicated a background field of approximately 53,973.053 nT, with a declination of about \(-7.698^{\circ}\) and an inclination of approximately 58.565\({}^{\circ}\). Using the Geosoft Oasis Montaj 8.4.1, we applied preprocessing operations to the UAV magnetic survey data, including diurnal variation correction, polarity reversal, and RTP filtering. The magnetic anomaly data after polarity reversal were then subjected to ordinary kriging interpolation, with results shown in Figure 5. Finally, the magnetic susceptibility parameter ranges for the main lithologies and strata in the Yanshan Iron Mine area were collected and tabulated, as shown in Table 2. \begin{table}
\begin{tabular}{c c c} \hline \multirow{2}{*}{**Strada/Lithology**} & \multicolumn{3}{c}{**Magnetic Susceptibility**} \\ \cline{2-3}  & **K (10\({}^{-64}\)IISI)** & **Jr (10\({}^{-3}\) A/m)** \\ \hline Quaternary & 0 & 0 \\ Changcheng Group & 0–300 & 0–200 \\ Migmatite & 0–500 & 0–200 \\ Biotite Granulite & 0–100 & 0–100 \\ Magnetite Quartzite & 30,000–150,000 & 5000–40,000 \\ \hline \end{tabular}
\end{table} 
Table 2: Range and average values of magnetic susceptibility for the main stratigraphy/lithology of the Yanshan iron ore deposit. Figure 4: UAV multispectral imagery: (**a**) image of April 2023; (**b**) image of September 2023; (**c**) image of May 2024. Based on the magnetic susceptibility range table for the main lithologies and strata in the Yanshan Iron Mine area, along with the polarity-reversed interpolated UAV magnetic imagery (as shown in Figure 5), it was observed that the magnetic susceptibility of the main ore (magnetic quartzite) ranges from 30,000 to 150,000 (10\({}^{-64}\)\(\pi\)SI), which is significantly higher than the magnetic susceptibility of the surrounding lithologies and strata. At the same time, the boundary between the ore body and the surrounding rocks is very distinct. Therefore, the magnetic characteristics can serve as an effective indicator to delineate the size and distribution contour of the Yanshan iron ore deposit. Different types of sensors can acquire multi-modal lightweight UAV remote sensing image data of the mining area, forming a multi-source aerial survey dataset of the open-pit mine to provide data for subsequent two-dimensional surface magnetite intelligent recognition and three-dimensional ore-forming prediction.