## 3 Results
### Genetic Analysis of Sandbodies
#### 3.3.3. Tectonic Activity  
Tectonic activity fundamentally controls sedimentary system evolution and sandbody distribution in the HHK Depression [46; 47]. The Paleogene structural framework features a \"steep northern margin, gentle southern slope, western deep depression, eastern shallow \begin{table}
\begin{tabular}{c c c c c c c c c} \hline
**Formation** & **Well** & **Fe/Mn** & **H (s)** & **Paleob bathymetry (m)** & **Formation** & **Well** & **Fe/Mn** & **H (s)** & **Paleob bathymetry (m)** \\ \hline \(E_{\text{3}}\)\(s_{1}\) & B7-2c & 96.9 & 1.127 & 17 & \(E_{\text{3}}\)\(d_{2}\) & C4-9-d2 & 93.69 & 1.386 & 27.7 \\ \(E_{\text{3}}\)\(s_{1}\) & B6-2 bD & 96.75 & 1.121 & 17.5 & \(E_{\text{3}}\)\(d_{2}\) & B3-3a & 91.92 & 1.64 & 33.6 \\ \(E_{\text{3}}\)\(s_{2}\) & C4-9d & 94.47 & 1.37 & 25.1 & \(E_{\text{3}}\)\(d_{2}\) & C4-9d & 92.37 & 1.61 & 32.1 \\ \(E_{\text{3}}\)\(s_{1}\) & C4-9e-a & 95.97 & 1.22 & 20.1 & \(E_{\text{3}}\)\(d_{2}\) & C4-9e-a & 91.02 & 1.73 & 36.6 \\ \(E_{\text{3}}\)\(s_{2}\) & C4-9e & 99.93 & 0.56 & 6.9 & \(E_{\text{3}}\)\(d_{2}\) & B6-5a & 92.01 & 1.63 & 33.3 \\ \(E_{\text{3}}\)\(s_{2}\) & B7-2c & 96.78 & 1.09 & 17.4 & \(E_{\text{3}}\)\(d_{2}\) & C4-9d & 93.50 & 1.46 & 28.33 \\ \(E_{\text{3}}\)\(s_{2}\) & C4-9e-a & 97.92 & 0.96 & 13.6 & \(E_{\text{3}}\)\(d_{2}\) & C4-9e & 93.59 & 1.38 & 26.7 \\ \hline \end{tabular}
\end{table} 
Table 4: Characteristics of paleobathymetry in the HHK Depression during the Paleogene. Figure 8: Paleowater depth and paleogeography of the HHK Depression during the Paleogene. (**a**) Paleobathymetry characteristics of the Shajie Formation; (**b**) paleobathymetry characteristics of the \(\text{E}_{\text{3}}\)\(d_{2}\)\({}^{\text{L}}\) submember; (**c**) Paleomorphological recovery map of the \(\text{E}_{\text{3}}\)\(d_{2}\)\({}^{\text{L}}\) submember; (**d**) contour map of stratigraphic thickness of the \(\text{E}_{\text{3}}\)\(d_{2}\)\({}^{\text{L}}\) submember. platform, with central uplift\" configuration (Figure 1). The western segment of the intra-basin Tan-Lu strike-slip fault generated NNE-trending master faults and EW-oriented branching faults, sub-dividing the depression into the following: northern steep slope (eastern/western segments); southern slope (eastern/western segments); central strike-slip zone; central uplift zone; northwestern sub-depression; southwestern sub-depression; and eastern depression (Figure 1c). Seismic stratigraphic interpretation reveals Nitric master faults forming synthetic/antithetic \"Y\"-shaped, graben-horst, and step-like fault assemblages (Figure 2). Right lateral strike-slip motion produced en echelon arranged linear master faults along the central structural belt, with EW-trending subsidiary faults emanating from the central uplift (Figure 8c). Kinematic analysis [39] demonstrates that E-W normal faults and NNE strike-slip faults jointly govern beach-bar sandbody distribution. During the Dongying Formation deposition (rift-depression transition phase), fault reactivation intensified tectonic activity. Paleogeographic reconstructions and seismic profiles (T\({}_{3}\) to T\({}_{3}\)U) delineate secondary structural units (Figure 8c), dominated by the following two fault sets: NNE-trending throughgoing faults controlling deep architecture and strike orientation, and E-W faults modulating local relief. The NE-SW-trending basin exhibits a \"southern high-northern low, central uplift-peripheral sag\" geometry [48]. Tectonism drove paleotopographic development, directly influencing sandbody distribution. From E\({}_{3}\)d\({}_{3}\) to E\({}_{3}\)d\({}_{2}\)\({}^{1}\), the central strike-slip and uplift zones experienced sustained uplift, creating trough-margin highs. The central strike-slip zone formed an underwater structural high, while the central uplift zone partitioned northern/southern provenance areas. During E\({}_{3}\)d\({}_{2}\)\({}^{1}\) deposition, the paleotopographic relief (time-domain) ranged around 100-500 ms TWT.