## 4 Results  
### Fine-Grained Turbidite Deposits  
The core of the shale is light gray to grayish black (Figure 3a). Low-amplitude, long-wavelength climbing ripples are common. Under the microscope, the shale exhibits normal grading with nine typical subdivisions (T0-T8) as described by [PERSON] and [PERSON] (1980) [23]. **Basal lenticular laminae (T0)**: The subdivision represents the lowermost part of a graded laminated unit, with a total thickness of 2.8-3.5 cm. It is primarily composed of silt laminae intercalated with small amounts of lenticular mud laminae. Within a single bed, the grain size gradually decreases from coarse silt to fine silt and even clay upwards (Figure 4a). The base is sharp and irregular, showing evidence of scouring, load casts, and mud injection structures. Internally, the subdivision contains abundant bioclasts along with a few escape structures. Upward, the sedimentary structures evolve from cross lamination (2 cm thick), to small-scale cross lamination (1.5 cm), to planar lamination (0.5 cm), and finally to fading ripples. The upper surface of the subdivision is either sharp or gradational, with a wavy or current-lineated appearance. **Convolute laminae (T1)**: The subdivision is 0.9-1.9 cm thick, with a wavy, sharp contact with the underlying T0 (Figure 4b) and a gradational contact with the overlying T2. It is composed of silt laminae with abundant bioclasts and traces of mud laminae. Internally, convolute laminae are intercalated with chaotic dark strips. Compared to the T0 subdivision, this unit contains finer silt and higher clay mineral content. **Wavy-lenticular laminae (T2)**: The subdivision is 1.1-3.4 cm thick, with gradational contacts with both the underlying T1 and the overlying T3 (Figure 4b). It is primarily composed of silt laminae intercalated with thin mud laminae occurring in small troughs [24]. Upward, the silt content decreases, and the grain size becomes finer, forming a normal grading. Low-amplitude, long-wavelength climbing ripples are commonly observed, appearing discontinuous and lenticular in shape (Figure 4b). Figure 3: Core photos showing different types of sedimentary characteristics of the Wufeng Formation in the southern Sichuan Basin. (**a**) Fine-grained turbidite deposits, well Y101H3-8, 3791.2 m; (**b**) Hemipelagic deposits, well Y101H3-8, 3695.4 m; (**c**) Shallow shoal deposits, well Y101H3-8, 3689.7 m.  
**Thin regular laminae (T3)**: The subdivision T3 is 0.5-1.0 cm thick, with gradational contact with both the underlying T2 and overlying T4. It consists of alternating graded silt laminae and mud laminae, with thicker and coarser silt laminae at the base and thicker mud laminae with fine silt laminae near the top. The bed surfaces are wavy, continuous, and sharp (Figure 4c). Small scouring structures are often observed at the base of the silt-clay graded beds, along with small wavy laminations and foresets. **Indistinct laminae (T4)**: The subdivision is commonly 1.2 cm thick and has gradational contacts with both the underlying T3 and overlying T5 (Figure 4d). It is mainly composed of mud laminae, with minor striped or lenticular silt laminae that are generally poorly continuous. This subdivision is characterized by graded planar lamination with  
Figure 4: Large slab photos showing characteristics of the Stow sequence of the fine-grained turbidite deposits. (**a**) Y101H3-8, 3791.2 m; (**b**) Y101H3-8, 3792.3 m; (**c**) Y101H3-8, 3790.4 m; (**d**) DA2, 3598.4 m; (**e**) DA2, 3597.6 m; (**f**) Y101H3-8, 3798.5 m.  
unclear interfaces and slight variations of grain size, color, and mineral composition within a laminase. **Wispy silt laminae (T5)**: The subdivision is commonly 0.5-1.7 cm thick (typically 1.2 cm) and has gradational contacts with both the underlying subdivision T4 and overlying subdivision T6 (Figure 4d,e). It is mainly composed of mud laminae with a small amount of silt laminae in wispy or chaotic forms.