Table 4. Corresponding Relationship among Sedimentary Facies, Dark Mudstone, and Organic Matter Abundance of the Pingdiquan Formation in the Dongdaohaizi Sag.
| sedimentary facies | sample number | the average thickness of brown mudstone (m) | the average thickness of dark mudstone (m) |  |
 |
average TOC (%) | average (S1 + S2)(mg/g) |
|---|---|---|---|---|---|---|---|
| Fan delta front | 32 | 30.3 | 70.6 | 32 | 52 | 0.754 | 0.993 |
| Prefan delta | 15 | 6.0 | 218.5 | 46 | 47 | 1.941 | 4.661 |
| Shore-shallow lake | 6 | 15.7 | 244.5 | 51 | 54 | 1.586 | 4.773 |
| Semideep lake | 19 | 24.6 | 575.8 | 69 | 72 | 2.768 | 4.872 |