| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 4701509 | Earth Science Frontiers | 2009 | 6 Pages |
The Quaternary Sebei formation is a type of lacustrine deposit developed in the center of depressed lake basin with low-dipping dome-shaped inherited geomorphological environment in Tainan area, Qaidam Basin. The sedimentary strata are composed of weakly consolidated silty to fine-grained sandstone and mudstone. In this article, data obtained from the special coring analysis under sealing high-pressure nitrogen method were used to study the lithofacies. It is proved that seven types of lithofacies and five types of facies association could be classified in the Quaternary Sebei Formation in the Tainan Area. Accordingly, three types of microfacies (sometimes called energy units) could be acquired, including sandbars, beach sands, and mud flats. These three types of microfacies are orderly distributed. The sandbars are concentrated on the higher portion of the dome and close to the low water level of the lake. The beach sands are concentrated on the flanks of the dome and below the low water level of the lake. The sandbars are always intercalated with the beach sands. The mud flats are concentrated in the synclinal part and could extend to the entire area when the level of the lake water moved relatively upwards. The physical property of the sandbars is better than that of the beach sands, and the homogeneity of the sandbars are better than that of the beach sands. The mud flat acts not only as the source of the biogenic gas but also as the infiltrating barrier of the natural gas.
