Summary
The Yanan Formation, alternatively spelled the Yan'an Formation (Chinese: 延安组), is a geological formation in China, it is also alternatively considered a group. The age of the formation is uncertain, with estimates ranging from Toarcian to Bajocian. It is divided up into 5 members, with the designation of Y1 through Y5. Y2, Y3 and Y4 are predominantly dark shales, while Y1 and Y5 are composed of sandstones, coal beds[1] and interbedded mudstones. The depositional environment at the time was when the Ordos Basin formed a large inland lake, surrounded by floodplains. The dark shales have been explored for the potential of producing shale gas.[2] The coal has also been explored for the production of coalbed methane.[3] The formation is also notable for its fossil content, with dinosaur footprints having been found in the formation.[4] The dinosaur Lingwulong was formerly thought to have been found in this formation,[5] but the strata was later attributed to the overlying Zhiluo Formation.[6]
| Yanan Formation | |
|---|---|
| Stratigraphic range: | |
| Type | Geological formation |
| Sub-units | Y1, Y2, Y3, Y4, Y5 |
| Underlies | Zhiluo Formation |
| Overlies | Fuxian Formation |
| Thickness | up to 220 metres (720 ft) |
| Lithology | |
| Primary | Sandstone, siltstone, mudstone, shale |
| Other | Coal |
| Location | |
| Coordinates | 38°06′N 106°42′E / 38.1°N 106.7°E |
| Approximate paleocoordinates | 42°06′N 111°42′E / 42.1°N 111.7°E |
| Region | Ningxia, Shaanxi, Inner Mongolia |
| Country |  China |
| Extent | Ordos Basin |
| Type section | |
| Named for | Yan'an |
  Yanan Formation (China)  Yanan Formation (Ningxia) | |
References edit
- ^ Ao, Weihua; Huang, Wenhui; Weng, Chengmin; Xiao, Xiuling; Liu, Dameng; Tang, Xiuyi; Chen, Ping; Zhao, Zhigen; Wan, Huan (January 2012). "Coal petrology and genesis of Jurassic coal in the Ordos Basin, China". Geoscience Frontiers. 3 (1): 85–95. Bibcode:2012GeoFr...3...85A. doi:10.1016/j.gsf.2011.09.004. ISSN 1674-9871.
- ^ Wang, Dong-dong; Shao, Long-yi; LI, Zhi-xue; LI, Ming-pei; Lv, Dawei; Liu, Haiyan (September 2016). "Hydrocarbon generation characteristics, reserving performance and preservation conditions of continental coal measure shale gas: A case study of Mid-Jurassic shale gas in the Yan'an Formation, Ordos Basin". Journal of Petroleum Science and Engineering. 145: 609–628. Bibcode:2016JPSE..145..609W. doi:10.1016/j.petrol.2016.06.031. ISSN 0920-4105.
- ^ Xu, H.; Tang, D.Z.; Liu, D.M.; Tang, S.H.; Yang, F.; Chen, X.Z.; He, W.; Deng, C.M. (June 2012). "Study on coalbed methane accumulation characteristics and favorable areas in the Binchang area, southwestern Ordos Basin, China". International Journal of Coal Geology. 95: 1–11. Bibcode:2012IJCG...95....1X. doi:10.1016/j.coal.2012.02.001. ISSN 0166-5162.
- ^ Xing, Lida; Lockley, Martin G.; Tang, Yonggang; Klein, Hendrik; Zhang, Jianping; Persons, W. Scott; Dai, Hui; Ye, Yong (2015-01-02). "Theropod and Ornithischian Footprints from the Middle Jurassic Yanan Formation of Zizhou County, Shaanxi, China". Ichnos. 22 (1): 1–11. doi:10.1080/10420940.2014.985670. ISSN 1042-0940. S2CID 129509962.
- ^ Xu, Xing; Upchurch, Paul; Mannion, Philip D.; Barrett, Paul M.; Regalado-Fernandez, Omar R.; Mo, Jinyou; Ma, Jinfu; Liu, Hongan (2018-07-24). "A new Middle Jurassic diplodocoid suggests an earlier dispersal and diversification of sauropod dinosaurs". Nature Communications. 9 (1): 2700. Bibcode:2018NatCo...9.2700X. doi:10.1038/s41467-018-05128-1. ISSN 2041-1723. PMC 6057878. PMID 30042444.
- ^ Dai, Hui; Tan, Chao; Xiong, Can; Ma, Qingyu; Li, Ning; Yu, Haidong; Wei, Zhaoying; Wang, Ping; Yi, Jian; Wei, Guangbiao; You, Hailu; Ren, Xinxin (2022). "New macronarian from the Middle Jurassic of Chongqing, China: phylogenetic and biogeographic implications for neosauropod dinosaur evolution". Royal Society Open Science. 9 (11): 220794. Bibcode:2022RSOS....920794D. doi:10.1098/rsos.220794. PMC 9627447. PMID 36340515.