Yanan Formation

Yanan Formation
Stratigraphic range: Toarcian–Bajocian
TypeGeological formation
Sub-unitsY1, Y2, Y3, Y4, Y5
UnderliesZhiluo Formation
OverliesFuxian Formation
Thicknessup to 220 metres (720 ft)
Lithology
PrimarySandstone, siltstone, mudstone, shale
OtherCoal
Location
Coordinates38°06′N 106°42′E / 38.1°N 106.7°E / 38.1; 106.7
Approximate paleocoordinates42°06′N 111°42′E / 42.1°N 111.7°E / 42.1; 111.7
RegionNingxia, Shaanxi, Inner Mongolia
CountryChina
ExtentOrdos Basin
Type section
Named forYan'an
Yanan Formation is located in China
Yanan Formation
Yanan Formation (China)
Yanan Formation is located in Ningxia
Yanan Formation
Yanan Formation (Ningxia)

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 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. The coal has also been explored for the production of coalbed methane. The formation is also notable for its fossil content, with dinosaur footprints having been found in the formation. The dinosaur Lingwulong was formerly thought to have been found in this formation, but the strata was later attributed to the overlying Zhiluo Formation.

Fossil content

Color key
Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon

Notes
Uncertain or tentative taxa are in small text
crossed out taxa are discredited.

Dinosaurs

Sauropods

Sauropods of the Yanan Formation
Genus Species Location Stratigraphic position Material Notes Images
Lingwulong L. shenqi A diplodocoid sauropod. The attribution to the Yanan Formation was later found to be erroneous, and the species actually comes from the overlying Zhiluo Formation.

Insects

Insects of the Yanan Formation
Genus Species Location Stratigraphic position Material Notes Images
Junfengi J. yulinensis A campterophlebiid damsel-dragonfly
Kisa K. fasciata An archijassid hemipteran
Orthophlebia O. lini An orthophlebiid mecopteran
Parasinitsia P. qingyunensis A campterophlebiid damsel-dragonfly
Pseudoundacypha P. yananensis A thrips
Qibinius Q. maculatus A froghopper
Samaroblatta S. frondoidis A caloblattinid
Sinagonophlebia S. yananensis A paragonophlebiid damsel-dragonfly
Sinolocustopsis S. brevis A locustopsid orthopteran
S. elongatus A locustopsid orthopteran
Sinopsocus S. yananensis A protopsyllidiid hemipteran
Subaphidulum S. sinica A protopsyllidiid hemipteran
Yananphasma Y. chresmodoides A susumaniid phasmatodean
Yananphilius Y. peizhuangensis A sepulcid hymenopteran
Yananthemis Y. zaoyuanensis A selenothemistid damsel-dragonfly

Plants

Plants of the Yanan Formation
Genus Species Location Stratigraphic position Material Notes Images
Selaginellites S. huatingensis A spikemoss

References

  1. ↑ 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.
  2. ↑ 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.
  3. ↑ 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.
  4. ↑ 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. Bibcode:2015Ichno..22....1X. doi:10.1080/10420940.2014.985670. ISSN 1042-0940. S2CID 129509962.
  5. ↑ 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.
  6. 1 2 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. However, valid Middle Jurassic neosauropods are rarely reported before the discovery of dicraeosaurid Lingwulong from middle/late Middle Jurassic (late Bathonian–early Callovian) (The horizon was revised from Yan'an Formation (Aalenian–Bajocian) to Zhiluo Formation (Bathonian–early Oxfordian)
  7. ↑ Xing Xu; Paul Upchurch; Philip D. Mannion; Paul M. Barrett; Omar R. Regalado-Fernandez; Jinyou Mo; Jinfu Ma; Hongan Liu (2018). "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. PMC 6057878. PMID 30042444.
  8. ↑ Zheng, D.; Dong, C.; Wang, H.; Ye, Y.; Wang, B.; Chang, S.-C.; Zhang, H. (2017). "The first damsel-dragonfly (Odonata: Isophlebioidea: Campterophlebiidae) from the Middle Jurassic of Shaanxi Province, northwestern China". Alcheringa: An Australasian Journal of Palaeontology. 41 (4): 509–513. doi:10.1080/03115518.2017.1318170. S2CID 133806124.
  9. ↑ Fu, Y.; Xu, M.; Gao, J.; Huang, D. (2023). "The Archijassidae from the Jurassic of China (Hemiptera, Cicadomorpha, Membracoidea) and its palaeoecological significance". Historical Biology: An International Journal of Paleobiology. 36 (10): 2233–2238. doi:10.1080/08912963.2023.2250109. S2CID 261636256.
  10. ↑ Lian, X.-N.; Cai, C.-Y.; Feng, Z.; Huang, D.-Y. (2024). "New orthophlebiid mecopteran from the Middle Jurassic Yan'an Formation, China". Journal of Insect Biodiversity. 60 (1): 47–54. doi:10.12976/jib/2024.60.1.8.
  11. ↑ Tian, F.; Zheng, D.; Nel, A.; Ye, Y.; Mei, T.; Zhang, H. (2023). "A new campterophlebiid damsel-dragonfly (Odonata: Isophlebioidea) from the Middle Jurassic Yanan Formation of Yulin City, Shaanxi Province, NW China". Comptes Rendus Palevol. 22 (23): 491–496. doi:10.5852/cr-palevol2023v22a23. S2CID 259852598.
  12. ↑ Huang, D.Y. (2023). "Discovery of Thripida from the Middle Jurassic Yan'an Formation". Zootaxa. 5396 (1): 22–25. doi:10.11646/zootaxa.5396.1.6. PMID 38220986. S2CID 266659877.
  13. ↑ Fu, Y.; Huang, D. (2020). "A new fossil cercopoid from the middle Jurassic Ordos and Jiyuan basins, northern China (Hemiptera, Cicadomorpha)". Historical Biology: An International Journal of Paleobiology. 33 (10): 2025–2030. doi:10.1080/08912963.2020.1765167. S2CID 219747247.
  14. ↑ Liang, Junhui; Shih, Chungkun; Ren, Dong (2019), "Blattaria – Cockroaches", in Ren, Dong; Shih, Chung Kun; Gao, Taiping; Yao, Yunzhi; Wang, Yongjie (eds.), Rhythms of Insect Evolution: Evidence from the Jurassic and Cretaceous in Northern China, pp. 91–112, doi:10.1002/9781119427957.ch7, ISBN 978-1-119-42795-7
  15. 1 2 Nel, A.; Xu, M.; Wang, Y.; Song, X.; Gao, J.; Ji, G.; Huang, D. (2024). "New Chinese Jurassic damsel-dragonflies of the families Paragonophlebiidae, Selenothemistidae and Isophlebiidae (Odonata, Epiproctophora) from the Jurassic Ordos Basin of NW China". Geobios. 87: 37–44. doi:10.1016/j.geobios.2024.08.014.
  16. ↑ Nel, A.; Huang, D.-Y. (2024). "New locustopsid fossils from the Middle Jurassic Yan'an Formation (Orthoptera: Caelifera)". Journal of Insect Biodiversity. 60 (1): 16–23.
  17. 1 2 Xu, M.-M.; Hakim, M.; Huang, D.-Y. (2023). "New Jurassic protopsyllidiids from the Yan'an Formation, North China (Insecta: Hemiptera)". Palaeoentomology. 6 (5): 542–548. doi:10.11646/palaeoentomology.6.5.13. S2CID 264597972.
  18. ↑ Guo, Q.-M.; Xu, C.-P.; Nel, A.; Peng, A.-C.; Wen, Z.-G.; Li, T.; Fang, R.; Zheng, D.-R. (2025). "A new genus and species of Susumaniidae (Insecta: Phasmatodea) from the Middle Jurassic of Shaanxi Province, Northwest China". Palaeoworld. 34 (5) 200942. doi:10.1016/j.palwor.2025.200942.
  19. ↑ Jouault, C. (2024). "A new parapamphiliin wasp (Hymenoptera: Sepulcidae) from the Middle Jurassic Yan'an Formation, China". Journal of Insect Biodiversity. 60 (1): 83–88. doi:10.12976/jib/2024.60.1.12.
  20. ↑ Song, Z.-H.; Wang, Z.-E.; Wang, H.; Li, X.; Wu, J.-Y.; Ding, S.-T. (2026). "First macrofossil record of Selaginellites from the Jurassic of northwestern China". Review of Palaeobotany and Palynology. 348 105534. Bibcode:2026RPaPa.34805534S. doi:10.1016/j.revpalbo.2026.105534.