Amisan Formation
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Late Triassic geologic formation in South Korea
| Amisan Formation | |
|---|---|
| Stratigraphic range: Norian ~227–208.5 Ma | |
| Type | Geological formation |
| Unit of | Nampo Group |
| Underlies | Jogyeri Formation |
| Overlies | Hajo Formation |
| Thickness | 750–1,000 m (2,460–3,280 ft) |
| Lithology | |
| Primary | Shale, Sandstone, Siltstone and Coal |
| Location | |
| Region | South Chungcheong Province |
| Country | South Korea |
| Extent | Chungnam Basin |
| Type section | |
| Named for | Amisan, Boryeong |
 Map and diagram of Nampo Group | |
The Amisan Formation (Korean: 아미산층; Hanja: 峨嵋山層) is an Late Triassic geologic formation in Boryeong, South Korea. Fossil records from this formation include plants, insects, and fish remains.
The Amisan Formation in the Chungnam Basin overlies the Hajo Formation and underlies the Jogyeri Formation. It is subdivided into five zones based on its lithology, lower sandstone, lower shale, middle sandstone, middle shale, and upper sandstone zones. Depositional environments of the lower and middle shale zones of the Amisan Formation are thought to be lacustrine settings.
The depositional age of the Nampo Group including the Amisan Formation is debated,[1][2] but plant genera Lobatannularia from the Amisan Formation, and Sphenophyllum from the Baegunsa Formation, which overlies the Amisan Formation and the Jogyeri Formation suggests that the Upper Triassic spans to the Baegunsa Formation.[3] Also, conchostracan fossils and some insect fossils support the Triassic origin of the Amisan Formation.[4][5][6]
Fossil content
Most of the fossils from the Amisan Formation are from the lower shale zone and the middle shale zone.
Flora
| Flora of the Amisan Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Region | Member | Material | Notes | Image |
| Taeniopteris[7] |
|
|||||
Ferns
| Ferns of the Amisan Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Region | Member | Material | Notes | Image |
| Neocalamites | N. carrerei[8] | |||||
| Cladophlebis | C. nebbensis[9] | |||||
| Lobatannularia | L. sp.[7] | |||||
| Chiropteris | C. sp.[7] | |||||
| Equisetites[10] |
|
|||||
Bennettitales
| Bennettitales of the Amisan Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Region | Member | Material | Notes | Image |
| Anomozamites | A. baegunsaensis[11] | |||||
| Pterophyllum[11] |
|
|||||
| Weltrichia | W. sp.[12] | |||||
Gymnosperms
| Gymnosperms of the Amisan Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Region | Member | Material | Notes | Image |
| Podozamites | ||||||
| Anthrophyopsis | A. sp.[7] | |||||
| Drepanozamites | D. sp.[7] | |||||
| Baiera | B. cf. furcata[7][13] | |||||
| Cycadocarpidium | C. sp.[7] | |||||
| Ctenozamites | C. meogbangensis[11] | |||||
| Leptostrobus | L. myeongamensis[14] | |||||
Bivalves
| Bivalves of the Amisan Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Region | Member | Material | Notes | Image |
| Margaritifera | M. cf. isfarensis[15] | |||||
Conchostracans
| Conchostracans of the Amisan Formation[4] | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Region | Member | Material | Notes | Image |
| Euestheria |
|
|||||
| Cyclestherioides | C. rampoensis | |||||
| Sphaerestheria | S. koreanica | |||||
Insects
| Insects of the Amisan Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Region | Member | Material | Notes | Image |
| Turbidapsyche | T. dobrokhotovae | A mesopsychid scorpionfly; originally assigned to the genus Mesopsyche.[16][17][18] | ||||
| Siberioperlidae | Indeterminate | Stoneflies.[19] | ||||
| Platyperla | P. sp. | |||||
| Baleyopterygidae | Indeterminate | |||||
| Hallakkungis | H. amisanus | A palaeontinid.[20] |  | |||
| Tennentsia | T. koreana | A cicadomorph.[21] | ||||
| Sanmai | S?. zetavena | A tettigarctid.[22] | ||||
| Magnatitan | M. jongheoni | A titanopteran.[5] |  | |||
| Koreaphlebia | K. iussradiae | A triadophlebiomorph odonatopteran.[6] | ||||
| Koreatriassothemis | K. elongatus | A parazygopteran odonatopteran.[23] | ||||
| ?Isophlebioptera | Indeterminate | A possible Isophlebioptern nymph. Referred as 'Samarura-type' in paper.[23] | ||||
| Shurabia | S. taewani | A Geinitziid polyneopteran.[24] | ||||
Vertebrates
| Vertebrates of the Amisan Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Region | Member | Material | Notes | Image |
| Hiascoactinus | H. boryeongensis | A redfieldiiform actinopterygian.[25] |  | |||
| Megalomatia | M. minima | A basal actinopterygian.[26] | ||||
References
- ↑ Jeon, Heejin; Cho, Moonsup; Kim, Hyeoncheol; Horie, Kenji; Hidaka, Hiroshi (September 2007). "Early Archean to Middle Jurassic Evolution of the Korean Peninsula and Its Correlation with Chinese Cratons: SHRIMP U-Pb Zircon Age Constraints". The Journal of Geology. 115 (5): 525–539. Bibcode:2007JG....115..525J. doi:10.1086/519776. ISSN 0022-1376.
- ↑ Egawa, Kosuke; Lee, Yong Il (10 July 2009). "Jurassic synorogenic basin filling in western Korea: sedimentary response to inception of the western Circum-Pacific orogeny". Basin Research. 21 (4): 407–431. Bibcode:2009BasR...21..407E. doi:10.1111/j.1365-2117.2009.00408.x. ISSN 1365-2117.
- ↑ Kim, Jong Heon; Kimura, Tatsuaki (1988). "Lobatannularia nampoensis (Kawasaki) Kawasaki from the Upper Triassic Baegunsa Formation, Nampo Group, Korea". Proceedings of the Japan Academy, Series B. 64 (8): 221–224. Bibcode:1988PJAB...64..221K. doi:10.2183/pjab.64.221.
- 1 2 Kim, Jong-Heon; Lee, Gui-Hyeong (2015). "Fossil Conchostraca from the Amisan Formation of the Nampo Group, Korea". Journal of the Korean Earth Science Society. 36 (2): 181–189. doi:10.5467/JKESS.2015.36.2.181.
- 1 2 Park, Tae-Yoon S.; Kim, Do-Yoon; Nam, Gi-Soo; Lee, Mirinae (2022). "A new titanopteran Magnatitan jongheoni n. gen. n. sp. from southwestern Korean Peninsula". Journal of Paleontology. 96 (5): 1111–1118. Bibcode:2022JPal...96.1111P. doi:10.1017/jpa.2022.30. ISSN 0022-3360.
- 1 2 Jouault, C.; Nam, Gi-Soo; Nel, A. (2023-09-02). "Koreaphlebia gen. nov. (Odonatoptera: Triadophlebiomorpha): new evidence of a Triassic age for the Amisan Formation in Korea". Historical Biology. 35 (9): 1551–1555. Bibcode:2023HBio...35.1551J. doi:10.1080/08912963.2022.2102492. ISSN 0891-2963.
- 1 2 3 4 5 6 7 8 Kimura, Tatsuaki; Kim, Bong-Kyun (1984). "Geological Age of the Daedong Flora in the Korean Peninsula and its Phytogeographical Significance in Asia". Proceedings of the Japan Academy, Series B. 60 (9): 337–340. Bibcode:1984PJAB...60..337K. doi:10.2183/pjab.60.337.
- ↑ Kim, Jong-Heon; Roh, Heon-Sun (2008). "Organ Fossils of Neocalamites carrerei from the Amisan Formation of the Nampo Group, Korea". Journal of the Korean Earth Science Society. 29 (6): 466–473. doi:10.5467/JKESS.2008.29.6.466.
- ↑ Tatsuaki, Kimura; Kim, Bong-Kyun (December 20, 1988). "New taxa in the Late Triassic Daedong Flora, South Korea. Part 1". Transactions and Proceedings of the Palaeontological Society of Japan. 152: 603–624.
- ↑ Kim, Jong-Heon (June 1990). "Three new Equisetites species found from the Upper Triassic Amisan Formation, Nampo Group, Korea". Journal of the Paleontological Society of Korea. 6 (1): 91–99.
- 1 2 3 4 Kim, Jongheon (1 June 2001). "New fossil plants from the Nampo Group (Lower Mesozoic), Korea". Geosciences Journal. 5 (2): 173–180. Bibcode:2001GescJ...5..173K. doi:10.1007/BF02910423. ISSN 1598-7477.
- ↑ Kim, Jong-Heon (2013). "Weltrichia sp. from the Late Triassic Amisan Formation of Nampo Group, Korea". Journal of the Korean Earth Science Society. 34 (5): 402–406. doi:10.5467/JKESS.2013.34.5.402.
- ↑ Kim, Jong-Heon (2009). "Species Diversity and Leaf Form of Ginkgoaleans from the Mesozoic and Cenozoic Strata in Korea". Journal of the Korean Earth Science Society. 30 (1): 1–9. doi:10.5467/JKESS.2009.30.1.001.
- ↑ Kim, Jong-Heon; Kim, Hee-Soo; Lee, Bong-Jae; Kim, Jung-Min; Lee, Hee-Kwon (2002). "A New Species of Leptostrobus from the Upper Triassic Amisan Formation of the Nampo Group in Korea". Journal of the Korean Earth Science Society. 23 (1): 30–37.
- ↑ Kim, Jong Heon; Lee, Chin Kyu; Choi, Dong Yeol (2015). "Margaritifera cf. isfarensis (Chernishev) from the Amisan Formation, Nampo Group, Korea". Journal of the Geological Society of Korea. 51 (4): 357–362. doi:10.14770/jgsk.2015.51.4.357.
- ↑ Kye Soo, Nam; Jong-Heon, Kim (2014). "Occurrence of the Fossil Mesopsyche dobrokhotovae in the Late Triassic Amisan Formation, Nampo Group, Korea and its Geological Implication". Journal of the Korean Earth Science Society. 35 (3): 161–167. doi:10.5467/JKESS.2014.35.3.161.
- ↑ Lian, X.-N.; Zhang, Y.; Cai, C.-Y.; Feng, Z.; Huang, D.-Y. (2024). "A new genus of Mesopsychidae from the late Middle Triassic Tongchuan entomofauna and its taxonomic and palaeogeographic implications". Mesozoic. 1 (2): 144–158. doi:10.11646/mesozoic.1.2.7.
- ↑ Jouault, Corentin; Lian, Xin-Neng; Nam, Gi-Soo (31 October 2025). "Redescription of the only known Korean specimen of Turbidapsyche dobrokhotovae (Novokshonov, 1997) from the Amisan Formation". Palaeoentomology. 8 (5): 480–482. doi:10.11646/palaeoentomology.8.5.3.
- ↑ Nam, Kye Soo (2017). "Taxonomy and Ecological Implications of Stonefly (Order: Plecoptera) Nymphs from the Late Triassic Amisan Formation in the Boryeong region, Korea". Journal of the Korean Earth Science Society. 38 (4): 293–302. doi:10.5467/JKESS.2017.38.4.293.
- ↑ Nam, Kye Soo; Wang, Ying; Ren, Dong; Kim, Jong Heon; Szwedo, Jacek (18 January 2017). "An extraordinary palaeontinid from the Triassic of Korea and its significance". Scientific Reports. 7 (1): 40691. doi:10.1038/srep4069 (inactive 11 July 2025). ISSN 2045-2322.
{{cite journal}}: CS1 maint: DOI inactive as of July 2025 (link) - ↑ Nel, André; Nam, Gi-Soo; Jouault, Corentin (2022-09-03). "The first Dysmorphoptilidae (Hemiptera: Cicadomorpha) from the Upper Triassic of South Korea". Annales de la Société Entomologique de France. Nouvelle Série. 58 (5): 455–460. doi:10.1080/00379271.2022.2124191. ISSN 0037-9271.
- ↑ Jouault, Corentin; Nam, Gi-Soo; Boderau, Mathieu; Kwon, Seung-Hyuk; Nel, André (2024-02-27). "A new Triassic Tettigarctidae (Insecta, Hemiptera) from the Amisan Formation (Republic of Korea)". Palaeoentomology. 7 (1): 132–140. doi:10.11646/palaeoentomology.7.1.9. ISSN 2624-2834.
- 1 2 Nel, André; Nam, Gi-Soo; Jouault, Corentin (2 October 2022). "First representative of the odonatan superfamily Triassolestoidea (Odonatoptera: Parazygoptera) from the Upper Triassic of the Korean Peninsula". Alcheringa: An Australasian Journal of Palaeontology. 46 (3–4): 237–243. doi:10.1080/03115518.2022.2130426.
- ↑ Jouault, Corentin; Nam, Gi-Soo; Nel, André (2022-10-01). "The first Geinitziidae (Polyneoptera: Reculida) from the Upper Triassic Amisan Formation of South Korea". Annales de Paléontologie. 108 (4) 102558. Bibcode:2022AnPal.10802558J. doi:10.1016/j.annpal.2022.102558. ISSN 0753-3969.
- ↑ Kim, Su-Hwan; Lee, Yuong-Nam; Park, Jin-Young; Lee, Sungjin; Lee, Hang-Jae (2020-04-01). "The first record of redfieldiiform fish (Actinopterygii) from the Upper Triassic of Korea: Implications for paleobiology and paleobiogeography of Redfieldiiformes". Gondwana Research. 80: 275–284. Bibcode:2020GondR..80..275K. doi:10.1016/j.gr.2019.11.008. ISSN 1342-937X.
- ↑ Kim, Su-Hwan; Lee, Yuong-Nam; Nam, Gi-Soo; Park, Jin-Young; Lee, Sungjin; Son, Minyoung (2024-01-03). "A new exceptionally well-preserved basal actinopterygian fish in the juvenile stage from the Upper Triassic Amisan Formation of South Korea". Scientific Reports. 14 (1): 317. Bibcode:2024NatSR..14..317K. doi:10.1038/s41598-023-50803-z. ISSN 2045-2322. PMC 10764774. PMID 38172381.