The Amisan Formation (Korean: 아미산층) is an Late Triassic geologic formation in 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 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]
^ abcdefghKimura, 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.
^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.