Geoncheonri Formation
| Geoncheonri Formation | |
|---|---|
| Stratigraphic range: ~ | |
 | |
| Type | Geological formation |
| Unit of | Hayang Group |
| Underlies | Yucheon Group Jusasan Formation (volcanics) |
| Overlies | Chaeyaksan Formation (volcanics) |
| Thickness | Up to 2,000m |
| Lithology | |
| Primary | Mudstone |
| Other | Siltstone |
| Location | |
| Coordinates | 35°54′N 128°36′E / 35.9°N 128.6°E |
| Approximate paleocoordinates | 45°12′N 122°42′E / 45.2°N 122.7°E |
| Region | Daegu, Gyeongsangbuk-do, Gyeongsangnam-do |
| Country | South Korea |
| Extent | Gyeongsang Basin |
  Geoncheonri Formation (South Korea) | |
The Geoncheonri Formation (Korean: 건천리층; Hanja: 乾川里層; RR: Geoncheolli-cheung) is an Upper Cretaceous (Turonian-Santonian) geologic formation of the Hayang Group in the Gyeongsang Basin of southeast South Korea.[1] Fossil ornithopod tracks,[2] as well as fossils of Kirgizemys have been reported from the lacustrine siltstones and mudstones of the formation.[3]
Geology
[edit]The Geoncheonri Formation (ca. 800 metres (2,600 ft) thick) is the uppermost formation of the Hayang Group in the Uiseong Subbasin, belonging to the Gyeongsang Supergroup. It correlates with the upper part of the Jindong Formation of the Milyang Subbasin. The depositional environment of the Geonchonri Formation has been interpreted as shallow lacustrine settings, consists of mudstones, siltstones and fine-to medium grained sandstones.
The age of the Geonchonri Formation has been disputed for decades. Plant fossils from the Geoncheonri Formation were correlated with the Monobegawa Group and the Gyliak Series (Lower to "Middle" Cretaceous) in Japan. Yang (1978) noted that the co-occurrence of a bivalve Trigonioides paucisulcatus in the Geonchonri Formation and in the Goshonoura Group (Cenomanian to Turonian) of Japan.[4] However, primitive angiosperm pollen (Retimonocolpites peroreticulatus and Tricolpites sp.) and other palynological features suggest that the age of the Geoncheonri Formation is Aptian to Albian. The charophytes from the Geoncheonri Formation suggested an Aptian to Albian in age. Whereas the underlying Chaeyaksan Basalt dates back to 94 ± 3 Ma,[5] and the Rb-Sr age dating suggests that the age of the overlying Jusasan Andesite is 83.6 Ma.[5] Moreover, based on ostracod fossils, Choi and Wang (2024) suggested the depositional age of the Geonchonri Formation dates back to Late Cretaceous, especially Turonian to Santonian, probably up to Campanian.[6]
Fossil content
[edit]The following fossils were reported from the formation:[1]
- Turtles
- Ostracods[7]
- Cypridea sp.
- Lycopterocypris cf. profunda
- Cypria cf. elata
- Ichnofossils
See also
[edit]References
[edit]- 1 2 Geoncheonri Formation in the Paleobiology Database
- ↑ Weishampel, David B.; Dodson, Peter; Osmólska, Halszka (2004), The Dinosauria, 2nd edition, Berkeley: University of California Press, pp. 1–880, ISBN 0-520-24209-2, retrieved 2019-02-21
{{citation}}: CS1 maint: publisher location (link) - 1 2 Lee, Y.-N.; Hutchison, J. H.; Chang, K.-H. (2009), "The first Mesozoic turtle from South Korea", Cretaceous Research, 30 (5): 1287–1292, Bibcode:2009CrRes..30.1287L, doi:10.1016/j.cretres.2009.07.004
- ↑ Yang, Seong Young (30 June 1978). "On the discovery of Nippononaia ryosekiana from the Gyeongsang Group, Korea". Journal of the Geological Society of Korea. 14 (2): 33–43. doi:10.14770/jgsk.1978.14.2.33.
- 1 2 Kang, Hee-Cheol; Kim, In-Soo; Yun, Sung-Hyo (2000). "Palaeomagnetic study on the Cretaceous rocks in the Konchonri area of the Northern Milyang Subbasin, Korea" (PDF). Journal of the Korean Geophysical Society. 3 (1): 1–12.
- ↑ Choi, Byung-Do; Wang, Yaqiong (3 April 2025). "Non-marine ostracods from the Cretaceous Banyaweol and Geoncheonri formations (Gyeongsang Basin, Korea) in the collections of the Geological Museum, KIGAM: Taxonomy, biostratigraphy, palaeobiogeography and palaeoenvironment". Historical Biology. 37 (4): 933–949. doi:10.1080/08912963.2024.2341858.
- ↑ Choi, Byung-Do; Wang, Yaqiong (2025). "Cretaceous non-marine ostracod faunas of South Korea: Synthesis of taxonomy, biostratigraphy and paleoecology". Cretaceous Research. 168. 106070. doi:10.1016/j.cretres.2024.106070.
- 1 2 Lee, Y.-N.; Yu, K.-M.; Wood, C. B. (2001), "A review of vertebrate faunas from the Gyeongsang Supergroup (Cretaceous) in South Korea", Palaeogeography, Palaeoclimatology, Palaeoecology, 165 (3–4): 357–373, Bibcode:2001PPP...165..357L, doi:10.1016/S0031-0182(00)00171-1