Geoncheonri Formation

Geoncheonri Formation Stratigraphic range: Albian ~112–100 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Type	Geological formation
Unit of
Underlies	(volcanics)
Overlies	(volcanics)
Thickness	Up to 800 m (2,600 ft)
Lithology
Primary	Mudstone
Other	Siltstone
Location
Coordinates	35°54′N 128°36′E / 35.9°N 128.6°E / 35.9; 128.6Coordinates: 35°54′N 128°36′E / 35.9°N 128.6°E / 35.9; 128.6
Approximate paleocoordinates	45°12′N 122°42′E / 45.2°N 122.7°E / 45.2; 122.7
Region	Daegu, Gyeongsangbuk-do, Gyeongsangnam-do
Country	South Korea
Extent
Geoncheonri Formation (South Korea)

The Geoncheonri Formation is an Early Cretaceous (Aptian-Albian) geologic formation of the in the 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]

Description[]

The Geoncheonri Formation (ca. 800 metres (2,600 ft) thick) is the uppermost formation of the , belonging to the . The Gyeongsang Supergroup is widely distributed in the southeastern part of the Korean Peninsula, mainly within the , which is the largest sedimentary basin of South Korea. It is divided into the Shindong and Hayang Groups, consisting mainly of thick siliciclastic sequences of alluvial, fluvial and lacustrine sediments, and the , characterized by the dominance of volcanic rocks.^[4]

The Hayang Group consists of Chilgok, , , Haman, , , and Geoncheonri Formations in ascending order. The Geoncheonri Formation is conformably underlain by the and overlain by the , the lowermost of the Yucheon Group.^[4]

Since plant fossils were first reported in the Geoncheonri Formation in 1925, a series of paleontological studies has been made with molluscs, spores and pollen, charophytes, and dinosaur footprints. Plant fossils from the Geoncheonri Formation were correlated with the and the (Lower to "Middle" Cretaceous) in Japan. Yang (1978) noted that the co-occurrence of a pelecypod in the Geonchonri Formation and in the Gyliakian (Cenomanian to Turonian) of Japan. However, primitive angiosperm pollen ( and sp.) and other palynological features suggest that the age of the Geoncheonri Formation is Aptian to Albian. The charophytes from the Geoncheonri Formation also indicate an Aptian to Albian age.^[4]

Fossil content[]

The following fossils were reported from the formation:^[1]

• Turtles
  • Kirgizemys cf. exaratus^[3]
• Ichnofossils
  • Ornithopoda indet.^[5]
  • Theropoda indet.^[5]

See also[]

• List of dinosaur-bearing rock formations
  • List of stratigraphic units with ornithischian tracks
    • Ornithopod tracks
• Gugyedong Formation
• Haman Formation
• Hasandong Formation
• Jinju Formation
• Sagog Formation

References[]

Bibliography[]

• Lee, Y.-N.; J. H. Hutchison, and K.-H. Chang. 2009. The first Mesozoic turtle from South Korea. Cretaceous Research 30. 1287–1292.
• Weishampel, David B.; Peter Dodson, and Halszka (eds.) Osmólska. 2004. The Dinosauria, 2nd edition, 1–880. Berkeley: University of California Press. Accessed 2019-02-21. ISBN 0-520-24209-2
• Lee, Y.-N.; K.-M. Yu, and C. B. Wood. 2001. A review of vertebrate faunas from the Gyeongsang Supergroup (Cretaceous) in South Korea. Palaeogeography, Palaeoclimatology, Palaeoecology 165. 357–373.