Kokoamu Greensand

The Kokoamu Greensand is a geological formation found in New Zealand. It is a fossil-bearing, late Oligocene, greensand rock unit of the eastern South Island, especially the Waitaki District of North Otago and the southern Canterbury region. The formation was named by geologist Maxwell Gage in the 1950s. In North Otago it underlies the thicker and harder Otekaike Limestone.[1] The formation gets its green colour from the mineral glauconite which forms slowly on the ocean floor.

Kokoamu Greensand Stratigraphic range: Chattian ~27.3–25.2 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Type	Geological formation
Unit of	Otiake Group
Underlies	Otekaike Limestone
Overlies	Earthquakes Marl
Thickness	up to 7 metres (20 ft)
Lithology
Primary	Greensand
Other	Limestone
Location
Coordinates	44.7°S 170.5°E
Approximate paleocoordinates	50.5°S 176.3°W
Region	Canterbury, Otago
Country	New Zealand
Extent	Around Duntroon, South Island
Kokoamu Greensand (New Zealand)

Fossil content

The formation was laid down in shallow seas some 26-30 million years ago. It contains abundant microfossils of foraminifera, ostracods and coccoliths, those of larger marine invertebrates such as the shells of brachiopods, gastropods and scallops, as well as corals, echinoderms, and crustaceans. Vertebrates found in the formation include fish, penguins and cetaceans. Many of the fossils discovered in the formation are held in the Geology Museum of the University of Otago.[1]

Penguins

• Archaeospheniscus lopdelli, A. lowei[2][3]
• Duntroonornis parvus[3]
• Kairuku waitaki, K. grebneffi[4][5]
• Korora oliveri[6]
• Manu antiquus[3]
• Palaeeudyptes[3]
• Platydyptes amiesi, P. marplesi, P. novaezealandiae[6][3]

Cetaceans

• Awamokoa tokarahi[7]
• Horopeta
• Mammalodon hakataramea[8]
• Matapanui waihao[9]
• Tohoraata waitakiensis[3]
• Tokarahia lophocephalus[3]
• Whakakai waipata[10]

See also

• Geology of Canterbury, New Zealand

References

1. Fordyce, R. Ewan. "The Kokoamu Greensand – Late Oligocene, New Zealand". Geological Settings. Department of Geology, University of Otago. Retrieved 2012-02-29.
2. Maerewhenua at Fossilworks.org
3. Duntroon at Fossilworks.org
4. J40/f190 - Waihao River at Fossilworks.org
5. Waipati Creek at Fossilworks.org
6. Hakataramea Valley at Fossilworks.org
7. Tokarahi Cliff at Fossilworks.org
8. Haughs Quarry at Fossilworks.org
9. J40/f70 - Waihao River at Fossilworks.org
10. The Earthquakes at Fossilworks.org

Further reading

• R. W. Boessenecker and R. E. Fordyce. 2016. A new eomysticetid from the Oligocene Kokoamu Greensand of New Zealand and a review of the Eomysticetidae (Mammalia, Cetacea). Journal of Systematic Palaeontology
• R. E. Fordyce. 2002. Oligocene origins of skim-feeding right whales: A small archaic balaenid from New Zealand. Journal of Vertebrate Paleontology 22(3):54A
• D. T. Ksepka, R. E. Fordyce, T. Ando and C. M. Jones. 2012. New fossil penguins (Aves, Sphenisciformes) from the Oligocene of New Zealand reveal the skeletal plan of stem penguins. Journal of Vertebrate Paleontology 32(2):235-254
• D. MacKinnon, S. S. Beus, and D.L. Lee. 1993. Brachiopod fauna of the Kokoamu Greensand (Oligocene), New Zealand. New Zealand Journal of Geology and Geophysics 36:327-347
• B. J. Marples. 1956. Cetotheres (Cetacea) from the Oligocene of New Zealand. Proceedings of the Zoological Society of London 126(4):565-580
• Y. Tanaka and R. E. Fordyce. 2016. Awamokoa tokarahi, a new basal dolphin in the Platanistoidea (late Oligocene, New Zealand). Journal of Systematic Palaeontology
• C. H. Tsai and R. E. Fordyce. 2016. Archaic baleen whale from the Kokoamu Greensand: earbones distinguish a new late Oligocene mysticete (Cetacea: Mysticeti) from New Zealand. Journal of the Royal Society of New Zealand