Tahora Formation

Tahora Formation
Stratigraphic range: Campanian
Type Geological formation
Unit of Tinui Group
Sub-units Maungataniwha Sandstone Member, Mutuera Member, Houpapa Member
Underlies Whangai Formation
Overlies Urewera Group or Matawai Group
Thickness ~500 m (1,600 ft)[1]
Lithology
Primary Sandstone, conglomerate
Other Siltstone
Location
Coordinates 39°00′S 176°48′E / 39.0°S 176.8°E / -39.0; 176.8Coordinates: 39°00′S 176°48′E / 39.0°S 176.8°E / -39.0; 176.8
Approximate paleocoordinates 59°24′S 168°48′W / 59.4°S 168.8°W / -59.4; -168.8
Region North Island
Country  New Zealand
Extent Gisborne
Type section
Named for Tahora Station

The Tahora Formation is a Late Cretaceous geologic formation that outcrops in northeastern New Zealand near Gisborne.[2][3] It is Haumurian in age according to the New Zealand geologic time scale (mainly Campanian, but ranging from Santonian to lower Maastrichtian). It forms part of the Upper Cretaceous to Teurian (Danian) (lower Paleocene) Tinui Group. It unconformably overlies the Jurassic to Lower Cretaceous Urewera Group or the Upper Cretaceous Matawai Group. It is conformably overlain by the Haumurian to Teurian Whangai Formation. It consist of three members, the Maungataniwha Sandstone Member, the Mutuera Member and the Houpapa Member.[1] It is named for Tahora Station, south of Matawai in the Gisborne Region. The aptly named Maungataniwha (Māori for "mountain of monsters") Sandstone Member is known for its rich reptile fossil remains, first investigated by amateur palaeontologist Joan Wiffen.

Depositional environment

The whole of the Tinui Group is interpreted to be an upper Cretaceous transgressive sequence. The Maungataniwha Sandstone Member was deposited in a very shallow water to beach environment. The siltstones of the time-equivalent Mutuera Member are thought to have been deposited in a mid to outer shelf environment. The Houpapa Member is interpreted to be the fill of local channels cut into the underlying strata.[1]

Fossil content

Vertebrates

Indeterminate dinosaur remains have been recovered from the formation, including indeterminate theropod, titanosaur, nodosaurid, and hypsilophodont remains.[4] Other fossils found in the Tahora Formation are of the 40 foot long mosasaur Moanasaurus and Rikkisaurus. The humerus of a pterosaur very similar to the Australian Mythunga has also been found.

Invertebrates

Invertebrates found in the formation include beetles,[5] ammonites, annelids, belemnites, bivalves, brachiopods, crinoids, crustaceans, gastropods, nautiloids and scaphopods.[3]

See also

References

  1. 1 2 3 Isaac M.J., Moore P.R. & Joass Y.J. (1991). "Tahora Formation: The basal facies of a Late Cretaceous transgressive sequence, northeastern New Zealand". New Zealand Journal of Geology and Geophysics. 34 (2): 227–236. doi:10.1080/00288306.1991.9514460.
  2. ↑ "Tahora Formation". New Zealand Stratigraphic Lexicon. GNS Science. Retrieved 25 May 2013.
  3. 1 2 Vajda V. & Raine J.I. (2010). "A palynological investigation of plesiosaur-bearing rocks from the Upper Cretaceous Tahora Formation, Mangahouanga, New Zealand" (PDF). Alcheringa. 34: 359–374. doi:10.1080/03115518.2010.486642.
  4. ↑ Weishampel, et al. (2004). "Dinosaur distribution" Pp. 517-607. in Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. 861 pp. ISBN 0-520-24209-2. " Pp. 517-607.
  5. ↑ GS 14182, Mangahouanga Stream (V19/f133) at Fossilworks.org
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