TheWanganui Basin (also spelledWhanganui Basin) is an onshore-offshore basin on the North Island ofNew Zealand. The basin provides an important stratigraphic and palaeontological record of the late Neogene marine environment of New Zealand.[1][2][3]
The Wanganui Basin is located on the west coast of theNorth Island of New Zealand, within theManawatū-Whanganui andTaranaki regions. The basin is roughly oval, with the longer (approximately 180 kilometres (110 miles)) axis running west-south-west/east-north-east, and has a width of approximately 100 kilometres (62 miles). A little under half of the basin is onshore, extending inland around the lower reaches of theWhanganui andRangitikei Rivers before terminating at the foot of theNorth Island Volcanic Plateau. The southern half of the basin extends into theSouth Taranaki Bight. The major population centre within the basin is along the coast, around the city ofWhanganui.
The Wanganui Basin is "one of the most complete late Neogene marine stratigraphic records in the world,"[1] and is an important region for geological and palaeontological research.[2][3]
The basin provides the basis for the eponymousWanganui epoch in theNew Zealand geologic time scale, which covers thePliocene,Pleistocene andHolocene over the last 5.33 million years.[1][4] The series was first described in depth and compared toglacial cycles byCharles Fleming,[3][5] which has had a lasting impact upon subsequent stratigraphic, palaeontological and palaeoecological research.[2] Each stage within the Wanganui epoch is named after regions of the Wanganui Basin series.[4]
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Sediments within the basin are rich with shallow marine invertebrate fossils, includingmolluscs[5] andbryozoans.[6] The most common fossilized molluscan shells belong to the bivalve generaDosinia andChlamys and the gastropod generaZethalia andMurex.[3] Shells ofAeneator,Buccinulum,Penion,Alcithoe, andAmalda marine snails are also frequent.[5]