Taxonomy and Paleoecology of Oligocene Corals from the southern South Island of New Zealand

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Gaffney, Rhian B.J.

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Corals are important components of many marine ecosystems, both modern and ancient. Fossil corals from New Zealand have been reported in Squires’ important 1958 monograph, and more recently by Cairns and others. This research considers the taxonomy and diversity of Oligocene corals from the southern South Island. Fossils were collected from three localities: Hakataramea Quarry and Lake Aviemore in South Canterbury, and Cosy Dell farm in Southland. Corals represent 10 families of alcyonarians and scleractinians: Pennatulidae, Melithaeidae, Oculinidae, Rhizangiidae, Caryophylliidae, Turbinoliidae, Flabellidae, Dendrophyllidae, Poritidae and Astrocoeniidae. In total, the assemblages contain 17 species in 15 genera; they include 6 previously undescribed species of Melithaea, Peponocyathus, Notocyathus, Astrangia, Goniopora and Astrocoenia. Goniopora and Astrocoenia are the first probable hermatypic (reef-forming) coral species of Oligocene age from southern New Zealand. Corals from Hakataramea Valley occur in a glauconitic packstone (Otekaike Limestone), particularly in a high-diversity mid-shelf shellbed (“Protula horizon”). The presence of Stephanocyathus mantelli and Trochocyathus papakurensis suggest average bottom temperatures of 10?C, although warmer temperatures are possible (as indicated by e.g. the brachiopod Lingula and the bivalve Spondylus). Corals from Lake Aviemore, from the richly glauconitic Kokoamu Greensand, are congeneric with those of Hakataramea, despite the different facies. Corals from the Cosy Dell locality are also from highly diverse molluscan-rich strata. The presence of hermatypic coral species at this locality indicates that water temperatures were at minimum 18?C, several degrees warmer than current mean annual sea surface temperatures in southern New Zealand. These hermatypic species must also have lived in the photic zone, and likely lived in waters down to 20-40 m depth. This, the facies and wider assemblage, indicates that the Cosy Dell locality was a shallow inner shelf setting, in comparison to the deeper-water Hakataramea and Aviemore localities.

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143 pages A4

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2016Gaffney

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http://download.otagogeology.org.nz/temp/Abstracts/2016Gaffney.pdf

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Gaffney, Rhian B.J., “Taxonomy and Paleoecology of Oligocene Corals from the southern South Island of New Zealand,” Otago Geology Theses, accessed November 13, 2018, http://theses.otagogeology.org.nz/items/show/630.