The basement geology and palaeontology of the Wairaki Hills, Southland.
Begg, John Graham
Lithologic and biostratigraphic mapping of the Wairaki Hills was commenced to provide detailed geologic maps on which to base data subsequently derived from palaeontological study. Faunas found were collected quickly during mapping and field determinations were noted. Some rich localities were collected more thoroughly in later visits. The geologic age range of the rocks was found to be Makarewan (?Djulfian-Dorashamian} to Oretian (?late Carnian), with a break in deposition between the latest Permian and earliest Triassic (i.e. Dorashamian-Smithian). In the laboratory, collections gathered in the field, as well as collections gathered by others previously, were prepared and all secure taxa available were described and drawn. The process resulted in identification of at least 17 new genera, perhaps as many as 22, as well as a plethora of undescribed species. Recognition of foraminiferids and ostracods within the sediments opens new fields of study in New Zealand Triassic fossils. Other important finds include productinids and a crassatellid from the Wairaki Formation, Eophyllites from the Malakovian (Smithian) and a nautiloid, cidaroid, buchiid, beyrichitid, cirriped and trigonioid from the Etalian Stage (Anisian). The faunas are regarded as marine, shallow shelf forms (probably mostly above wave base) and most collections are regarded as essentially in situ assemblages. After collation of data on biostratigraphy, informal stage definitions were attempted and successfully used; the base of the Makarewan Stage was drawn at the first appearance of Wairakiella rostrata at the type locality, the Malakovian Stage base at the first appearance of Owenites, and the Etalian at the first appearance of Mellarium at the type locality. Correlation with other New Zealand rocks of equivalent age is made as well as an attempt at correlation with important world faunas and sequences of equivalent age. The Makarewan Stage is correlated with the Djulfian-Dorashamian Stages of the world standard, the Malakoyian with the late Smithian Stage and the Etalian with the Varium Zone of the Anisian Stage. The need for a more refined zonal scheme; for New Zealand Triassic rocks is acknowledged and the systematic palaeontology section of this thesis is regarded as a necessary preliminary step in establishment of such a scheme.
Advisor: Campbell, John Douglas
Degree Name: Doctor of Philosophy
Degree Discipline: Geology
Publisher: University of Otago
Research Type: Thesis