Lithostratigraphy and Biostratigraphy of Swinburn; Proxies for Paleogeography from Central Otago Marine Strata


Richards, Marcus


Project type:



The Maniototo Basin preserves localised Cenozoic marine strata that can be correlated into Waitaki Valley, with formation names as used in the southern Canterbury Basin. The clastic-dominated strata were derived from an Otago Schist source on Zealandia during maximum submergence. Long-recognised marine strata from the Maniototo are the Naseby Greensand and Green Valley Limestone. This study recognises formations including: Kauru, Wharekuri (truncated by the Marshall Unconformity), Kokoamu, and Otekaike. The basin-wide greensand resting on the Marshall Unconformity is Kokoamu Formation with an age of Whaingaroan- Duntroonian. The Naseby Greensand of Kyeburn is now identified as a composite of units including Whaingaroan to Waitakian-aged fossils and is equivalent to Wharekuri, Kokoamu and Otekaike Formation. The use of Naseby Formation should be discontinued. Kokonga - Green Valley Limestone is Otekaike equivalent. We now detail a 200 m section at Swinburn, comprising massive fossiliferous marine rocks with a pervasive micaceous, very fine quartz sand to silt component. The sequence is variably (in places richly) glauconitic, grading up through calcareous sandstones to a packstone unconformably overlain by Wedderburn Formation and capped by basaltic volcanics. Foraminifera and ostracods date these units as upper Runangan - lower Whaingaroan to mid-Waitakian; low planktic foraminiferal percentages are consistent with limited oceanic influence. Uncommon fossil scallops (Pectinidae) in the Janupecten - Lentipecten lineage are consistent with microfossil ages. This sequence is thicker, more clastic - dominated, and nearer to sediment source (probably Otago Schist) than in the Waitaki. The background sedimentation of subangular very fine sand and silt found iii throughout the Oligocene indicates a continuous supply from the terrestrial source. A nearby stratigraphically lower sequence includes quartzose coal measures, inferred estuarine mudstones with rare molluscs, and intertidal shales, consistent with a paralic to estuarine setting, and is a correlative of Kauru Formation. The beds show a pattern of marine transgressions and regressions peculiar to this site. Hedecardium indicates a Bortonian to Kaiatan age. In summary, the Swinburn sequence formed in a shallow, possibly early- to mid-Cenozoic epicontinental sea with a productive source of terrigenous clastics. There is no firm evidence of outer shelf settings.

Named Localities:

Thesis description:

xv, 127 pages A4


OU geology Identifier:


Author last name:

OURArchive handle:

OURArchive access level:

Location (WKT, WGS84):

MULTIPOLYGON (((170.326851103521562 -45.144400009853953,170.31041878064002 -45.14458554850502,170.310588624841017 -45.135253224545238,170.32701826354986 -45.135067598840919,170.326851103521562 -45.144400009853953)),((170.386652137944708 -45.161409039434176,170.340630264763689 -45.16072702208109,170.340415834161263 -45.130617162769575,170.388313129141864 -45.130961131131521,170.386652137944708 -45.161409039434176)),((170.277684253347246 -45.012051743114796,170.270162459994538 -45.012062604979292,170.270916171862837 -45.007507655583765,170.27816005784868 -45.00768065677368,170.277684253347246 -45.012051743114796)),((170.304746339913066 -44.979158865655613,170.299651199328224 -44.979038418045057,170.300357342772259 -44.975434835633664,170.304111420823631 -44.975523579779761,170.304746339913066 -44.979158865655613)))




Richards, Marcus, “Lithostratigraphy and Biostratigraphy of Swinburn; Proxies for Paleogeography from Central Otago Marine Strata,” Otago Geology Theses, accessed November 29, 2021,

Output Formats