An Eocene to early Oligocene unconformity‐bounded sequence in the Punakaiki‐Westport area, West Coast, South Island, New Zealand

Lever, Helen

doi:10.1080/00288306.2001.9514944

Cited by 6 publications

(23 citation statements)

References 13 publications

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“…In the Punakaiki to Fox River (Fig. 4: 5) area, there is no evidence of an unconformity between Arnold and Landon Series sediments, but there is an unconformity probably within the lower Whaingaroan (Lever 2001) that appears to be associated with abrupt shallowing, rhodolith formation, karst development, and erosion. This unconformity is then overlain by Nile Group Limestone, which contains a local paraconformity (probably Whaingaroan-Duntroonian) exposed at Dolomite Point, consisting of phosphatic nodules and quartz granules (Laird 1988).…”

Section: Successions Containing One Oligocene Unconformitymentioning

confidence: 99%

“…Here, the boundary between Arnold and Landon Series is conformable, occurring within the topmost beds of the Kaiata Formation. The boundary between the Kaiata Formation and the Little Totara Sand is a marked disconformity, with evidence of up to 4 m of erosion (Lever 2001), as well as rapid shallowing before the erosion and subsequent deposition of lagoonal muds and sands occurred. The Little Totara Sand has not been dated (it is unfossiliferous) but it is overlain by the Waitakere Limestone (correlated with Duntroonian Stage limestones elsewhere).…”

Section: Successions Containing One Oligocene Unconformitymentioning

confidence: 99%

“…The Westland basins were, however, definitely tectonically active during the Eocene and Oligocene-as shown by the variation in thicknesses and facies of the successions across very short distances (Nathan etal. 1986;Lever 2001).…”

Section: Successions Containing One Oligocene Unconformitymentioning

confidence: 99%

“…Angular unconformities (Lewis 1992), sedimentary dikes (Lewis et al 1979), and folding (e.g., Field et al 1989;Browne 1995) can be found in various mid-Tertiary successions. In addition, the vast differences in thickness of Tertiary sediment accumulated in adjacent sub-basins across the South Island indicate that some kind of differential subsidence and therefore faulting was occurring (e.g., Nathan et al 1986;Lever 2001).…”

Section: Introductionmentioning

confidence: 99%

“…Some unconformities have been linked to sea-level falls, although often the ages of the unconformities do not match the timing of the global falls in sea level, and the cause of the unconformity is therefore assigned to local tectonic movements (e.g., Lever 2001). Correlating a global sea-level chart from Abreu & Anderson (1998) with the New Zealand stages (Fig.…”

Section: Introductionmentioning

confidence: 99%

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Review of unconformities in the late Eocene to early Miocene successions of the South Island, New Zealand: Ages, correlations, and causes

Lever

2007

New Zealand Journal of Geology and Geophysics

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Unconformities are physical surfaces dividing strata of different ages. However, the term is used also to mean the time that is not represented by sediments, or missing time. While unconformities are created by geological events that either prevent deposition or remove deposited sediment, a single unconformity surface could represent multiple events, and if the last event is of sufficient magnitude, the unconformity's appearance will represent the processes occurring only during that event. It should be of no surprise, therefore, that unravelling the history of successions containing multiple unconformities is difficult, and that is especially the case where dating is poor and where unconformity surfaces are hard to correlate.An example of the difficulty presented by unconformable successions can be seen in the Oligocene stratigraphy of New Zealand, where the Marshall Paraconformity has been the focus of controversial interpretation, correlation, and dating. The succession was originally described as conformable, as the unconformities generally (but not always) occur between units orientated parallel to each other. The first location (in Mid Canterbury) where a significant unconformity was identified by biostratigraphy placed the age of the unconformity between early Oligocene sediments and late Oligocene sediments. Other unconformities identified around the South Island in a similar stratigraphic position were correlated with this unconformity. Later dating of a newly designated type section placed the Marshall Paraconformity within the Whaingaroan Stage, in the early Oligocene. Although many biostratigraphic ages for unconformities in South Island successions are not precise, the available data show a distinct range of unconformity ages in different basins. In general, Oligocene deposits are condensed, but there appears to be no one time in the Oligocene when unconformities developed everywhere.Unconformities in the Oligocene could be caused by global sea-level falls, relative sea-level high-stand, local faulting and volcanic activity, and oceanic current activity. These causes could have formed both local and regionally extensive unconformities. In successions with only one unconformity surface, that surface may represent the occurrence of multiple unconformity-causing processes, further complicating the unravelling of Oligocene geologic history in New Zealand.

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Section: Successions Containing One Oligocene Unconformitymentioning

confidence: 99%

Section: Successions Containing One Oligocene Unconformitymentioning

confidence: 99%

Section: Successions Containing One Oligocene Unconformitymentioning

confidence: 99%