Further Comments on the Southwest Pacific Paleogene Regional Unconformities

Edwards, Anthony

doi:10.2973/dsdp.proc.30.122.1975

Cited by 4 publications

(2 citation statements)

References 8 publications

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“…Further evidence that Muzzle Group unconformities are due primarily to current regimes rather than sea-level changes is found in DSDP cores from the Lord Howe Rise, north Tasman Sea (Burns et al 1973). In this region, quite the opposite pattern of sedimentation is recorded, with a regional unconformity coinciding with peak warming in the latest Paleocene and early Eocene (Edwards 1973(Edwards ,1975. Does this signal an intensification of subtropical current flow over the Lord Howe Rise in response to extreme warming in the early Cenozoic?…”

Section: Discussionmentioning

confidence: 99%

Biostratigraphy and carbon isotope stratigraphy of uppermost Cretaceous‐lower Cenozoic Muzzle Group in middle Clarence valley, New Zealand

Hollis

Fielding

Jones

et al. 2005

Journal of the Royal Society of New Zealand

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Muzzle Group strata exposed along southeast-flowing tributaries of the Clarence River valley, Marlborough, record hemipelagic-pelagic sedimentation across a high latitude (c. 55°S), terrigenous sediment-starved, continental margin from latest Cretaceous to middle Eocene times. Studies of dinoflagellates, foraminifera, calcareous nannofossils, and radiolarians have been integrated with bulk carbonate δ 13 C profiles to establish the chronostratigraphy for two stratigraphic sections along Bluff and Muzzle Streams, middle Clarence valley. The two sections comprise similar successions. Uppermost Cretaceous (upper Haumurian) micritic limestone of Mead Hill Formation is overlain unconformably by Teredo Limestone, a c. 0.25 m thick bed of highly glauconitic, calcareous sandstone. This unit, the basal member of Amuri Limestone, is overlain conformably by c. 15 m thick Lower Limestone, micritic limestone that is glauconitic at base and progressively more marl-rich in its upper part. Lower Limestone grades up into Lower Marl, a poorly exposed, 40-70 m thick unit of alternating marl and micritic limestone beds. Biostratigraphy indicates that the base of Amuri Limestone is younger at Bluff Stream (earliest Eocene, early Waipawan) than at Muzzle Stream (late Paleocene, late Teurian). In the condensed (12 m) upper Paleocene-lower Eocene Amuri Limestone sequence at Muzzle Stream, a trend in δ 13 C from high ( 2.4‰) to low ( 1‰) values is consistent with global records across three major climate or carbon cycle perturbations: the late Paleocene carbon isotope maximum (PCIM, 59-56 Ma), the initial Eocene thermal maximum (IETM, 55.5 Ma), and the early Eocene climatic optimum (EECO,. Probably only the upper PCIM is preserved in the 4 m thick siliceous limestone interval overlying Teredo Limestone. The IETM is well-defined by a 1‰ negative δ 13 C excursion at the base of a 0.8 m thick marl-rich unit (Dee Marl), 5 m above the base of Lower Limestone at Muzzle Stream, and the abrupt appearances of Eocene-restricted species or distinctly warm-water elements within dinoflagellate, foraminiferal, calcareous nannofossil, and radiolarian assemblages. The lithological expression of the IETM as a recessive marly unit has now been identified in three Clarence valley sections (Muzzle, Dee, and Mead Streams), representing a 20 km continental margin transect. Sedimentation rate trends across this margin indicate that the local effects of extreme global warming were increased supply of terrigenous mud, probably due to enhanced precipitation, weathering and erosion, and a decrease in pelagic sedimentation, reflecting a decrease in oceanic productivity. Bluff section lacks an IETM record but contains an expanded (20 m) early Eocene succession that records the onset of the EECO as a progressive

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Section: Discussionmentioning

confidence: 99%

Biostratigraphy and carbon isotope stratigraphy of uppermost Cretaceous‐lower Cenozoic Muzzle Group in middle Clarence valley, New Zealand

Hollis

Fielding

Jones

et al. 2005

Journal of the Royal Society of New Zealand

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“…Initial reports for DSDP Legs 21 and 29 (Burns and Andrews, 1973;Kennett et al, 1975) laid foundations for understanding the interplay between tectonic and oceanographic events in the region, including opening of the Tasman Sea and separation of Australia and New Zealand from Antarctica (Andrews et al, 1975;Andrews and Ovenshine, 1975;Edwards, 1973Edwards, , 1975Kennett et al, 1975;Kennett and Shackleton, 1976). Stable isotope records from DSDP Leg 29 (Sites 277 and 278) reveal a general cooling trend from warm to cool temperate conditions, with evidence for a pronounced cooling step across the Eocene-Oligocene transition.…”

Section: Post-eocene Climate Evolutionmentioning

confidence: 99%

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Sutherland¹,

Dickens²,

Blum³

2016

International Ocean Discovery Program Scientific Prospectus

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Allostratigraphy of coastal south and east Otago: A stratigraphic framework for interpretation of the Great South Basin, New Zealand

McMillan

Wilson

1997

New Zealand Journal of Geology and Geophysics

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Sixteen unconformities, some with correlative conformities, are recognised within the Late CretaceousTertiary transgressive-regressive sediments of coastal Otago. These provide the basis for stratigraphic division and correlation with seismic reflectors in the offshore ageequivalent sediments of the Great South Basin. The ages of the unconformities/conformities are constrained mainly by dinoflagellate biostratigraphy, but foraminiferal biostratigraphy is important for the Oligocene-Miocene. In terms of current biozone-stage correlation, the 16 unconformities comprise the following: two intra-Haumurian (Late Cretaceous) unconformities, one at the K/T boundary, three intra-Teurian (Paleocene) unconformities, two of early Waipawan age, two of late Mangaorapan -early Heretaungan age, a late Heretaungan unconformity, a late Porangan -early Bortonian unconformity, a late Bortonian unconformity (a total of seven Eocene unconformities), a late Runangan -early Whaingaroan unconformity, a late Whaingaroan unconformity (both Oligocene), and a midWaitakian (Miocene) unconformity. Other, early-midCretaceous unconformities are inferred from offshore seismic profiles. Six unconformities/correlative conformities in onland Otago provide the basis for recognising four informal alloformations.

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Further Comments on the Southwest Pacific Paleogene Regional Unconformities

Cited by 4 publications

References 8 publications

Biostratigraphy and carbon isotope stratigraphy of uppermost Cretaceous‐lower Cenozoic Muzzle Group in middle Clarence valley, New Zealand

Biostratigraphy and carbon isotope stratigraphy of uppermost Cretaceous‐lower Cenozoic Muzzle Group in middle Clarence valley, New Zealand

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Allostratigraphy of coastal south and east Otago: A stratigraphic framework for interpretation of the Great South Basin, New Zealand

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