Cenozoic Hiatuses in Pelagic Sediments

Moore, Theodore C.; Andel, Tjeerd H. van; Sancetta, Constance; Pisias, Nicklas G

doi:10.2307/1485246

Cited by 171 publications

(72 citation statements)

References 6 publications

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“…Cenozoic global cooling had probably proceeded far enough by about 37 Ma (the Eocene/Oligocene boundary) to permit seasonal sea ice production at the Antarctic margin and a sudden initiation of AABW formation (Kennett and Shackleton, 1976). The invigoration of the thermohaline circulation at this time may have produced a widespread hiatus spanning this boundary (Moore et al, 1978). Recovery was high in both holes (515A, 89%; 515B, 79%), and deformation was low.…”

Section: Site 515mentioning

confidence: 99%

Site 515: Brazil Basin

Barker¹,

Carlson²,

Johnson³

1983

Initial Reports of the Deep Sea Drilling Project

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.10Depth sub-bottom (m): 636.4 Nature: Zeolite-rich calcareous mudstone Age: early Eocene Measured velocity (km/s): 1.87 to 2.14 Principal results: Hole 515 was rotary drilled and washed to 55 m, but the drilling was terminated when the pressure core barrel jammed in the bottom-hole assembly. In Hole 515A, the hydraulic piston corer (HPC) was used to core to 107.9 m, with 89% recovery. Hole 515B was washed to 94.9 m, rotary drilled to 636.4 m, with 79% recovery. The lithologic section is divided into three lithologic units. 351 m of dark greenish gray biosiliceous mud and mudstone of middle Miocene to late Oligocene age with occasional nannoplankton-rich and rare foraminifer-rich horizons. Subunit 2b contains 84 m of dark greenish gray terrigenous mudstone of late Oligocene age, with only traces of siliceous micro fossils and evidence of silica diagenesis. Unit 3 is 20 m (minimum) of lower Eocene greenish gray calcareous zeolitic mudstone.Site 515 was chosen to study the onset and variability of the flow of Antarctic Bottom Water (AABW) through the Vema Channel into the Brazil Basin. The 22 Ma hiatus between Subunits 2b and 3 includes the Eocene/Oligocene boundary, which might correspond with the onset of AABW production. The lithologic boundary between Subunit 2b and Unit 3 corresponds precisely to a sharp and strongly discordant acoustic reflector, which extends throughout the Brazil Basin. The overlying sediments of Units 1 and 2 are fine grained.Early Eocene. Pelagic carbonates accumulated at normal rates of approximately 4 m/Ma during the early Eocene (Cores 515B-56 and 515B-57). Core 515B-56 grades upward from a pelagic carbonate to a dissolution facies consisting of a zeolitic clay with detrital mineral grains. The core contains thin laminations and cross laminations and a weak magnetic grain fabric aligned in a northnortheast direction, all evidence of active bottom currents beginning in the early Eocene.Early Oligocene to middle Miocene. Biosiliceous and terrigenous mudstones accumulated rapidly (approximately 40 m/Ma). Considerable amounts of detrital minerals and intermittent laminated intervals indicate persistent bottom-current activity. The cessation of siliceous sedimentation during the middle Miocene is an oceanwide event in the tropical and temperate Atlantic and reflects a major threshold event of paleocirculation. That event is probably related to the widening of Drake Passage and consequent deepening of the eastward circumpolar flow, which may in turn have shifted the South Atlantic circulation from a pattern of meridional flow to one of zonal flow. The initiation of strong eastward circumpolar flow may have blocked the entry of cold and productive Antarctic and sub-Antarctic waters into the South and central Atlantic, and siliceous sedimentation abruptly ceased in the lower and middle latitudes.Middle Miocene to middle Pleistocene. Terrigenous mudstones and intermittent layers of biogenic carbonate accumulated at rates of about 20 m/Ma. Absence of significant quantities of displaced Antarcti...

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Section: Site 515mentioning

confidence: 99%

Site 515: Brazil Basin

Barker¹,

Carlson²,

Johnson³

1983

Initial Reports of the Deep Sea Drilling Project

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“…Oxygen and carbon isotopic records across the Eocene-Oligocene transition suggest major changes in bottom-water exchange. Eocene bottom-water conditions are generally believed to have been warm, oxygenated, and relatively sluggish (Miller, 1994;Miller and Tucholke, 1983;Moore et al, 1978). Major changes in bottom-water production occurred in the earliest Oligocene, leading to the formation of widespread deep-sea hiatuses (Moore et al, 1978).…”

Section: Late Eocene-early Oligocene Paleoceanographymentioning

confidence: 99%

“…Eocene bottom-water conditions are generally believed to have been warm, oxygenated, and relatively sluggish (Miller, 1994;Miller and Tucholke, 1983;Moore et al, 1978). Major changes in bottom-water production occurred in the earliest Oligocene, leading to the formation of widespread deep-sea hiatuses (Moore et al, 1978). Oxygen isotopes across this transition show significant cooling of bottom waters, and carbon isotopes suggest changing bottom-water sources (Miller, 1994).…”

Section: Late Eocene-early Oligocene Paleoceanographymentioning

confidence: 99%

“…The late Eocene and early Oligocene are notoriously difficult intervals to study because the invigoration of bottom waters led to the development of widespread deep-sea hiatuses (Moore et al, 1978). The Norwegian-Greenland Sea was the conduit for Arctic-produced bottom waters during the "pulse" of Northern Component Water documented by Miller (1994).…”

Section: Late Eocene-early Oligocene Paleoceanographymentioning

confidence: 99%

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Late Paleogene Diatom Biostratigraphy and Paleoenvironments of the Northern Norwegian-Greenland Sea

Scherer¹,

Koç²

1996

Proceedings of the Ocean Drilling Program

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“…The age of the reflector is thought to be latest Eocene in the Rockall Plateau and Rockall Trough (Roberts, 1975) and the Reykjanes Ridge (Ruddiman, 1972), and earliest Oligocene in the Labrador Sea (Miller et al, 1982). Miller et al (1982) note that the timing of increased bottom circulation suggested by reflector R4 provides an explanation for the widespread hiatuses in late Eocene to Oligocene sections, particularly in the North Atlantic (Moore et al, 1978;Keller et al, 1987). Coincident with these hiatuses, Haq et al (1987) show a short-term fall in eustatic sea level in the earliest Oligocene.…”

Section: Eocene-oligocene Paleoceanography Of the Norwegian-greenlandmentioning

confidence: 98%

Paleoceanography and Biostratigraphy of Paleogene Radiolarians from the Norwegian-Greenland Sea

Hull¹

1996

Proceedings of the Ocean Drilling Program

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Eocene and Oligocene radiolarians were recovered from two sites on Ocean Drilling Program (ODP) Leg 151. Early Oligocene to early late Oligocene radiolarians have been extracted from material cored at Site 908 on the Hovgàrd Ridge (Fram Strait). Although rare and only moderately preserved, these assemblages represent the northernmost occurrence of radiolarians recovered by either the Deep Sea Drilling Project or ODP thus far. Site 913 on the East Greenland margin has yielded a sequence of moderately diverse middle Eocene to earliest Oligocene radiolarians. In total, -75 species have been documented herein from both sites.Previous radiolarian biostratigraphies developed for the Norwegian-Greenland Sea were used as an initial basis for Leg 151 age dating. However, complications introduced by Leg 38 spot-coring techniques and radiolarian endemism are highlighted by Site 913 material that does not fit easily into either of the previous biostratigraphic zonations proposed for this region. Consequently, age determinations are based in part on comparison of Site 913 with Leg 38 sites as well as calibration of radiolarian events with other microfossil groups (diatoms, silicoflagellates, and dinoflagellates) present in Hole 913B. The combined stratigraphies suggest the presence of the Eocene/Oligocene boundary in the uppermost part of the biosiliceous sequence at Site 913. The uppermost part of this interval is characterized by the dominance of robust radiolarian groups, broken radiolarian tests, rare diatoms and increased reworking of radiolarians and dinoflagellates. These changes are interpreted as evidence for increased bottomwater circulation associated with radiolarian blooms at or just above the Eocene/Oligocene boundary. These findings concur with previous studies indicating increased bottomwater circulation in the North Atlantic during this same period of geologic time.

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Cenozoic Hiatuses in Pelagic Sediments

Cited by 171 publications

References 6 publications

Site 515: Brazil Basin

Site 515: Brazil Basin

Late Paleogene Diatom Biostratigraphy and Paleoenvironments of the Northern Norwegian-Greenland Sea

Paleoceanography and Biostratigraphy of Paleogene Radiolarians from the Norwegian-Greenland Sea

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