Dysoxic/anoxic episodes in the Aptian-Albian (Early Cretaceous)

Bralower, Timothy J.; Sliter, William V.; Arthur, Michael A.; Leckie, R. Mark; Allard, David; Schlanger, Seymour O.

doi:10.1029/gm077p0005

Cited by 99 publications

(96 citation statements)

References 83 publications

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“…This rationale has been used in the Cretaceous (e.g., Bralower et al, 1993). Several of the zonal units in the OB 80 scheme have already been divided into such units.…”

Section: Application Of Secondary Calcareous Nannofossil Biohorizonsmentioning

confidence: 99%

“…Even though the original zonations of both planktonic foraminifers (e.g., Blow, 1969) and calcareous nannofossils (Martini, 1971;Bukry, 1973Bukry, , 1975aBukry, , 1975bOkada and Bukry, 1980) have proven to be widely applicable, the detailed stratigraphy of nonmarker species can be improved. Resolution of Paleogene biostratigraphies of both groups, therefore, lags significantly behind that of the Neogene and, in the case of the calcareous nannofossils, even that of parts of the Cretaceous (Moore and Romine, 1981;Bralower et al, 1993). The Paleogene is an interval of high species diversity nonetheless (Haq, 1973), and the potential for increased biostratigraphic resolution is good.…”

Section: Introductionmentioning

confidence: 99%

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Calcareous Nannofossil Biostratigraphy of Site 865, Allison Guyot, Central Pacific Ocean: A Tropical Paleogene Reference Section

Bralower¹,

Mutterlose²

1995

Proceedings of the Ocean Drilling Program, 143 Scientific Results

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A relatively expanded and largely complete upper Paleocene to lower Oligocene sequence was recovered from the pelagic cap overlying Allison Guyot, Mid-Pacific Mountains. The sequence consists of calcareous ooze with a high planktonic foraminifer content. Two separate holes (865B and 865C) were drilled with the advanced piston coring system. Samples from these holes have been the target of intensive calcareous nannofossil biostratigraphic investigations. Calcareous nannofossils are moderately well preserved and diverse throughout the sequence recovered, which extends from nannofossil Zone CP3 to CPI 6. Our data show that unconformities occur in the uppermost lower Eocene and at the Eocene/Oligocene boundary, correlating to part of Zones CPU and CP 12 and Zones CP 15 and CP 16, respectively. Most traditional zonal markers are present; however, the rarity of several of them, particularly discoasters, and the overgrowth of others, including species of Tribrachiatus, in the uppermost Paleocene and lower Eocene makes zonal subdivision of part of this sequence difficult. For this reason, more attention has been paid to establishing the precise ranges of nonzonal taxa. We were able to determine 142 zonal and nonzonal events in the Paleogene section by intensively sampling both holes (1-5 samples in each core section). Sample density increased toward the Paleocene/Eocene boundary. Although the events are spread fairly evenly throughout the section, some of the most dramatic turnover occurs in the boundary and early Eocene interval. Currently unobserved gradational forms in nannofossil lineages indicate that parts of this sequence are more expanded than any other yet recovered. Plate reconstructions show that Site 865 was close to the equator at the time Paleogene sediments were deposited. The near completeness, expansion, paleolocation, and shallow burial depth of this sequence render it an ideal low-latitude Paleogene reference section.

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“…This rationale has been used in the Cretaceous (e.g., Bralower et al, 1993). Several of the zonal units in the OB 80 scheme have already been divided into such units.…”

Section: Application Of Secondary Calcareous Nannofossil Biohorizonsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Calcareous Nannofossil Biostratigraphy of Site 865, Allison Guyot, Central Pacific Ocean: A Tropical Paleogene Reference Section

Bralower¹,

Mutterlose²

1995

Proceedings of the Ocean Drilling Program, 143 Scientific Results

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“…Initially described from southeastern France (Vocontian Trough), with coeval correlatives recognized in southern Germany and Austria, its sedimentary record has now been traced through much of the Tethyan-Atlantic region, including deep-sea drilling sites (Bréhéret 1997;Bralower et al . 1993;Leckie et al .…”

Section: The Early Albian (Cretaceous) Paquier Eventmentioning

confidence: 99%

Evidence for rapid climate change in the Mesozoic–Palaeogene greenhouse world

Jenkyns

2003

Philosophical Transactions of the Royal Society of London. Seri

449

308

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The best-documented example of rapid climate change that characterized the socalled 'greenhouse world' took place at the time of the Palaeocene-Eocene boundary: introduction of isotopically light carbon into the ocean-atmosphere system, accompanied by global warming of 5-8• C across a range of latitudes, took place over a few thousand years. Dissociation, release and oxidation of gas hydrates from continental-margin sites and the consequent rapid global warming from the input of greenhouses gases are generally credited with causing the abrupt negative excursions in carbon-and oxygen-isotope ratios. The isotopic anomalies, as recorded in foraminifera, propagated downwards from the shallowest levels of the ocean, implying that considerable quantities of methane survived upward transit through the water column to oxidize in the atmosphere. In the Mesozoic Era, a number of similar events have been recognized, of which those at the Triassic-Jurassic boundary, in the early Toarcian (Jurassic) and in the early Aptian (Cretaceous) currently carry the best documentation for dramatic rises in temperature. In these three examples, and in other less well-documented cases, the lack of a definitive time-scale for the intervals in question hinders calculation of the rate of environmental change. However, comparison with the Palaeocene-Eocene thermal maximum (PETM) suggests that these older examples could have been similarly rapid. In both the early Toarcian and early Aptian cases, the negative carbon-isotope excursion precedes global excess carbon burial across a range of marine environments, a phenomenon that defines these intervals as oceanic anoxic events (OAEs). Osmium-isotope ratios ( 187 Os/ 188 Os) for both the early Toarcian OAE and the PETM show an excursion to more radiogenic values, demonstrating an increase in weathering and erosion of continental crust consonant with elevated temperatures. The more highly buffered strontium-isotope system ( 87 Sr/ 86 Sr) also shows relatively more radiogenic signatures during the early Toarcian OAE, but the early Aptian and Cenomanian-Turonian OAEs show the reverse effect, implying that increased rates of sea-floor spreading and hydrothermal activity dominated over continental weathering in governing sea-water chemistry. The Cretaceous climatic optimum (late Cenomanian to mid Turonian) also shows evidence for abrupt cooling episodes characterized by episodic invasion of boreal faunas into temperate and subtropical regions and changes in terrestrial vegetation; drawdown of CO 2 related to massive marine carbon burial (OAE) may be implicated here. The absence of a pronounced negative carbon-isotope excursion preceding the One contribution of 14 to a Discussion Meeting 'Abrupt climate change: evidence, mechanisms and implications'.

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“…Cretaceous examples include the Toolebuc Formation from the Eromanga Basin, Queensland, Australia, of early late Albian age [Bralower et al, 1993], whose d…”

Section: Mesozoic Versus Quaternary Nitrogen Isotope Ratiosmentioning

confidence: 99%

Nitrogen isotope evidence for water mass denitrification during the Early Toarcian (Jurassic) oceanic anoxic event

Jenkyns¹,

Gröcke²,

Hesselbo³

2001

Paleoceanography

232

151

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Citation for published item:tenkynsD rF gF nd qr¤ okeD hF F nd resseloD F F @PHHIA 9xitrogen isotope evidene for wter mss denitri(tion during the erly orin @turssiA oeni noxi eventF9D leoenogrphyFD IT @TAF ppF SWQETHQF Further information on publisher's website: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. 15 N tot excursion through the exaratum Subzone of the falciferum Zone (defined by characteristic ammonites in the British Isles) broadly correlates with a relative maximum in weight percent total organic carbon and, in some sections, with a negative d 13 C org excursion. Upwelling of a deoxygenated water mass that had undergone partial denitrification is the likely explanation for relative enrichment of d 15 N tot , and parallels may be drawn with Quaternary sediments of the Arabian Sea, Gulf of California, and northwest Mexican margin. The development of Early Toarcian suboxic water masses and consequent partial denitrification is attributed to increases in organic productivity. Approximately coincident phenomena include the following: a relative climatic optimum, realignment of major oceanic current systems, and a possible release of methane gas hydrates from continental margin sediments early in the history of the oceanic anoxic event.

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Dysoxic/anoxic episodes in the Aptian-Albian (Early Cretaceous)

Cited by 99 publications

References 83 publications

Calcareous Nannofossil Biostratigraphy of Site 865, Allison Guyot, Central Pacific Ocean: A Tropical Paleogene Reference Section

Calcareous Nannofossil Biostratigraphy of Site 865, Allison Guyot, Central Pacific Ocean: A Tropical Paleogene Reference Section

Evidence for rapid climate change in the Mesozoic–Palaeogene greenhouse world

Nitrogen isotope evidence for water mass denitrification during the Early Toarcian (Jurassic) oceanic anoxic event

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