Response of the Mid‐Cretaceous global oceanic circulation to tectonic and CO<sub>2</sub> forcings

Poulsen, Christopher J.; Barron, Eric J.; Arthur, Michael A.; Peterson, W. H.

doi:10.1029/2000pa000579

Cited by 191 publications

(159 citation statements)

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“…A widespread hiatus near the C/T boundary in the late Cenomanian in the South Atlantic [Zimmerman et al, 1987] and Tethys [de Graciansky et al, 1984] may be due to the initiation of this deep-water connection and erosive currents [Wagner and Pletsch, 2001] between the North and South Atlantic and may record this connection. The models of Poulsen et al [2001Poulsen et al [ , 2003 and Handoh et al [1999] demonstrate that the opening of the North-South Atlantic gateway could have been responsible for reorganization of deep-water circulation patterns resulting in introduction of water from the South Atlantic into the North Atlantic basin. The long-term effect of this event was the ventilation of the Atlantic [Poulsen et al, 2001] by Antarctic Bottom Water but the short-term initiation of a new deep-water source from the South Atlantic could have displaced nutrient-rich water closer to the surface either making it more easily tapped by wind-driven mixing or through increased meridional overturning and higher rates of upwelling.…”

Section: C-t Boundary Eventmentioning

confidence: 99%

“…Circulation modeling in the works of Poulsen et al [2001] and Handoh et al [1999] indicates that persistent wind-driven upwelling was likely at Demerara Rise. Thick sequences of organic-matter-rich deposits in the equatorial Atlantic from the coast of West Africa to Venezuela through the mid-Cretaceous [Bralower and Lorente, 2003;Kuhnt et al, 1997;Schlanger et al, 1987] support these modeling results.…”

Section: Geochemical Patternsmentioning

confidence: 99%

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Nitrogen cycling during the Cretaceous, Cenomanian‐Turonian Oceanic Anoxic Event II

Junium

Arthur

2007

Geochem Geophys Geosyst

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Low δ15N values, ranging from +1.2‰ to −3.9‰, and atomic carbon/nitrogen (C/N) ratios of 25–50 are characteristic of “black shales” deposited during the Cenomanian‐Turonian boundary interval and Oceanic Anoxic Event II (OAE II). An observed antithetic relationship between C/N ratios and δ15N could suggest a predominance of terrestrially derived organic matter or a diagenetic control on δ15N variability shifting bulk δ15N values lower. However, Hydrogen Indices (HI) generally >450, and a positive correlation of HI with C/N mitigates against a significant terrestrial organic matter fraction. High C/N values are likely the result preferential degradation of labile, N‐rich compounds during early diagenesis and loss of N as ammonium from sediments through time. A hypothetical model that considers the degradation of a 15N‐enriched labile protein fraction yields only small, 1–2‰ negative shifts in δ15N. However, 15N depletion during diagenesis is contrary to normal isotope kinetics which should result in 15N enrichment of bulk organic matter. Therefore we conclude that the bulk δ15N values in this study reflect primary changes in the nitrogen cycle. The δ15N data support the hypothesis of expanded nitrogen fixation driven by upwelling of nutrient‐nitrogen poor, phosphorus replete waters during OAE II and from the mid‐Cenomanian to Santonian at Demerara Rise. The low δ15N values, which are significantly lower than bulk δ15N values in modern regions where nitrogen fixation is known to be important, probably result from a more significant fraction of dissolved inorganic nitrogen being produced by nitrogen fixation. During the peak of OAE II a marked shift to lower δ15N values is observed. This shift possibly reflects greater utilization of 15N‐depleted ammonium during a chemocline upward excursion (CUE). Dominance of low δ15N values from other periods of more widespread marine anoxia is likely the result of similar processes.

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Section: C-t Boundary Eventmentioning

confidence: 99%

Section: Geochemical Patternsmentioning

confidence: 99%

Nitrogen cycling during the Cretaceous, Cenomanian‐Turonian Oceanic Anoxic Event II

Junium

Arthur

2007

Geochem Geophys Geosyst

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152

135

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“…This interval is known as a typical greenhouse period caused largely by increased CO 2 from elevated global igneous activity (Jones & Jenkyns 2001;Poulsen et al 2001). It is marked by a major warming peak and globally averaged surface temperatures more than 14 °C higher than those of today (Tarduno et al 1998), ~ 100 -200 m higher sea level than that of today (Haq et al 1987;Miller et al 2005), a lack of permanent ice sheets and oceanic circulations (Frakes et al 1992).…”

Section: Introductionmentioning

confidence: 99%

Planktonic foraminiferal turnover across the Cenomanian – Turonian boundary (OAE2) in the northeast of the Tethys realm, Kopet-Dagh Basin

Kalanat¹,

Vahidinia²,

Vaziri‐Moghaddam³

et al. 2016

Geologica Carpathica

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Two Late Cenomanian -Early Turonian (C-T) intervals of the eastern part of the Kopet-Dagh basin, NE Iran have been investigated to evaluate the response of planktonic foraminifera to the geological event OAE2. The Gharesu and Taherabad sections with the thicknesses of 30 m and 22.5 m are composed of shale and marl interbedded with glauconitic sandstone. Three biozones Rotalipora cushmani, Whiteinella archaeocretacea and Helvetoglobotruncana helvetica were recognized based on study of planktonic foraminifera, in these sections. We observed the patterns of planktonic foraminiferal assemblage changes around the C-T boundary and divided this succession into several successive intervals. This study confirms that OAE2 was a long term event. A gradual perturbation in the study successions starts in the interval 1 with low abundance and diversity of planktonic foraminifera. An enhanced oxygen minimum zone (OMZ) occurs in the interval 3 which coincides with a temporary absence of planktonic foraminifera and sedimentation of framboidal pyrite. High diversity of planktonic foraminifera and appearance of new genera in the interval 5 indicate return of normal conditions to the basin. A significant short-term sea surface temperature cooling is also indicated by planktonic foraminiferal turnover and carbonate contents in the interval 2 which is comparable with other parts of the Tethys Ocean, Boreal sea and Atlantic region.

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“…Estimates of pCO 2 for the mid-Cretaceous range between 2 and 6 times more than the modern level (Cerling 1991). The maximum sea level highstand during that period was ac- companied by enhanced rates of saline deep water formation, higher rates of upwelling, and consequently, increased sea surface fertility and productivity, which led to the deposition of organic carbon-rich facies at the Cenomanian/Turonian boundary (Poulsen et al 2001). The average δ 18 O of the seawater (δ 18 O sw ) of Tethyan Cretaceous ocean is estimated within the range of -1‰ to -0.5‰ VSMOW at 34‰ salinity (Steuber 1999).…”

mentioning

confidence: 99%

Carbon and oxygen stable isotopes of selected Cenomanian and Turonian rudists from Egypt and Czech Republic, and a note on changes in rudist diversity

El-Shazly¹,

Košťák²,

Kloučková³

et al. 2011

Bull. Geosci.

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The stable isotope record and diversity of Cenomanian and Turonian rudists were compared for areas located at low paleolatitudes (10°N -Northern Egypt; 5 samples; 13 analyses) and middle paleolatitudes (35°N -Czech Republic, Bohemian Cretaceous Basin, BCB; 4 samples; 7 analyses). The oxygen isotope data indicate that the δ 18 O value of seawater was not identical for both areas. Moreover, local variations in seawater δ 18 O in the range of at least ±1‰ are probable in the shallow water near-shore environment where the rudists lived. Supposing a value of -1‰ VSMOW for contemporaneous seawater, the paleotemperature can be calculated as being between 24.5 and 31.5°C for the Late Cenomanian and between 32.9 and 34.7°C for the Early Turonian in the BCB. The δ 18 O seawater value for the northern part of Egypt was probably slightly lower. Calculation using a seawater value of -1.5‰ VSMOW gives temperatures for the Egypt in the range of 31.0 to 38.8°C for the Late Cenomanian and 35.5 to 41.2°C for the Turonian. The sclerochronological isotope profiles within one shell show changes of the calcite δ 18 O value, probably reflecting seasonal changes, with the largest observed within-shell temperature shift corresponding to 8°C. The analyzed pilot sample set shows that the BCB and Egyptian rudists contain valuable paleoenvironmental information and that a detailed isotope study is needed. Rudist generic diversity of both areas was also compared. The Cenomanian and Turonian rudist assemblages from Egypt and the BCB show similar generic diversity, and also display a similar marked diversity decrease across the Cenomanian/Turonian boundary interval. It is important to note that both areas have similar diversity on the generic and partially species level during the Cenomanian and Turonian. •

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Response of the Mid‐Cretaceous global oceanic circulation to tectonic and CO₂ forcings

Cited by 191 publications

References 65 publications

Nitrogen cycling during the Cretaceous, Cenomanian‐Turonian Oceanic Anoxic Event II

Nitrogen cycling during the Cretaceous, Cenomanian‐Turonian Oceanic Anoxic Event II

Planktonic foraminiferal turnover across the Cenomanian – Turonian boundary (OAE2) in the northeast of the Tethys realm, Kopet-Dagh Basin

Carbon and oxygen stable isotopes of selected Cenomanian and Turonian rudists from Egypt and Czech Republic, and a note on changes in rudist diversity

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Response of the Mid‐Cretaceous global oceanic circulation to tectonic and CO2 forcings

Cited by 191 publications

References 65 publications

Nitrogen cycling during the Cretaceous, Cenomanian‐Turonian Oceanic Anoxic Event II

Nitrogen cycling during the Cretaceous, Cenomanian‐Turonian Oceanic Anoxic Event II

Planktonic foraminiferal turnover across the Cenomanian – Turonian boundary (OAE2) in the northeast of the Tethys realm, Kopet-Dagh Basin

Carbon and oxygen stable isotopes of selected Cenomanian and Turonian rudists from Egypt and Czech Republic, and a note on changes in rudist diversity

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Response of the Mid‐Cretaceous global oceanic circulation to tectonic and CO₂ forcings