Paleogene Benthic Foraminifers from the Southern Indian Ocean (Kerguelen Plateau): Biostratigraphy and Paleoecology

Mackensen, A.; Berggren, W.A.

doi:10.2973/odp.proc.sr.120.168.1992

Cited by 20 publications

(7 citation statements)

References 24 publications

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“…Additionally, the shallower depth of the Kerguelen Plateau in our Miocene bathymetry steers the sub‐Antarctic front poleward, (Figure 2). The depth of the Kerguelen Plateau in our Miocene bathymetry is ∼1,000 m, consistent with paleodepth constraints from benthic foraminifera [ Mackensen and Berggren , 1992]. To our knowledge the effect of Large Igneous Provinces on poleward heat transport has not been examined and should be the focus of future studies.…”

Section: Discussionsupporting

confidence: 77%

Modeling the Miocene climatic optimum: Ocean circulation

Herold¹,

Huber²,

Müller³

et al. 2012

Paleoceanography

105

113

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Ocean circulation is investigated using the Community Climate System Model 3 (CCSM3) forced with early to middle Miocene (∼20–14 Ma) topography, bathymetry, vegetation and modern CO2. Significant bottom water formation is modeled in the Weddell Sea along with intermediate North Component Water formation in the North Atlantic. This is attributed primarily to stronger‐ and weaker‐than‐modern convective preconditioning in the Weddell and Labrador Seas, respectively. Global meridional overturning and gyre circulation is weaker in the Miocene due to weaker midlatitude westerlies in the southern hemisphere, caused by lowering of the meridional surface temperature gradient, in addition to regional influences on convection. Subsurface temperatures in the Miocene are significantly higher in the far North Atlantic, Greenland‐Norwegian Seas and Arctic basin compared to the present. Ocean heat transport is symmetrical about the equator and resembles that simulated for late Cretaceous and early Cenozoic climates, suggesting the northern hemisphere dominated ocean heat transport active today developed after the middle Miocene. Simulated deep water warming in the Miocene is more than an order of magnitude lower than indicated by proxies. This discrepancy is not reconciled by higher CO2 due to the persistence of sea‐ice at sites of deep water formation. This suggests that either the CCSM3 is insufficiently sensitive to Miocene boundary conditions, greater greenhouse forcing existed than is currently reconstructed, or that proxy records of warming are exaggerated. Given the diversity of global Miocene proxy records and their near‐unanimous estimate of a significantly warmer Earth, the first two options are more likely.

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Section: Discussionsupporting

confidence: 77%

Modeling the Miocene climatic optimum: Ocean circulation

Herold¹,

Huber²,

Müller³

et al. 2012

Paleoceanography

105

113

View full text Add to dashboard Cite

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“…The preferred species was C. praemundulus , but a degree of variability outside the strict definition of the species was allowed. Other Cibicidoides taxa that are less common in Site 738 and 748 sediments, such as C. bradyi , C. eocaenus , C. laurisae , C. micrus , and C. subspiratus [see Mackensen and Berggren , 1992], were avoided and not used for stable isotope analysis in this study. Identification of these taxa was aided by the descriptions and illustrations given by van Morkhoven et al [1986].…”

Section: Methodsmentioning

confidence: 99%

Coupled greenhouse warming and deep‐sea acidification in the middle Eocene

et al. 2009

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[1] The Middle Eocene Climatic Optimum (MECO) is an enigmatic warming event that represents an abrupt reversal in long-term cooling through the Eocene. In order to further assess the timing and nature of this event, we have assembled stable isotope and calcium carbonate concentration records from multiple Deep Sea Drilling Project and Ocean Drilling Program sites for the time interval between $43 and 38 Ma. Revised stratigraphy at several sites and compilation of d O excursion at sites in different geographic regions indicates that the climatic effects of this event were globally extensive. The total duration of the MECO event is estimated at $500 ka, with peak warming lasting <100 ka. Assuming minimal glaciation in the late middle Eocene, $4°-6°C total warming of both surface and deep waters is estimated during the MECO at the study sites. The interval of peak warming at $40.0 Ma also coincided with a worldwide decline in carbonate accumulation at sites below 3000 m depth, reflecting a temporary shoaling of the calcite compensation depth. The synchroneity of deepwater acidification and globally extensive warming makes a persuasive argument that the MECO event was linked to a transient increase in atmospheric pCO 2 . The results of this study confirm previous reports of significant climatic instability during the middle Eocene. Furthermore, the direct link between warming and changes in the carbonate chemistry of the deep ocean provides strong evidence that changes in greenhouse gas concentrations exerted a primary control on short-term climate variability during this critical period of Eocene climate evolution.

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“…Such a verification was carried out here using Deep Sea Drilling Project and Ocean Drilling Project records. Based on these records the depth of the Madagascar Ridge (Schlich, 1974), Mascarene Ridge (Backman et al, 1988;Fisher et al, 1974;, Shatsky Rise, Ontong Java Plateau (Barrera et al, 1993), Kerguelen Plateau (Mackensen and Berggren, 1992), Walvis Ridge (Zachos et al, 2005;Fuetterer, 1984) and the Rio Grande Rise (Perch-Nielsen et al, 1977) were adjusted.…”

Section: Bathymetric Revisionsmentioning

confidence: 99%

A suite of early Eocene (~ 55 Ma) climate model boundary conditions

et al. 2014

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Abstract. We describe a set of early Eocene (~ 55 Ma) climate model boundary conditions constructed in a self-consistent reference frame and incorporating recent data and methodologies. Given the growing need for uniform experimental design within the Eocene climate modelling community and the challenges faced in simulating the prominent features of Eocene climate, we make publicly available our data sets of Eocene topography, bathymetry, tidal dissipation, vegetation, aerosol distributions and river runoff. Major improvements in our boundary conditions over previous efforts include the implementation of the ANTscape palaeotopography of Antarctica, more accurate representations of the Drake Passage and Tasman Gateway, as well as an approximation of sub grid cell topographic variability. Our boundary conditions also include for the first time modelled estimates of Eocene aerosol distributions and tidal dissipation, both consistent with our palaeotopography and palaeobathymetry. The resolution of our data sets is unprecedented and will facilitate high resolution climate simulations. In light of the inherent uncertainties involved in reconstructing global boundary conditions for past time periods these data sets should be considered as one interpretation of the available data and users are encouraged to modify them according to their needs and interpretations. This paper marks the beginning of a process for reconstructing a set of accurate, open-access Eocene boundary conditions for use in climate models.

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Paleogene Benthic Foraminifers from the Southern Indian Ocean (Kerguelen Plateau): Biostratigraphy and Paleoecology

Cited by 20 publications

References 24 publications

Modeling the Miocene climatic optimum: Ocean circulation

Modeling the Miocene climatic optimum: Ocean circulation

Coupled greenhouse warming and deep‐sea acidification in the middle Eocene

A suite of early Eocene (~ 55 Ma) climate model boundary conditions

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