The Foraminiferal Isotope Record across the Eocene/Oligocene Boundary at Deep Sea Drilling Project Site 540

Bélanger, Paul; Matthews, R. K.

doi:10.2973/dsdp.proc.77.124.1984

Cited by 6 publications

(3 citation statements)

References 15 publications

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“…T‐ΔT plots with planktonic foraminiferal SST estimates from the Gulf Coastal region [ Boersma et al , 1987; Wade et al , 2000; Belanger and Matthews , 1984] (temperature calibration follows Kobashi et al [2001], which is comparable with this study's temperatures) clearly show cooler isotopic temperatures for planktonic foraminifera (Figure 12). For the early Eocene, planktonic foraminiferal SST estimate is 23°C and TBST is 26°C, suggesting the majority of planktonic foraminiferal test precipitation probably occurred below the seasonal thermocline.…”

Section: Water Mass Stability and Temperature Reconstructions From Grsupporting

confidence: 84%

Water mass stability reconstructions from greenhouse (Eocene) to icehouse (Oligocene) for the northern Gulf Coast continental shelf (USA)

Kobashi¹,

Grossman

Dockery

et al. 2004

Paleoceanography

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[1] Shallow water mass characteristics such as temperature and density profile play a critical role in the climate system. We have developed a new method by which to reconstruct the ancient shallow water mass stability on the continental shelf using oxygen isotope variation within mollusc shells and fish otoliths and applied the method to an important interval in Earth history, the most recent transition from Greenhouse (Eocene) to Icehouse (Oligocene) climate modes. We define the slope of summer temperature (density) versus the seasonal range in temperature (density) as an indicator of water mass stability. In addition, extrapolation of the regression to zero seasonality is a proxy for temperature at the bottom of the seasonal thermocline (TBST). During the greenhouse world (the early Eocene and middle Eocene) the water mass plot shows an unstable water mass, agreeing with previous planktonic foraminiferal studies showing that temperature gradients at this time were much smaller than at present. During the middle to late Eocene transition, a substantial increase in water mass stability occurred. Significant cooling ($5°C) of the TBST at this transition indicates that the greater cooling of deeper water relative to surface water caused the increase in water mass stability. The changes in water column structure at this transition were the most likely cause of a major extinction of planktonic foraminifera from warm to cold water taxa. The late Eocene T-DT profile is very similar to modern profiles, suggesting that shallow water mass structure became similar to that of the modern Gulf Coastal shelf by the late Eocene. At the Eocene/ Oligocene (E/O) boundary, no major change in water mass structure is identified. This agrees with the observation that no major extinction of planktonic foraminifera is found at the E/O boundary.

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Section: Water Mass Stability and Temperature Reconstructions From Grsupporting

confidence: 84%

Water mass stability reconstructions from greenhouse (Eocene) to icehouse (Oligocene) for the northern Gulf Coast continental shelf (USA)

Kobashi¹,

Grossman

Dockery

et al. 2004

Paleoceanography

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“…Cleaning method (oxidative or reductive) TEX 86 Schouten et al 740 Kim et al 704 O'Brien et al 696 Tierney and Tingley, 2014 31 U K 37 ′ Müller et al 741 Conte et al 742 Tierney and Tingley, 2018 33 Table 6. Non-exhaustive list of non-thermal predictor variables associated with each proxy system in PhanSST, and some commonly-used calibrations.…”

Section: Salinitymentioning

confidence: 99%

The PhanSST global database of Phanerozoic sea surface temperature proxy data

et al. 2022

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Paleotemperature proxy data form the cornerstone of paleoclimate research and are integral to understanding the evolution of the Earth system across the Phanerozoic Eon. Here, we present PhanSST, a database containing over 150,000 data points from five proxy systems that can be used to estimate past sea surface temperature. The geochemical data have a near-global spatial distribution and temporally span most of the Phanerozoic. Each proxy value is associated with consistent and queryable metadata fields, including information about the location, age, and taxonomy of the organism from which the data derive. To promote transparency and reproducibility, we include all available published data, regardless of interpreted preservation state or vital effects. However, we also provide expert-assigned diagenetic assessments, ecological and environmental flags, and other proxy-specific fields, which facilitate informed and responsible reuse of the database. The data are quality control checked and the foraminiferal taxonomy has been updated. PhanSST will serve as a valuable resource to the paleoclimate community and has myriad applications, including evolutionary, geochemical, diagenetic, and proxy calibration studies.

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“…SSQ section is represented in a chronological scale and the other sections are in core depth (CD; Site 540) and section thickness (ST; BC section) metric scales. Redrawn fromBelanger & Matthews (1984),Saunders et al (1984) andKatz et al (2008).…”

mentioning

confidence: 99%

Eocene/Oligocene global disruption and the revolution of Caribbean mangroves

Rull¹

2022

Preprint

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In a recent paper, the author demonstrated that, in contrast with the prevailing view of eventual gradual regional differentiation from a hypothetical Cretaceous pantropical mangrove belt around the Tethys Sea, the Caribbean mangroves originated de novo in the Eocene after the evolutionary appearance of the first mangrove-forming tree species known for the region, the ancestor of the extant Pelliciera. This paper represents a second step in the analysis of the evolution of Caribbean mangroves dealing with the most important change experienced by these communities, occurring across the Eocene‒Oligocene transition (EOT), which is termed here the Caribbean mangrove revolution. This shift consisted of the disappearance of the primeval Pelliciera mangroves and their replacement by mangrove communities dominated by Rhizophora, a newly emerged mangrove tree that still dominates extant Caribbean mangroves. This paper first reviews the available literature on the EOT global disruption (tectonic and paleogeographic reorganizations, ocean circulation, cooling, Antarctic glaciation, sea-level fall) and its regional manifestations in the study area, along with the corresponding biotic responses. This provides the paleoenvironmental framework with which to analyze the EOT mangrove revolution using the nearly 80 pollen records available for the region. In the circum-Caribbean region, cooling of 3-6 °C and a sea-level fall of 67 m were recorded between 33.8 and 33.5 Ma, which led to significant shifts in dispersal pathways and barriers, as well as in marine paleocurrents. Late Eocene mangroves were dominated by the autochthonous Pelliciera (up to 60% of pollen assemblages), while Rhizophora, which likely arrived from the Indo-Pacific region by long-distance dispersal, was absent or very scarce. After the EOT, the situation was radically different, as the mangroves were widely dominated by Rhizophora, and Pelliciera, when present, was a subordinate mangrove element (<10%). At the same time, Pelliciera, which had been restricted to a small patch (Central America and NW South America or CA/NWSA) during the Eocene, expanded its range across the Caribbean and beyond, always as a minor component of Rhizophora mangroves. The dominance shift could have been due to the cooling, by favoring the expansion of the euryclimatic and vagile Rhizophora over the stenoclimatic Pelliciera, of limited dispersal ability. This is considered a case of competitor coexistence by niche segregation. In addition, Rhizophora could have facilitated the expansion of Pelliciera by providing refuge against environmental and biotic stressors, notably light intensity and salinity. The Eocene Pelliciera mangroves never returned, but this species survived to the present as a minor element and experienced significant range shifts along three main phases, namely, EOT–Miocene expansion to the whole neotropics, Mio-Pliocene contraction to the southern Caribbean margin and Pliocene to recent reorganization to the original Eocene CA/NWSA location. The potential role of Neogene and Pleistocene climatic shifts and human activities in these biogeographical loops (taxon cycles) is discussed, with an emphasis on precipitation. The paper ends by suggesting some prospects for future research.

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The Foraminiferal Isotope Record across the Eocene/Oligocene Boundary at Deep Sea Drilling Project Site 540

Cited by 6 publications

References 15 publications

Water mass stability reconstructions from greenhouse (Eocene) to icehouse (Oligocene) for the northern Gulf Coast continental shelf (USA)

Water mass stability reconstructions from greenhouse (Eocene) to icehouse (Oligocene) for the northern Gulf Coast continental shelf (USA)

The PhanSST global database of Phanerozoic sea surface temperature proxy data

Eocene/Oligocene global disruption and the revolution of Caribbean mangroves

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