Continental margin molybdenum isotope signatures from the early Eocene

Dickson, Alexander J.; Cohen, A. S.; Coe, Angela L.

doi:10.1016/j.epsl.2014.08.004

Cited by 29 publications

(22 citation statements)

References 50 publications

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“…The Mo isotope compositions of these samples were dominated by the residual Mo in the detrital siliciclastic component and thus could not provide information on the palaeoredox conditions in seawater. In contrast, the δ 98 Mo values of the samples from the unweathered zone increased to ~1.15‰, which were characteristic of the suboxic (to anoxic) conditions of continental margin settings (Dickson et al, 2014).…”

Section: Accepted Manuscriptmentioning

confidence: 88%

Influence of palaeoweathering on trace metal concentrations and environmental proxies in black shales

Marynowski

Pisarzowska

Derkowski

et al. 2017

Palaeogeography, Palaeoclimatology, Palaeoecology

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Section: Accepted Manuscriptmentioning

confidence: 88%

Influence of palaeoweathering on trace metal concentrations and environmental proxies in black shales

Marynowski

Pisarzowska

Derkowski

et al. 2017

Palaeogeography, Palaeoclimatology, Palaeoecology

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“…There is considerable evidence for widespread seafloor anoxia in the Tethys during the PETM (see Carmichael et al, , for a recent compilation; Table ). Along the northern margins of the Tethys Sea, there is also evidence for persistent photic zone euxinia (e.g., Dickson et al, ) and intermittent euxinia along the southern and eastern margins during the PETM (Carmichael et al, ). The highly reduced state of the Tethys Sea during the PETM is captured by our model that also indicates the presence of strong photic zone euxinia in the Eastern Tethys (Figure ).…”

Section: Discussionmentioning

confidence: 99%

“…The warming of the ocean, increased nutrient runoff, enhanced stratification, and the oxidation of a large body of reduced carbon are all suggested to have reduced oxygen levels in the oceans during the PETM (Chang et al, ; Dickson et al, ; Nicolo et al, ; Pälike et al, ). Deoxygenated bottom waters are thought to have been commonplace in marginal settings (e.g., Dickson et al, ), and oxygen minimum zones have been suggested to have expanded (Chun et al, ; Pälike et al, ; Zhou et al, ). The presence of geochemical indicators for deoxygenation in the Atlantic, an absence of these in the Pacific Ocean, and the difference in change in the CCD strongly suggest that the carbon source was situated in the Atlantic Ocean (Chun et al, ; Pälike et al, ; Zhou et al, ).…”

Section: Introductionmentioning

confidence: 99%

Investigating Ocean Deoxygenation During the PETM Through the Cr Isotopic Signature of Foraminifera

Remmelzwaal

Dixon

Parkinson

et al. 2019

Paleoceanog and Paleoclimatol

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Over the past several decades, oxygen minimum zones have rapidly expanded due to rising temperatures raising concerns about the impacts of future climate change. One way to better understand the drivers behind this expansion is to evaluate the links between climate and seawater deoxygenation in the past especially in times of geologically abrupt climate change such as the Palaeocene-Eocene Thermal Maximum (PETM), a well-characterized period of rapid warming~56 Ma. We have developed and applied the novel redox proxies of foraminiferal Cr isotopes (δ 53 Cr) and Ce anomalies (Ce/Ce*) to assess changes in paleoredox conditions arising from changes in oxygen availability. Both δ 53 Cr and Cr concentrations decrease notably over the PETM at intermediate to upper abyssal water depths, indicative of widespread reductions in dissolved oxygen concentrations. An apparent correlation between the sizes of δ 53 Cr and benthic δ 18 O excursions during the PETM suggests temperature is one of the main controlling factors of deoxygenation in the open ocean. Ocean Drilling Program Sites 1210 in the Pacific and 1263 in the Southeast Atlantic suggest that deoxygenation is associated with warming and circulation changes, as supported by Ce/Ce* data. Our geochemical data are supported by simulations from an intermediate complexity climate model (cGENIE), which show that during the PETM anoxia was mostly restricted to the Tethys Sea, while hypoxia was more widespread as a result of increasing atmospheric CO 2 (from 1 to 6 times preindustrial values).

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“…The PETM does not feature expansive deposition of organic matter-rich black shales nor is there evidence for severe deoxygenation in open marine settings in a manner that is directly analogous to the Mesozoic OAEs. Whilst there is substantial evidence that O 2 content decreased in the open ocean during the PETM 17 – 19 , severe O 2 reductions were focused within the Arctic and Tethyan realms 20 – 24 but have been noted in other locations 25 . New geochemical proxies that are sensitive to differing changes in redox state paint a more nuanced picture of the degree of deoxygenation during the PETM.…”

Section: Discussionmentioning

confidence: 99%

Perturbation to the nitrogen cycle during rapid Early Eocene global warming

2018

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The degree to which ocean deoxygenation will alter the function of marine communities remains unclear but may be best constrained by detailed study of intervals of rapid warming in the geologic past. The Paleocene–Eocene Thermal Maximum (PETM) was an interval of rapid warming that was the result of increasing contents of greenhouse gases in the atmosphere that had wide ranging effects on ecosystems globally. Here, we present stable nitrogen isotope data from the Eastern Peri-Tethys Ocean that record a significant transition in the nitrogen cycle. At the initiation of the PETM, the nitrogen isotopic composition of sediments decreased by ~6‰ to as low as −3.4‰, signaling reorganization of the marine nitrogen cycle. Warming, changes in ocean circulation, and deoxygenation caused a transition to nitrogen cycle to conditions that were most similar to those experienced during Oceanic Anoxic Events of the Mesozoic.

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Continental margin molybdenum isotope signatures from the early Eocene

Cited by 29 publications

References 50 publications

Influence of palaeoweathering on trace metal concentrations and environmental proxies in black shales

Influence of palaeoweathering on trace metal concentrations and environmental proxies in black shales

Investigating Ocean Deoxygenation During the PETM Through the Cr Isotopic Signature of Foraminifera

Perturbation to the nitrogen cycle during rapid Early Eocene global warming

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