Benthic foraminiferal assemblages as indicators of the paleoceanographic conditions in the eastern Equatorial Pacific

Ovsepyan, E. A.; Иванова, Е. В.

doi:10.1134/s0001437009010147

Cited by 10 publications

(5 citation statements)

References 16 publications

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“…The main positive excursions on this axis, as well as peaks in abundance of oxic species, occur during H events. This pattern is also similar to the serial/spiral benthic foraminiferal test ratio already reported as an indicator of the redox state of the sediments and is influenced by the bottom water ventilation and current velocity [ Nameroff et al ., ; Murray , ; Schumacher et al ., ; Ovsepyan and Ivanova , ]. Spiral (planispiral and trochospiral) forms are usually considered as epibenthic (surface dwellers) while the serial forms are likely to live within the sediments (shallow to deep infaunal) [ Corliss , ].…”

Section: Discussionmentioning

confidence: 99%

Oxygen history off Baja California over the last 80 kyr: A new foraminiferal-based record

2017

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The intensity of the Oxygen minimum zone (OMZ) of the eastern North Pacific (ENP) experienced strong variations during the last glacial, mirroring changes in the balance between export production (O2 consumption) and water mass ventilation (O2 renewal). In this paper we present a new benthic foraminiferal assemblages record from Core MD02‐2508, recovered from the Pacific slope off Baja California, Mexico. The record reflects oxygen conditions at the northern limit of the OMZ during the last 80 kyr. We statistically identified three assemblages, characteristic of dysoxic, suboxic, and oxic conditions, which we used to produce the first semiquantitative reconstruction of [O2] for the northeastern Pacific Ocean. Our results show that the estimated [O2] covaries with δ18O records from the North Greenland Ice Core Project. Oxygen concentrations overall exhibit moderate values (~1 mL.L−1) during stadials, reaching ~ 2 mL.L−1 during stadials corresponding to Heinrich events in the Atlantic Ocean. Conversely, bottom waters at the core location were strongly depleted in oxygen (<0.5 mL.L−1) during interstadials. Benthic foraminiferal abundance increased with higher export production as recorded by geochemical tracers (Cd/Al ratio). This export production signal increases (decreases) with a fall (rise) in [O2] during interstadials (stadials), suggesting a relationship between both parameters during these intervals. The influence of ventilation on oxygenation is also a key player. O2 pulses suggested by the downcore records of serial/spiral test ratio and abundance of oxic species may be explained by enhanced ventilation during Heinrich stadials, in agreement with latest modeling‐based oceanic circulation reconstructions.

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Section: Discussionmentioning

confidence: 99%

Oxygen history off Baja California over the last 80 kyr: A new foraminiferal-based record

2017

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“…ka in Core MD02-2529 (Ovsepyan and Ivanova 2009 , Fig 7.13b). ka in Core MD02-2529 (Ovsepyan and Ivanova 2009 , Fig 7.13b).…”

Section: Pole-to-equator Teleconnections In the Eastern Equatorial Pamentioning

confidence: 96%

The Global Thermohaline Paleocirculation

Иванова¹

2009

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“…The ENP core tops (see Table 1) were carried out at CEREGE (preparation, census counting of benthic foraminifera, and morphometric measurements), except for cores MD02-2503 and MD02-2504 (Ohkushi et al, 2013) and Core MD02-2529 (Ovsepyan and Ivanova, 2009). The ESP Peruvian-margin OMZ core tops (ST1 to ST13) were recovered during the April 2015 CRIO campaign on the R/V Olaya where sediment sampling and CTDO measurements were carried out on five sites along the Callao transect (ST1 to ST5) and two sites along the Pisco transect (ST12 to ST13), and these were also prepared and processed at CEREGE.…”

Section: Core Materialsmentioning

confidence: 99%

Toward a global calibration for quantifying past oxygenation in oxygen minimum zones using benthic Foraminifera

et al. 2021

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Abstract. Oxygen minimum zones (OMZs) are oceanic areas largely depleted in dissolved oxygen, nowadays considered in expansion in the face of global warming. To investigate the relationship between OMZ expansion and global climate changes during the late Quaternary, quantitative oxygen reconstructions are needed but are still in their early development. Here, past bottom water oxygenation (BWO) was quantitatively assessed through a new, fast, semi-automated, and taxon-independent morphometric analysis of benthic foraminiferal tests, developed and calibrated using WNP (western North Pacific, including its marginal seas), ENP (eastern North Pacific), and ESP (eastern South Pacific) OMZ samples. This new approach is based on an average size and shape index for each sample. This method, as well as two already published micropalaeontological techniques based on benthic foraminiferal assemblages' variability and porosity investigation of a single species, was calibrated here based on availability of new data from 45 core tops recovered along an oxygen gradient (from 0.03 to 2.88 mL L−1) from the WNP, ENP, EEP (eastern Equatorial Pacific), ESP, SWACM (southwest African continental margin), and AS (Arabian Sea) OMZs. Global calibrated transfer functions are herein proposed for these methods. These micropalaeontological reconstruction approaches were then applied to a palaeorecord from the ENP OMZ to examine the consistency and limits of these methods, as well as the relative influence of bottom and pore waters on these micropalaeontological tools. Both the assemblage and morphometric approaches (which are also ultimately based on the ecological response of the complete assemblage and faunal succession according to BWO) gave similar and consistent past BWO reconstructions, while the porosity approach (based on a single species and its unique response to a mixed signal of bottom and pore waters) showed ambiguous estimations.

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Benthic foraminiferal assemblages as indicators of the paleoceanographic conditions in the eastern Equatorial Pacific

Cited by 10 publications

References 16 publications

Oxygen history off Baja California over the last 80 kyr: A new foraminiferal-based record

Oxygen history off Baja California over the last 80 kyr: A new foraminiferal-based record

The Global Thermohaline Paleocirculation

Toward a global calibration for quantifying past oxygenation in oxygen minimum zones using benthic Foraminifera

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