Calcareous nannofloral response to Termination II at 45°N, 25°W (northeast Atlantic)

Lototskaya, Anna; Ziveri, Patrizia; Ganssen, G.M.; Hinte, J.E. van

doi:10.1016/s0377-8398(98)00005-x

Cited by 36 publications

(15 citation statements)

References 50 publications

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“…Vertical grey boxes highlight the interglacial intervals (marine oxygen isotope stages, MIS, are labeled across the bottom), and vertical hatched bars reflect the timing of Heinrich events, which are numbered across the top. The timing of Heinrich events 14 and 15 are estimated from Lototskaya et al [] and Feldmeijer et al [].…”

Section: Resultsmentioning

confidence: 99%

ExploringGloborotalia truncatulinoidescoiling ratios as a proxy for subtropical gyre dynamics in the northwestern Atlantic Ocean during late Pleistocene Ice Ages

Billups

Hudson²,

Kunz

et al. 2016

Paleoceanography

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We explore the use of the coiling direction of planktic foraminifer Globorotalia truncatulinoides in sediment cores from the northwestern subtropical Atlantic Ocean as a proxy for variations in the intensity of the western boundary of the subtropical gyre over the past 280 kyr. Core‐top sediments from the study region are dominated by the left coiling variety consistent with the deep permanent thermocline at the study sites (KNR140‐37PC and Ocean Drilling Program Site 1059). Downcore G. truncatulinoides (sinistral) maxima occur in conjunction with 14 out of the 25 (Northern and Southern Hemisphere) precession maxima contained in the study interval. The agreement between the dominance of left coiling tests and the precession index of the Southern Hemisphere, in particular, supports a link between a deep thermocline in the northwestern subtropical Atlantic and northward flow of equatorially sourced warm surface currents, a situation analogous to the Late Holocene. Interglacial marine oxygen isotope stage (MIS) 5 lacks G. truncatulinoides (s) minima attesting to the relative stability of the western boundary during an interval of prolonged global warmth. G. truncatulinoides (s) disappear during the glacial extremes of MIS 2, 6, and 8 implying a weaker western boundary current at these times. Our results support that the coiling direction of this species is sensitive to variations in hydrography of the western boundary of the subtropical gyre. Because of the association between G. truncatulinoides (s) and precession maxima in both hemispheres, results support the importance of oceanic heat transport in half‐precession climate variability in the North Atlantic.

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Section: Resultsmentioning

confidence: 99%

ExploringGloborotalia truncatulinoidescoiling ratios as a proxy for subtropical gyre dynamics in the northwestern Atlantic Ocean during late Pleistocene Ice Ages

Billups

Hudson²,

Kunz

et al. 2016

Paleoceanography

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“…Two more peaks with a larger total range are observed at ~244 kyr (5.1‰) and ~210 kyr (4.9‰) coinciding with increased numbers of particles in our core consistent with the designation ice‐rafted debris (for timing correlation, see magnetic susceptibility records in Lototskaya et al . [] and Robinson et al . []), indicating a large iceberg discharge during a HE and reflect a similar scenario of freshwater depletion in δ 18 O values brought about by a meltwater pulse.…”

Section: Resultsmentioning

confidence: 99%

“…(a) Planktonic foraminiferal stratigraphy of core T90‐9P from Lototskaya et al . [] based on 30–50 specimens of Globorotalia inflata compared to the planktonic stack of Huybers [] in red and single‐specimen (b) δ 18 O and (c) δ 13 C data for G . truncatulinoides dextral of four size fractions 212–250 µm (black), 250–300 µm (blue), 300–355 µm (red), and 355–400 µm (green).…”

Section: Methodsmentioning

confidence: 99%

Reconstructing the depth of the permanent thermocline through the morphology and geochemistry of the deep dwelling planktonic foraminifer Globorotalia truncatulinoides

Feldmeijer¹,

Metcalfe²,

Brummer

et al. 2015

Paleoceanography

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Geochemical and morphological characteristics of Globorotalia truncatulinoides, a deep dwelling planktonic foraminifer, have been used since the mid-1950s to infer (paleo)oceanographic conditions of the upper ocean. The coiling ratio has been linked to different water masses and stable oxygen isotope signal of this species to changes in depth habitat and/or season. Here we show that the isotopic composition of single specimens covering Termination III of multiple size fractions of North Atlantic G. truncatulinoides sinistral is indicative of a deeper calcification depth in the water column compared to G. truncatulinoides dextral as previously indirectly inferred in a plankton tow study. Furthermore, the change in coiling ratio from dominantly G. truncatulinoides dextral (95%) to brief episodes of dominantly G. truncatulinoides sinistral (80%) gives a strong indication of deepening of the permanent thermocline during periods in which G. truncatulinoides sinistral was dominant. The position of the permanent thermocline during marine isotope stages 8 and 7 echoes the relative strength of the Atlantic meridional overturning circulation (AMOC), dominated by interglacial-glacial dynamics. We demonstrate that Glacial Heinrich (ice-rafted debris) events appear to proceed a permanent thermocline shoaling, whereas interglacial Heinrich events follow the shoaling of the permanent thermocline, likely a result of a weakened AMOC.

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“…The results from DS97‐2P include previously published Holocene coccolith data (Balestra et al , 2010). For coccolith analyses the samples were prepared using a combined dilution/filtering technique (Lototskaya et al , 1998; Ziveri et al , 1999). The analyses were performed using a Zeiss Axioplan microscope at 1560 magnification, in cross‐polarized and phase‐contrasting light.…”

Section: Methodsmentioning

confidence: 99%

Alkenones and coccoliths in ice‐rafted debris during the Last Glacial Maximum in the North Atlantic: implications for the use of U^K₃₇′ as a sea surface temperature proxy

Rosell‐Melé

Balestra

Kornilova

et al. 2011

J Quaternary Science

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The U K 37 0 index has proven to be a robust proxy to estimate past sea surface temperatures (SSTs) over a range of time scales, but like any other proxy, it has uncertainties. For instance, in reconstructions of the Last Glacial Maximum (LGM) in the northern North Atlantic, U K 37 0 indicates higher temperatures than those derived from foraminiferal proxies. Here we evaluate whether such warm glacial estimates are caused by the advection of reworked alkenones in ice-rafted debris (IRD) to deep-sea sediments. We have quantified both coccolith assemblages and alkenones in sediments from glaciogenic debris flows in the continental margins of the northern North Atlantic, and from a deep-sea core from the Reykjanes Ridge. Certain debris flow deposits in the North Atlantic were generated by the presence of massive ice-sheets in the past, and their associated ice streams. Such deposits are composed of the same materials that were present in the IRD at the time they were generated. We conclude that ice rafting from some locations was a transport pathway to the deep sea floor of reworked alkenones and pre-Quaternary coccolith species during glacial stages, but that not all of the IRD contained alkenones, even when reworked coccoliths were present. We speculate that the ratio of reworked coccoliths to alkenone concentration might be useful to infer whether significant reworked alkenone inputs from IRD did occur at a particular site in the glacial North Atlantic. We also observe that alkenones in some of the debris flows contain a colder signal than estimated for LGM sediments in the northern North Atlantic. This is also clear in the deep-sea core studied where the warmest intervals do not correspond to the intervals with large inputs of reworked coccoliths or IRD. We conclude that any possible bias to U K 37 0 estimates associated with reworked alkenones is not necessarily towards higher values, and that the high SST anomalies for the LGM are unlikely to be the result of a bias caused by IRD inputs.

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Calcareous nannofloral response to Termination II at 45°N, 25°W (northeast Atlantic)

Cited by 36 publications

References 50 publications

ExploringGloborotalia truncatulinoidescoiling ratios as a proxy for subtropical gyre dynamics in the northwestern Atlantic Ocean during late Pleistocene Ice Ages

ExploringGloborotalia truncatulinoidescoiling ratios as a proxy for subtropical gyre dynamics in the northwestern Atlantic Ocean during late Pleistocene Ice Ages

Reconstructing the depth of the permanent thermocline through the morphology and geochemistry of the deep dwelling planktonic foraminifer Globorotalia truncatulinoides

Alkenones and coccoliths in ice‐rafted debris during the Last Glacial Maximum in the North Atlantic: implications for the use of U^K₃₇′ as a sea surface temperature proxy

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Calcareous nannofloral response to Termination II at 45°N, 25°W (northeast Atlantic)

Cited by 36 publications

References 50 publications

ExploringGloborotalia truncatulinoidescoiling ratios as a proxy for subtropical gyre dynamics in the northwestern Atlantic Ocean during late Pleistocene Ice Ages

ExploringGloborotalia truncatulinoidescoiling ratios as a proxy for subtropical gyre dynamics in the northwestern Atlantic Ocean during late Pleistocene Ice Ages

Reconstructing the depth of the permanent thermocline through the morphology and geochemistry of the deep dwelling planktonic foraminifer Globorotalia truncatulinoides

Alkenones and coccoliths in ice‐rafted debris during the Last Glacial Maximum in the North Atlantic: implications for the use of UK37′ as a sea surface temperature proxy

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Alkenones and coccoliths in ice‐rafted debris during the Last Glacial Maximum in the North Atlantic: implications for the use of U^K₃₇′ as a sea surface temperature proxy