Abrupt climatic changes induced by ice-rafting events in the eastern North Atlantic during the late Quaternary: stable isotope and X-ray mineralogical analyses

1998 ◽  
Vol 2 (2) ◽  
pp. 59-67 ◽  
Author(s):  
Myong-Ho Park
Keyword(s):  
Stable Isotope ◽  
North Atlantic ◽  
Late Quaternary ◽  
Climatic Changes ◽  
X Ray ◽  
Ice Rafting ◽  
Eastern North Atlantic

scholarly journals Late Quaternary deep-sea ostracod taxonomy of the eastern North Atlantic Ocean

2015 ◽  
Vol 34 (1) ◽  
pp. 21-49 ◽  
Author(s):  
Moriaki Yasuhara ◽  
Hisayo Okahashi
Keyword(s):  
North Atlantic ◽  
Deep Sea ◽  
North Atlantic Ocean ◽  
Late Quaternary ◽  
Taxonomic Revision ◽  
Quaternary Sediments ◽  
Ocean Drilling Program ◽  
Ocean Drilling ◽  
Eastern North Atlantic ◽  
Microscopy Images

Abstract. Taxonomic revision and re-evaluation of the eastern North Atlantic deep-sea ostracods are conducted based on late Quaternary sediments from Ocean Drilling Program (ODP) Hole 982A, Rockall Plateau, eastern North Atlantic. Twenty-one genera and 51 species were examined and (re-)illustrated with high-resolution scanning electron microscopy images. Six new species are described: Polycope lunaris, Argilloecia labri, Bythoceratina nuda, Cytheropteron colesoabyssorum, Cytheropteron colesopunctatum and Cytheropteron paramediotumidum. Excellent fossil ostracod preservation in this sediment core enabled us to provide a robust taxonomic baseline of the eastern North Atlantic deep-sea ostracods for application to palaeoceanographical, palaeoecological and biogeographical studies.

scholarly journals Quaternary palaeoceanography and palaeogeography in northern Denmark: a review of results from the Skagen cores

1996 ◽  
Vol 43 ◽  
pp. 22-31
Author(s):  
Karen Luise Knudsen ◽  
Keld Conradsen ◽  
, Susanne Heier Nielsen ◽  
Marit-Solveig Seidenkrantz
Keyword(s):  
North Atlantic ◽  
Late Quaternary ◽  
Climatic Changes ◽  
Last Interglacial ◽  
North Atlantic Region ◽  
Atlantic Region ◽  
Radiocarbon Dates ◽  
Marine Deposits ◽  
The North ◽  
Late Weichselian

Palaeoenvironmental reconstructions from the Skagen record contribute to the understanding of Late Quatemary climatic changes and variations in the oceanographic circulation pattem in the entire North Atlantic region. The Skagen cores penetrated c. 192 m of Quatemary sediments comprising two marine Late Quaternary records: A 7 m marine unit (185.3-178.3 m) comprised the entire last interglacial, including its lower and upper transitions (Late Saalian-Eemian-Early Weichselian), while the upper 132 m of marine deposits covered the last about 15,000 years from the Late Weichselian through the Holocene, including the Pleistocene-Holocene transition. Results from the study of lithology, foraminifera, stable isotope measurements and radiocarbon dates are reviewed while emphasizing the most important contributions to the general understanding of the North Atlantic Quatemary history

scholarly journals Impact of dry intrusion events on the composition and mixing state of particles during the winter Aerosol and Cloud Experiment in the Eastern North Atlantic (ACE-ENA)

2021 ◽  
Vol 21 (24) ◽  
pp. 18123-18146
Author(s):  
Jay M. Tomlin ◽  
Kevin A. Jankowski ◽  
Daniel P. Veghte ◽  
Swarup China ◽  
Peiwen Wang ◽  
...  
Keyword(s):  
Long Range ◽  
North Atlantic ◽  
Cloud Condensation Nuclei ◽  
Aerosol Size Distribution ◽  
Condensation Nuclei ◽  
Mixing State ◽  
Carbonaceous Particles ◽  
X Ray ◽  
Eastern North Atlantic ◽  
Individual Particles

Abstract. Long-range transport of continental emissions has a far-reaching influence over remote regions, resulting in substantial change in the size, morphology, and composition of the local aerosol population and cloud condensation nuclei (CCN) budget. Here, we investigate the physicochemical properties of atmospheric particles collected on board a research aircraft flown over the Azores during the winter 2018 Aerosol and Cloud Experiment in the Eastern North Atlantic (ACE-ENA) campaign. Particles were collected within the marine boundary layer (MBL) and free troposphere (FT) after long-range atmospheric transport episodes facilitated by dry intrusion (DI) events. Chemical and physical properties of individual particles were investigated using complementary capabilities of computer-controlled scanning electron microscopy and X-ray spectromicroscopy to probe particle external and internal mixing state characteristics. Furthermore, real-time measurements of aerosol size distribution, cloud condensation nuclei (CCN) concentration, and back-trajectory calculations were utilized to help bring into context the findings from offline spectromicroscopy analysis. While carbonaceous particles were found to be the dominant particle type in the region, changes in the percent contribution of organics across the particle population (i.e., external mixing) shifted from 68 % to 43 % in the MBL and from 92 % to 46 % in FT samples during DI events. This change in carbonaceous contribution is counterbalanced by the increase in inorganics from 32 % to 57 % in the MBL and 8 % to 55 % in FT. The quantification of the organic volume fraction (OVF) of individual particles derived from X-ray spectromicroscopy, which relates to the multi-component internal composition of individual particles, showed a factor of 2.06 ± 0.16 and 1.11 ± 0.04 increase in the MBL and FT, respectively, among DI samples. We show that supplying particle OVF into the κ-Köhler equation can be used as a good approximation of field-measured in situ CCN concentrations. We also report changes in the κ values in the MBL from κMBL, non-DI=0.48 to κMBL, DI=0.41, while changes in the FT result in κFT, non-DI=0.36 to κFT, DI=0.33, which is consistent with enhancements in OVF followed by the DI episodes. Our observations suggest that entrainment of particles from long-range continental sources alters the mixing state population and CCN properties of aerosol in the region. The work presented here provides field observation data that can inform atmospheric models that simulate sources and particle composition in the eastern North Atlantic.

scholarly journals The silicon stable isotope distribution along the GEOVIDE section (GEOTRACES GA-01) of the North Atlantic Ocean

2018 ◽  
Vol 15 (18) ◽  
pp. 5663-5676 ◽  
Author(s):  
Jill N. Sutton ◽  
Gregory F. de Souza ◽  
Maribel I. García-Ibáñez ◽  
Christina L. De La Rocha
Keyword(s):  
Stable Isotope ◽  
Atlantic Ocean ◽  
North Atlantic ◽  
Deep Water ◽  
North Atlantic Ocean ◽  
Water Masses ◽  
Labrador Sea ◽  
The North ◽  
The North Atlantic ◽  
Eastern North Atlantic

Abstract. The stable isotope composition of dissolved silicon in seawater (δ30SiDSi) was examined at 10 stations along the GEOVIDE section (GEOTRACES GA-01), spanning the North Atlantic Ocean (40–60∘ N) and Labrador Sea. Variations in δ30SiDSi below 500 m were closely tied to the distribution of water masses. Higher δ30SiDSi values are associated with intermediate and deep water masses of northern Atlantic or Arctic Ocean origin, whilst lower δ30SiDSi values are associated with DSi-rich waters sourced ultimately from the Southern Ocean. Correspondingly, the lowest δ30SiDSi values were observed in the deep and abyssal eastern North Atlantic, where dense southern-sourced waters dominate. The extent to which the spreading of water masses influences the δ30SiDSi distribution is marked clearly by Labrador Sea Water (LSW), whose high δ30SiDSi signature is visible not only within its region of formation within the Labrador and Irminger seas, but also throughout the mid-depth western and eastern North Atlantic Ocean. Both δ30SiDSi and hydrographic parameters document the circulation of LSW into the eastern North Atlantic, where it overlies southern-sourced Lower Deep Water. The GEOVIDE δ30SiDSi distribution thus provides a clear view of the direct interaction between subpolar/polar water masses of northern and southern origin, and allow examination of the extent to which these far-field signals influence the local δ30SiDSi distribution.

Quaternary deep-sea ostracode taxonomy of Ocean Drilling Program Site 980, eastern North Atlantic Ocean

2014 ◽  
Vol 88 (4) ◽  
pp. 770-785 ◽  
Author(s):  
Moriaki Yasuhara ◽  
Hisayo Okahashi
Keyword(s):  
North Atlantic ◽  
Deep Sea ◽  
North Atlantic Ocean ◽  
Late Quaternary ◽  
Eastern Slope ◽  
Ocean Drilling Program ◽  
Ocean Drilling ◽  
Eastern North Atlantic ◽  
One New Species ◽  
Microscopy Images

Ocean Drilling Program (ODP) Holes 980 B and C, Feni Drift at the eastern slope of the Rockall Plateau, eastern North Atlantic, were examined for late Quaternary deep-sea ostracode taxonomy. Nineteen genera and 32 species were examined and (re-)illustrated with high-resolution scanning electron microscopy images. One new speciesCytheropteron paramassonin. sp. is described and one new nameEucytherura zehaliis proposed forEucytherura hazeliYasuhara et al., 2009. This study provides updated taxonomic information for deep-sea ostracode genera and species from the eastern North Atlantic, which is an important baseline for application of deep-sea ostracodes to paleoceanographical reconstructions and paleoecological studies in this region.

Sedimentary processes and the creation of the stratigraphic record in the Late Quaternary North Atlantic Ocean

1995 ◽  
Vol 348 (1324) ◽  
pp. 229-241 ◽  
Keyword(s):  
North Atlantic ◽  
North Atlantic Ocean ◽  
Late Quaternary ◽  
Turbidity Currents ◽  
Sedimentary Processes ◽  
Bottom Currents ◽  
The North ◽  
Sea Bed ◽  
Stratigraphic Record ◽  
Ice Rafting

The primary difficulty in the interpretation of the stratigraphic record is that a multiplicity of sedimentary processes, some producing similar effects, are responsible for it. We seek to unravel the effects of the more important processes through analysis of sedimentary properties. The effects to be unravelled are those relating to pelagic input (vertical flux) due to organic productivity, wind-blown dust, ice-rafting and volcanic ash; to horizontal flux in turbidity currents, debris flows, and nepheloid layers caused by the reworking of sea-bed sediments by internal waves and bottom currents; and to degradation of the record by dissolution, oxidation and mixing of components. Contrasting regions of the North Atlantic are used to show the effects of bottom currents, ice-rafting, wind and productivity on sediments. Applications to estimates of changes in bottom currents, productivity and carbon sequestration in the N.E. Atlantic over the past 30 ka are given.

scholarly journals Late Quaternary Pteropod Preservation in Eastern North Atlantic Sediments in Relation to Changing Climate

Radiocarbon ◽  
1991 ◽  
Vol 33 (3) ◽  
pp. 277-282 ◽  
Author(s):  
G. M. Ganssen ◽  
S. R. Troelstra ◽  
Klaas van der Borg ◽  
A. M. F. de Jong
Keyword(s):  
Climatic Change ◽  
North Atlantic ◽  
Deep Sea ◽  
Late Quaternary ◽  
Changing Climate ◽  
Eastern North Atlantic

AMS 14C measurements on pteropod shells from eastern North Atlantic deep-sea cores reveal distinct periods of aragonite preservation during the last 16,000 years. Most preservation spikes coincide with documented periods of climatic change on a scale of 2 × 101 to 2 × 103 years.

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