Skip to main content
×
Home
    • Aa
    • Aa

Subpolar North Atlantic Circulation at 9300 yr BP: Faunal Evidence

Abstract

We have examined the circulation of the subpolar North Atlantic at 9300 yr BP by using a dispersed layer of silicic volcanic ash as a synchronous horizon. At the level of this datum, we have reconstructed from foraminiferal evidence a geologically synoptic view of seasonal variations in sea-surface temperatures and salinities. The reconstruction defines two oceanic fronts at 9300 yr BP: (1) the meridionally oriented Polar Front bordering the axis of deglacial outflow of Arctic and Laurentide ice and meltwater and (2) a zonal portion of the Subarctic Convergence along 48° N, marking a major confluence between the subtropical and subpolar gyres. The 9300-yr configuration primarily differed from the modern pattern in the more easterly position (by 3°) of the Polar Front and the more southerly (3°) and easterly (5°) position of the Subarctic Convergene. Both fronts had been merged at 18,000 yr BP into the full-glacial Polar Front; at 9300 yr BP, they were approaching the end of a northwestward deglacial retreat toward the modern interglacial positions.

There were two dominant departures at 9300 yr BP from the Earth's modern configuration, both related to deglaciation: the very large Laurentide Ice Sheet still covering eastern North America to 48° N, and the region of cold Arctic/Laurentide deglacial outflow. These two features caused: a more easterly position than now of the region of upper air divergence and lower air convergence downstream from the Ice Sheet and meltwater outflow; a more intense expression of this upper air divergence and lower air convergence over the central portion of the subpolar North Atlantic; and a latitudinally more stable axis of convergence of surface westerlies over this region. These factors apparently caused the stronger oceanic convergence along 48°N than at present. They also created a stronger, southeastward-directed wind drift current, which opposed the meridional (northward) flow typical of the present interglaciation.

Copyright
Linked references
Hide All

This list contains references from the content that can be linked to their source. For a full set of references and notes please see the PDF or HTML where available.

J.T. Andrews , (1973). The Wisconsin Laurentide Ice sheet: dispersal centers, problems of rates of retreat and climatic implications. Arctic Alpine Research 5, 185199.

W.H. Berger , (1970). Planktonic foraminifera: Selective solution and the lysocline. Marine Geology 8, 111138.

R.A. Bryson , W.M. Wendland , J.D. Ives , J.T. Andrews , (1969). Radiocarbon isochrones on the disintegration of the Laurentide Ice Sheet. Arctic Alpine Research 1, 114.

H.H. Lamb , (1955). Two-way relationships between the snow or ice limit and 1000-500 mb thicknesses in the overlying atmosphere. Quarterly Journal of the Royal Meteorological Society 81, 172189.

H.H. Lamb , (1971). Climates and circulation regimes developed over the northern hemisphere during and since the last ice age. Paleogeography, Paleoclimatology, and Paleoecology 10, 125162.

H.H. Lamb , A. Woodroffe , (1970). Atmospheric circulation during the last Ice Age. Quaternary Research 1, 2958.

G. Manley , (1951). The range of variation of the British climate. Geographical Journal 117, 4368.

W.H. Munk , (1950). On the wind-driven ocean circulation. Journal of Meteorology 7, 7993.

G. Neumann , (1960). On the effect of bottom topography on ocean currents. Deutsche Hydrografika Zeitschrift 13, 132140.

W.F. Ruddiman , L.K. Glover , (1972). Vertical mixing of ice-rafted volcanic ash in North Atlantic sediments. Geological Society of America Bulletin 83, 28172836.

W.F. Ruddiman , A. McIntyre , (1973). Time-transgressive deglacial retreat of Polar Water from the North Atlantic. Quaternary Research 3, 117130.

C. Sancetta , J. Imbrie , N.G. Kipp , (1973). Climatic record of the past 130,000 years in North Atlantic deep sea cove V23-82: Correlation with the terrestrial record. Quaternary Research 3, 110116.

D.S. Tolderlund , A.W.H. , (1971). Seasonal distribution of planktonic foraminifera in the western North Atlantic. Micropaleontology 17, 297329.

Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Quaternary Research
  • ISSN: 0033-5894
  • EISSN: 1096-0287
  • URL: /core/journals/quaternary-research
Please enter your name
Please enter a valid email address
Who would you like to send this to? *
×

Metrics

Abstract views

Total abstract views: 16 *
Loading metrics...

* Views captured on Cambridge Core between 20th January 2017 - 28th April 2017. This data will be updated every 24 hours.