Skip to main content Accessibility help
×
Home

Evidence from 40Ar/39Ar Ages for a Churchill province source of ice-rafted amphiboles in Heinrich layer 2

  • Roberto H. Gwiazda (a1), Sidney R. Hemming (a1), Wallace S. Broecker (a1), Tullis Onsttot (a2) and Chris Mueller (a2)...

Abstract

40Ar/39Ar ages of most single ice-ratted amphiboles from Heinrich layer 2 (H2) from a core in the Labrador Sea, a core in the eastern North Atlantic and a core in the western North Atlantic range from 1600 to 2000 Ma. This range is identical to that for K/Ar ages from the Churchill province of the Canadian Shield that outcrops at Hudson Strait and forms the basement of the northern part of Hudson Bay. The ambient glacial sediment includes some younger and older grains derived from Paleozoic, Mesoproterozoic and Archean sources, but still the majority of the amphiboles have ages in the 1600–2000 Ma interval. The Ca/K ratios of these 1600–2000 Ma old amphiboles, however, have a bimodal distribution in contrast with the uniformity of the Ca/K ratios of H2 amphiboles. This indicates that 1600–2000 Ma old amphiboles of the ambient sediment were derived from an additional Early Proterozoic source besides Churchill province. In H2, Churchill-derived grains constitute 20–40% of the ice-rafted debris (IRD). The fraction in the ambient glacial sediment is 65–80%. Results presented here are consistent with the hypothesis that Heinrich events were produced by a sudden intensification of the iceberg discharge through Hudson Strait that mixed, in the North Atlantic, with icebergs that continued to calve from other ice sheets. The shift from mixed sources in the background sediment to a large dominance of Churchill province grains in H2 indicates that, even if calving of other ice sheets intensified during the Heinrich episode, the increase in the iceberg discharge via Hudson Strait from the Hudson Bay drainage basin of the Laurentide ice sheet was by far the largest.

  • View HTML
    • Send article to Kindle

      To send this article to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about sending to your Kindle. Find out more about sending to your Kindle.

      Note you can select to send to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

      Find out more about the Kindle Personal Document Service.

      Evidence from 40Ar/39Ar Ages for a Churchill province source of ice-rafted amphiboles in Heinrich layer 2
      Available formats
      ×

      Send article to Dropbox

      To send this article to your Dropbox account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Dropbox.

      Evidence from 40Ar/39Ar Ages for a Churchill province source of ice-rafted amphiboles in Heinrich layer 2
      Available formats
      ×

      Send article to Google Drive

      To send this article to your Google Drive account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Google Drive.

      Evidence from 40Ar/39Ar Ages for a Churchill province source of ice-rafted amphiboles in Heinrich layer 2
      Available formats
      ×

Copyright

References

Hide All
Alley,, R. B. and MacAyeal,, D. R. 1994. Ice-rafted debris associated with binge/purge oscillations of the Laurentide ice sheet. Paleoceanography, 9 (4), 503511.
Andrews,, J. T. and Tedesco, K. 1992. Detrital carbunate-rich sediments, northwestern Labrador Sea: implications for ice-sheet dynamics and iceberg rafting (Heinrich) events in the North Atlantic. Geology, 20 (12), 10871090.
Bond,, G. C. 1991. Heinrich events — a consequence of sea-level rises? [Abstract.] EOS. 75 (16), Supplement, 54.
Bond,, G. C. and Lotti, R. 1995. Iceberg discharges into the North Atlantic on millennial time scales during the last glaciation. Science, 267 (5200), 10051010.
Bond,, G. and 13 others. 1992. Evidence for massive discharges of icebergs into the North Atlantic Ocean during the last glacial period. Nature, 360 (6401), 245249.
Bond,, G. and 6 other. 1993. Correlations between climate records from North Atlantic sediments and Greenland ice. Nature, 265 (6442), 143147.
Broecker,, W. S., Bond,, G. C., Klas,, M. Clark, E. and McManus, J. 1992. Origin of the Northern Atlantic’s Heinrich events, Clim. Dyn., 6, 265273.
Condie,, K. C. 1990. Growth and accretion of continental crust: inferences based on Laurentia. Chem. Geol., 83. 183191.
Clumbest,, R. J., Johnson,, E.L. and Onstott., T. С. 1994. Compositon of metamorphic fluids, implication for 40Ar/39Ar geochronology, Geological Society of America Bulletin, 106, 942951.
Dowdeswell,, J. A., Maslin,, M. A. Andrews,, J. T. and McCave,, I. N. 1995. Iceberg production, debris rafting, and the extent and thickness of Heinrich layers (H-1, H-2) in North Atlantic sediments. Geology, 23 (4), 301304.
Easton,, R. M. 1986. Geochronology of the Grenville Province, In Moore,, J. M., Davidson, A. and Baer,, A. J., eds. The Grenville Province. St Johns, Nfld, Geological Association of Canada, 127173. (GSA Special Publication 31.)
Francois,, R. and Bacon,, M. P. 1994. Heinrich events in the North Atlantic: radiochemical evidence. Deep-Sea Res., Ser. I, 41, 315334.
Fronval,, T., Jansen,, E. Bloemcndal, J. and Johnsen, S. 1995. Oceanic evidence for coherent fluctuations in Fennoscandian and Laurentide ice sheets on millennium timescales. Nature, 374 (6521), 443446.
Grousset,, F. E. and 7 others. 1993. Patterns of ice-rafted detritus in the glacial North Atlantic (40–55°N). Paleoceanography, 8 (2), 175192.
Gwiazda,, R. H., Hemming,, S. R. and Broecker,, W. S. 1996. Tracking the sources of icebergs with lead isotopes: the provenance of ice-rafted debris in Heinrich Layer 2. Paleoceanography, 11 (1), 7793.
Heinrieh,, H. 1988. Origin and consequences of cyclic ice rafting in the northwest Atlantic Ocean during the past 130,000 years, Quat. Res., 29. 142152.
Higgins,, S. M., Anderson,, R. F., McManus,, J. F. and Fleisher,, M. Q. 1995. A high-resolution 10Be/230 Th study of Heinrich events over the last 30 kyr in a North Atlantic deep sea core. [Abstract.] EOS, 76 (17), Supplement, S170.
Hoffman,, P. F. 1989. Precambrian geology and tectonic history of North America. In Bally,, A. W. and Palmer,, A. R., eds. The geology of Aorth America — an overview. Boulder, CO, The Geological Society of America, 147512. (The Geology of North America 4.)
Huon,, S. and Jantschik, R. 1993. Detrital silicates in northeast Atlantic deep-sea sediments during the Late Quaternary: major element, REE and Rb-Sr isotopic data. Eclogae Geol. Helv., 86 (1), 195218.
Huon,, S. and Ruch, P. 1992. Mineralogical, K-Ar and 87Sr/86Sr isotope study of Holocene and last glacial sediments in a deep-sea core from the northeast Atlantic Ocean. Mar. Geol., 107, 275282.
Jantschik,, R. and Huon, S. 1992. Detrital silicates in northeast Atlantic deep-sea sediments during the Late Quaternary: mineralogical and K-Ar isotopic data. Eclogae Geol. Helv., 85 (1), 195212.
Keigwin,, L. D. and Lehman,, S. J. 1994. Deep circulation changes linked to Heinrich event 1 and Younger Dryas in a middepth North Atlantic corе. Paleoceanography, 9 (2), 185194.
MacAyeal,, D. R. 1993a. A low-order model of the Heinrich event cycle. Paleoceanography, 8 (6), 767773.
MacAyeal,, D. R. 1993b. Binge/purge oscillations of the Laurentide ice sheet as a cause of the North Atlantic’s Heinrich events. Paleoceanography, 8 (6), 775784.
McCulloch,, M. T. and Wasserburg,, G. T. 1978. Sm-Nd and Rb-Sr chronology of continental crust formation. Science,200, 10031011.
Noether,, G. E. 1976. Introduction to statistics, a non parametric approach. Second edition. Boston. Houghton Mifflin.
Ozard,, J. M., Slawson,, W. F. and Russell,, R. D. 1973. An integrated model for the lead isotopic evoluation for samples from the Canadian Shield. Can. J. Earth Sci., 10 (4), 529537.
Revel,, M., Sinko,, J. A. and Grousset,, F. E. 1996. Sr and Nd isotopes as tracers of North Atlantic lithic particles: paleoclimatic implications. Paleoceanography, 11 (1), 95113.
Rommer,, R. F. and Wright,, J. E. 1993. Lead mobilization during tectonic reactivation of the western Baltic Shield. Geochim. Cosmochim. Acta,57, 25552570.
Ruddiman,, W. F. 1977. Late Quaternary deposition of ice-rafted sand in the subpolar North Atlantic (lat 40 to 65°N). Geol. Soc. Am. Bull., 88 (12), 1813−1827.
Sachs,, L. 1984. Applied statistics: a handbook of techniques. Second edition. New York, Springer-Verlag.
Samson,, S. D. and Alexander,, E. G. Jr., 1987. Calibration of the interlaboratory 40Ar-39 Ar dating standard, Mmhb-1. Chem. Geol.,66, 2734.
Siegel,, S. 1956. Non parametric statistics for the behavioral sciences. New York, McGraw-Hill.
Verbitsky,, M. Y. and Saltzman, B. 1995. A diagnostic analysis of Heinrich-event glacial surges. Paleoceanography, 10 (1). 5965.

Metrics

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed