Encyclopedia of Marine Geosciences

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| Editors: Jan Harff, Martin Meschede, Sven Petersen, Jörn Thiede

Ice-Rafted Debris (IRD)

  • Antoon KuijpersEmail author
  • Paul Knutz
  • Matthias Moros
Living reference work entry
DOI: https://doi.org/10.1007/978-94-007-6644-0_182-1


Ocean Heat Transport Planktic Foraminifera Rafting Process Iceberg Calve Greenland Fjord 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Ice-rafted debris (IRD) is a terrigenous material transported within a matrix of ice and deposited in marine or lake sediments when the ice matrix melts (US National Climatic Data Center).

History of Observations

Coarse-grained clasts interpreted as ice-rafted debris were first recognized in seabed samples collected during a 1928 expedition of the US Coast Guard vessel “Marion” in the northern Labrador Sea and Baffin Bay (Ricketts and Trask, 1932). A decade later, Bramlette and Bradley (1940) described glacially transported striated clasts and erratics from North Atlantic seabed sediments. The more common use of IRD as a proxy of glacial variability commenced with the systematic sampling of deep-sea sediments in the early 1970s, notably by the international Deep Sea Drilling Programme (DSDP) and the “Vema” cruises operated from Lamont-Doherty Earth Observatory in the USA. Initially, IRD analyses were mainly applied to understand the long-term Cenozoic evolution of ice sheets (Berggren, 1972). This was highlighted by the study of Shackleton et al. (1984), who traced the development of major northern hemisphere glaciations back to about 2.5 Ma ago. A different approach demonstrated by, among others, Ruddiman (1977) was the application of ice-rafted sand-sized material measured in multiple core records to investigate late Quaternary ice dispersal patterns in the North Atlantic. In 1988, a milestone article by Hartmut Heinrich, reporting on the origin and consequences of late Quaternary cyclic ice rafting, set the stage for a new understanding of rapid ice sheet–ocean interactions during the last glacial in the North Atlantic region (Heinrich, 1988). Subsequent work by Andrews and Tedesco (1992) and Broecker et al. (1992) identified these ice rafting cycles (so-called Heinrich, H-events) as distinct layers rich in detrital carbonate derived from Paleozoic limestone formations in the Hudson Bay region, thus pointing to the Laurentide Ice Sheet (LIS) as the main iceberg source. Heinrich (1988) documented that these cyclic layers were marked by their high lithic-to-foraminifera ratio and increased relative abundance of the polar planktic foraminifera N. pachyderma sinistral with low δ18O values indicative of low-salinity polar water. Bond et al. (1997) noted the carbonate-rich layers to have a sharp basal contact suggesting short-lived, catastrophic discharges of icebergs from the LIS. These IRD horizons are widely distributed in late Quaternary North Atlantic sediments between 40o and 55° N, occurring with intervals of about 7,000 years that partly correspond to shorter (<1,000 year), but intense cooling periods in Greenland ice core records (Bond and Lotti, 1995). The geochemical composition of the Heinrich layers shows a Hudson Strait source for H1, H2, H4, and H5, but chemical and mineralogical analyses suggest another source for H3 (Gwiazda et al., 1996). Since the mid-1990s, numerous paleoceanographic studies have utilized IRD to document regional and temporal ice sheet variability and the effect of meltwater on ocean thermohaline circulation (e.g., Vidal et al., 1997; Knutz et al., 2002). In the past decade, focus on the topic has further increased due to the ongoing debate on climate warming, Antarctic and Greenland Ice Sheet stability, and implications for sea level rise and ocean circulation.

Ice Rafting Processes and IRD Analysis

Icebergs form the primary transport agent for IRD (Fig. 1), but sediments can also be carried by sea ice drift. Even when using detailed IRD analytical techniques, it appears difficult to distinguish between these two transport mechanisms (Tantillo et al., 2012). The sediment load of individual icebergs depends on the basal (cold-based versus warm-based) thermal regime of the glacier from which the iceberg has calved (Drewry, 1986). Aeolian deposition and rock fall from exposed, ice-free cliffs are other mechanisms supplying IRD load to glaciers. Sea ice-derived IRD originates from seabed grounding and beach contact processes as well as wind-blown depositions (Gilbert, 1990). Ice melting and rafting processes and subsequent deposition of IRD is largely a function of ambient ocean water temperatures. Although there is no standard technique for IRD analyses, the proxy is commonly measured as the number of detrital grains in the >150 μm size fraction per gram bulk sediment (dry weight). Another approach is simply to define IRD as weight percentage of material with grain sizes larger than coarse silt (>63 μm). These thresholds are arbitrary, since all grain sizes, from clay to boulder size, may potentially be ice rafted. In proximal glacimarine environments, the finer grain sizes generally make up the largest amount of glacially derived sediments. X-ray analysis of intact sediment cores is often used for counts of larger-sized (e.g., gravel) IRD components.
Fig. 1

Example of drifting ice transporting a significant load of land-derived sediments which is being deposited on the seabed as “IRD” as a result of the ice melting process (Photo courtesy J.T. Andrews, INSTAAR, Boulder, Colorado)

Sources and Distribution of IRD

IRD is not only present close to formerly glaciated continental margins, but has been found widespread in the subpolar North Atlantic, and occasionally even further south, i.e., in the eastern North Atlantic off the Strait of Gibraltar. Studies of North Atlantic glacial IRD provenance have provided important information on the relative contributions of the Laurentide, Greenland, and NW European ice sheets. During H-events 1 and 2, ice discharge from Hudson Strait contributed with large amounts of detrital carbonate, at approx. 14,500 and 20,000 14C year BP, respectively. (Andrews and Tedesco, 1992; Broecker et al., 1992). Furthermore, H-event layers contain igneous fragments of hornblende and feldspar displaying a dominant Paleoproterozoic (1,600–1,800 Ma) provenance age (Hemming et al., 1998), which is consistent with a Laurentide Ice Sheet (LIS) origin. On the other hand, IRD showing younger isotopic ages and containing chalk coccoliths are inferred to have been derived from NW European glacial outlets (Scourse et al., 2000). These isotopic and mineralogical fingerprints of European/Scandinavian derived icebergs appear to have formed precursors to the main LIS response, thus adding to the complexity of H-events. A possible IRD contribution to H-events by icebergs from the Greenland Ice Sheet has been a matter of discussion. Despite the scarcity of high-resolution records from the Greenland margin and lack of consistent chronological framework, some studies show that Greenland Ice Sheet iceberg calving events occurred more frequently than H-events (Stein et al., 1996; Andrews, 2000). An independent behavior of the Greenland Ice Sheet during the last deglaciation has been shown by Knutz et al. (2011) and is illustrated by the vast amount of continental ice still present in Greenland today. Timing of iceberg surging stages on the NW European margin reflects also here different ice sheet behaviors before and during Heinrich events (Scourse et al., 2000; Knutz et al., 2002). The arrival of European and Icelandic detritus preceding the deposition of detrital carbonate-rich debris from the LIS (Bond et al., 1999; Grousset et al., 2001) further support the conclusions by Dowdeswell et al. (1999) that the dynamics of Quaternary ice sheets surrounding the Nordic Seas and North Atlantic were asynchronous. This implies that each glaciated margin may have behaved differently in response to external ocean–climate forcing.

Iceberg Surging Mechanisms

Since the early 1990s, several possible mechanisms responsible for forcing large-scale IRD events have been proposed (e.g., Alley and Clark, 1999). The binge–purge hypothesis of MacAyeal (1993) invoked internal ice sheet dynamics as a driver for H-events. However, this mechanism is not supported by the detailed structure of H-events and cannot explain North Atlantic records showing millennial and centennial scale IRD fluctuations that appear to be closely coupled to the ocean–atmosphere climate system (e.g., Bond and Lotti, 1995). Apart from internal ice sheet dynamics, ocean circulation changes, sea level fluctuations, variations in solar parameters, as well as ice-load-induced earthquakes have been proposed being responsible for iceberg surging. In addition, Hulbe et al. (2004) postulate catastrophic ice shelf breakup induced by climate-controlled meltwater infilling of surface crevasses as recently witnessed along the Antarctic Peninsula. Observations of recent iceberg discharge processes and ice rafting in an east Greenland fjord reported by Reeh et al. (1999) demonstrated that the transport and deposition of iceberg-derived IRD increased in periods of enhanced (subsurface) advection of “warm” Atlantic water. These findings were used in a study by Moros et al. (2002) and Kuijpers et al. (2005) who concluded that large-scale IRD events in the North Atlantic most likely were triggered by enhanced northward ocean heat transport which caused bottom melting of floating outlet glaciers and ice shelves, leading to ice sheet destabilization and iceberg surging. More recently, a sudden acceleration, thinning, and retreat of the Jakobshavn Isbræ, west Greenland, were observed, which have been attributed to the warming of the subsurface ocean currents off west Greenland (Holland et al., 2008). Studies of sedimentary records of the past ca. 100 years from this area and from another active glacier calving site on the southeast Greenland coast (Lloyd et al., 2011; Andresen et al., 2012) have meanwhile confirmed a correlation between enhanced ocean subsurface warming and associated glacier bottom melting and increase in glacier acceleration and iceberg IRD production. It is without doubt that also the other factors referred to above as, for instance, surface (air) temperature warming and ice sheet dynamics, influence iceberg calving activity. However, increasing evidence has demonstrated the important role of ocean (sub)surface warming when trying to explain iceberg surging over larger areas, such as during the Heinrich events (e.g., Alvares-Solas et al., 2010), or more locally, as recently observed in South Greenland fjords. Within this context, one should keep in mind that ocean heat transport pathways are influencing the temperature regime of various parts of the North Atlantic not everywhere in the same way, which may be one of the reasons for reported asynchronous behavior of glacial ice sheets. The occurrence of iceberg-derived IRD in sedimentary records thus not only provides a tool to reconstruct former ice sheet dynamics, glacier calving activity, and iceberg drift but also yields information on ocean current patterns. In addition, having a different origin and a distribution pattern more depending on atmospheric circulation, sea ice-derived IRD can provide additional information for assessing prevailing wind directions and albedo conditions.


IRD has been found to be widely distributed in the entire subpolar North Atlantic. Glacial sedimentary records from this region display discrete IRD layers at time intervals of about 7,000 years named “Heinrich” layers that witness large-scale iceberg surging of the North American Laurentide Ice Sheet. This conclusion was made based on the lithology of the IRD involved, showing, among others, a large contribution of detrital dolomitic carbonate derived from the sedimentary rocks around Hudson Bay and Strait. Mineral studies have provided also evidence for IRD originating from European and Greenland glaciers. Asynchronous deposition of IRD from these various sources suggests a different stability regime of ice sheets west and east of the North Atlantic. Although several mechanisms may have played a role, increasing evidence arises which demonstrates that (sub)surface ocean warming and associated bottom melting of floating glaciers and ice shelves have been an important mechanism triggering large-scale iceberg calving (“Heinrich”) events, both under glacial climate and under present-day warming conditions.



  1. Alley, R. B., and Clark, P. U., 1999. The deglaciation of the Northern Hemisphere: a global perspective. Annual Review of Earth and Planetary Sciences, 27, 149–182.CrossRefGoogle Scholar
  2. Alvares-Solas, J., Charbit, S., Ritz, C., Paillard, D., Ramstein, G., and Dumas, C., 2010. Links between ocean temperature and iceberg discharge during Heinrich events. Nature Geoscience, 3, 122–126.CrossRefGoogle Scholar
  3. Andresen, C. S., Straneo, F., Ribergaard, M. H., Bjørk, A. A., Andersen, T. J., Kuijpers, A., Nørgaard-Pedersen, N., Kjær, K., Schjøth, F., Weckström, K., and Ahlstrøm, A. P., 2012. Rapid response of Helheim Glacier in Greenland to climate variability over the past century. Nature Geoscience, 5, 37–41.CrossRefGoogle Scholar
  4. Andrews, J. T., 2000. Icebergs and iceberg rafted detritus (IRD) in the North Atlantic: facts and assumptions. Oceanography, 13(3), 100–108.CrossRefGoogle Scholar
  5. Andrews, J. T., and Tedesco, K., 1992. Detrital carbonate-rich sediments, northwest Labrador Sea: implications for ice-sheet dynamics and iceberg rafting (Heinrich) events in the North Atlantic. Geology, 20, 1087–1090.CrossRefGoogle Scholar
  6. Berggren, W. A., 1972. Late Pliocene-Pleistocene glaciation. In Laughton, A. S., Berggren, W. A., et al. (eds.), Initial Reports of the Deep-Sea Drilling Programme. Washington, DC: US Government Printing Office, Vol. 12, pp. 953–963.Google Scholar
  7. Bond, G. C., and Lotti, R., 1995. Iceberg discharges into the North Atlantic on millennial time scales during the Last Glaciation. Science, 267, 1005–1009.CrossRefGoogle Scholar
  8. Bond, G., Showers, W., Cheseby, M., Lotti, R., Almasi, P., deMenocal, P., Priore, P., Cullen, H., Hajdas, I., and Bonani, G., 1997. A pervasive millennial-scale cycle in North Atlantic Holocene and glacial climates. Science, 278, 1257–1266.CrossRefGoogle Scholar
  9. Bond, G., Showers, W., Elliot, M., Evans, M., Lotti, R., Hadjas, I., Bonani, G., and Johnson, S., 1999. The North Atlantic’s 1–2 kyr climate rhythm: relation to Heinrich events, Dansgaard/Oeschger and the Little Ice Age. In Clark, P. U., et al. (eds.), Mechanisms of Global Climate Changes at Millennial Timescales. Washington, DC: AGU. Geophysical Monograph Series, 112, pp. 35–58.CrossRefGoogle Scholar
  10. Bramlette, M. N., and Bradley, W. H., 1940. Geology and biology of North Atlantic deep-sea cores between Newfoundland and Ireland. Part I. Lithology and geological interpretations. United States Geological Survey, Professional Paper 196A: 1–34.Google Scholar
  11. Broecker, W. S., 1994. Massive iceberg discharges as triggers for global climate change. Nature, 372, 421–424.CrossRefGoogle Scholar
  12. Broecker, W. S., Bond, G., McManus, J., Klas, M., and Clark, M., 1992. Origin of the Northern Atlantic’s Heinrich events. Climate Dynamics, 6, 265–273.CrossRefGoogle Scholar
  13. 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, 301–304.CrossRefGoogle Scholar
  14. Dowdeswell, J. A., Elverhøj, A., Andrews, J. T., and Hebbeln, D., 1999. Asynchronous deposition of ice-rafted layers in the Nordic seas and North Atlantic Ocean. Nature, 400, 348–351.CrossRefGoogle Scholar
  15. Drewry, D., 1986. Glacial Geologic Processes. London: Edward Arnold.Google Scholar
  16. Gilbert, R., 1990. Rafting in glacimarine environments. In Dowdeswell, J. A., and Scource, J. D. (eds.), Glacimarine Environments: Processes and Sediments. London: Geological Society. Special Publications of the Geological Society of London, Vol. 53, pp. 105–120.Google Scholar
  17. Grousset, F. E., Cortijo, E., Huon, S., Herve, L., Richter, T., Burdloff, D., Duprat, J., and Weber, O., 2001. Zooming in on Heinrich layers. Paleoceanography, 16, 240–259.CrossRefGoogle Scholar
  18. Gwiazda, R. H., Hemming, S. R., and Broecker, W. S., 1996. Provenance of icebergs during Heinrich event 3 and their contrast to their sources during other Heinrich episodes. Paleoceanography, 11, 371–378.CrossRefGoogle Scholar
  19. Heinrich, H., 1988. Origin and consequences of cyclic ice rafting in the Northeast Atlantic Ocean during the past 130,000 years. Quaternary Research, 29(2), 143–152.CrossRefGoogle Scholar
  20. Hemming, S. R., Broecker, W. S., Sharp, W. D., Bond, G. C., Gwiadzda, R. H., McManus, J. F., Klas, M., and Hajdas, I., 1998. Provenance of Heinrich layers in core V28-82, northwestern Atlantic: 40Ar/39Ar ages of ice-rafted hornblende, Pb isotopes in feldspar grains, and Nd-Sr-Pb isotopes in the fine sediment fraction. Earth and Planetary Science Letters, 164, 317–333.CrossRefGoogle Scholar
  21. Holland, D., Thomas, R. H., de Young, B., Ribergaard, M. H., and Lyberth, B., 2008. Acceleration of Jakobshavn Isbrae triggered by warm subsurface ocean waters. Nature Geoscience, 1, 659–664.CrossRefGoogle Scholar
  22. Hulbe, C. L., MacAyeal, D. R., Denton, G. H., Kleman, J., and Lowell, T. V., 2004. Catastrophic ice shelf breakup as the source of Heinrich event icebergs. Paleoceanography, 19, PA1004, doi:10.1029/2003PA000890.CrossRefGoogle Scholar
  23. Knutz, P. C., Hall, I. R., Zahn, R., Rasmussen, T. L., Kuijpers, A., Moros, M., and Shackleton, N. J., 2002. Multidecadal ocean variability and NW European ice sheet surges during the last deglaciation. Geochemistry, Geophysics, Geosystems, 3(12), 1–9.CrossRefGoogle Scholar
  24. Knutz, P. C., Ebbesen, H., Christiansen, S., Sicre, M.-A., and Kuijpers, A., 2011. A triple stage deglacial retreat of the southern Greenland Ice Sheet driven by vigorous Irminger Current. Paleoceanography, 26, PA3204, doi:10.1029/2010PA002053.CrossRefGoogle Scholar
  25. Kuijpers, A., Heinrich, H., and Moros, M., 2005. Climatic warming: a trigger for glacial iceberg surges (“Heinrich events”) in the North Atlantic? Review of Survey Activities. Geological Survey of Denmark and Greenland Bulletin, 7, 53–56.Google Scholar
  26. Linthout, K., Troelstra, S. R., and Kuijpers, A., 2000. Provenance of coarse Ice Rafted Detritus near the SE Greenland Margin. Netherlands Journal of Geosciences, 79(1), 109–121.Google Scholar
  27. Lloyd, J. M., Moros, M., Perner, K., Telford, R., Kuijpers, A., Jansen, E., and McCarthy, D., 2011. A 100 year record of ocean temperature control on the stability of Jakobshavn Isbrae, West Greenland. Geology, doi:10.1130/G32076.1.Google Scholar
  28. MacAyeal, D. R., 1993. Binge/purge oscillations of the Laurentide ice sheet as a cause of the North Atlantic’s Heinrich events. Paleoceanography, 8, 775–784.CrossRefGoogle Scholar
  29. Moros, M., Kuijpers, A., Snowball, I., Lassen, S., Bäckström, D., Gingele, F., and McManus, J., 2002. Were glacial iceberg surges in the North Atlantic triggered by climatic warming? Marine Geology, 192, 393–417.CrossRefGoogle Scholar
  30. Reeh, N., Mayer, C., Miller, H., Højmark-Thomsen, H., and Weidick, A., 1999. Present and past climate control on fjord glaciations in Greenland: implications for IRD deposition in the sea. Geophysical Research Letters, 26, 1039–1042.CrossRefGoogle Scholar
  31. Ricketts, N. G., and Trask, P. D., 1932. The “Marion” expedition to Davis Strait and Baffin Bay, 1928 – Scientific Results, Part 1, The Bathymetry and Sediments of Davis Strait. Washington, DC: United States Government Printing Office. U.S. Treasury Department, Coast Guard Bulletin, Vol. 19, pp. 1–81.Google Scholar
  32. Ruddiman, W. F., 1977. Late Quaternary deposition of ice-rafted sand in the sub-polar North Atlantic (40–60o N). Geological Society of America Bulletin, 88, 1813–1827.CrossRefGoogle Scholar
  33. Scourse, J. D., Hall, I. R., McCave, I. N., Young, J. R., and Sudgon, C., 2000. The origin of Heinrich layers: evidence from H2 for European precursor events. Earth and Planetary Science Letters, 181, 187–195.CrossRefGoogle Scholar
  34. Shackleton, N. J., Backman, J., Zimmerman, H., Kent, D. V., Hall, M. A., Roberts, D. G., Schnitker, D., Baldauf, J. G., Desprairies, A., Homrighausen, R., Huddlestun, P., Keene, J. B., Kaltenback, A. J., Krumsiek, K. A. O., Morton, A. C., Murray, J. W., and Westberg-Smith, J., 1984. Oxygen isotope calibration of the onset of ice rafting and history of glaciation in the North Atlantic region. Nature, 307, 620–623.CrossRefGoogle Scholar
  35. Stein, R., Nam, S.-I., Grobe, H., and Hubberten, H., 1996. Late Quaternary glacial history and short-term ice-rafted debris fluctuations along the East Greenland continental margin. In Andrews, J. T., Austin, W. E. N., Bergsten, H., and Jennings, A. E. (eds.), Late Quaternary Palaeoceanography of the North Atlantic Margins. London: Geological Society. Geological Society Special Publication, Vol. 111, pp. 135–151.Google Scholar
  36. Tantillo, B., St. John, K., Passchier, S., and Kearns, L., 2012. Can sea ice-rafted debris be distinguished from iceberg-rafted debris based on grain surface features? Analysis of quartz grains from modern Arctic Ocean sea ice floes. In GSA Annual Meeting Abstracts.Google Scholar
  37. Vidal, L., Labeyrie, L., Cortijo, E., Arnold, M., Duplessy, J. C., Michel, E., and Becqué, S., 1997. Evidence for changes in the North Atlantic Deep Water linked to meltwater surges during the Heinrich events. Earth and Planetary Science Letters, 146, 13–27.CrossRefGoogle Scholar

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© Springer Science+Business Media Dordrecht 2014

Authors and Affiliations

  1. 1.Geological Survey of Denmark and Greenland (GEUS)CopenhagenDenmark
  2. 2.Leibniz Institute for Baltic Sea Research Warnemünde (IOW)RostockGermany