I
ICE-RAFTED DEBRIS (IRD)
Antoon Kuijpers
1
, Paul Knutz
1 and Matthias Moros
2
1
Geological Survey of Denmark and Greenland (GEUS),
Copenhagen, Denmark
2
Leibniz Institute for Baltic Sea Research Warnemünde,
Rostock, Germany
Definition
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 d
18
O 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 40
o
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.
J. Harff et al. (eds.), Encyclopedia of Marine Geosciences, DOI 10.1007/978-94-007-6238-1,
© Springer Science+Business Media Dordrecht 2016
ICE-RAFTED DEBRIS (IRD)
Antoon Kuijpers
1
, Paul Knutz
1 and Matthias Moros
2
1
Geological Survey of Denmark and Greenland (GEUS),
Copenhagen, Denmark
2
Leibniz Institute for Baltic Sea Research Warnemünde,
Rostock, Germany
Definition
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 d
18
O 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 40
o
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.
J. Harff et al. (eds.), Encyclopedia of Marine Geosciences, DOI 10.1007/978-94-007-6238-1,
© Springer Science+Business Media Dordrecht 2016