424
Frank et al.
rent speed. Higher amounts of focussed sediment
may be caused by a local decrease in current speed,
and consequently decreased capacity of the bottom current to carry particles due to its lower energy. However, it may also point to a larger or more
distant source area in the case of higher current
speed. An unambiguous interpretation ofthe changing redistribution intensity would only be possible
if winnowing had increased, which is a clear indication of higher current speeds. This problem could
be resolved by detailed grain size analyses of all
these cores which are not available at the moment.
In addition, a higher data density is required before
any reliable conclusions may be drawn from such
a map, but nevertheless this preliminary compilation suggests that there is some potential for future
studies.
Acknowledgments
This study was supported by two grants (Ma82 11
9-1; 9-3) of the Deutsche Forschungsgemeinschaft (DFG) to M. F. This research was funded
by the Deutsche F orschungsgemeinschaft (Sonderforschungsbereich 261 at Bremen University,
Contribution No. 176). Data are available under
www.pangaea.de/Projects/SFB261.
References
Abelmann A, Gersonde R (1991) Biosiliceous particle
flux in the Southern Ocean. Mar Chern 35: 503-536
Anderson JB (1990) Sediments. In: Glasby GP (ed)
Antarctic sector of the Pacific. Oceanogr Ser Vol 51 ,
Elsevier, New York, pp 187-205
Anderson RF, Bacon MP, Brewer PG (1983) Removal of
230Th and 2JJPa from the open ocean. Earth Planet Sci
Lett 62: 7-23
Asmus T, Frank M, Koschrnieder C, Frank N, Gersonde
R, Kuhn G, Mangini A (1999) Biogenic particle flux at
the southern Atlantic section of the Subantarctic
Front during the late Quaternary: Evidence from sedimentary 23i Pa and 230Th . Mar Geol, in press
Bacon MP, Rosh~lt IN (1982) Accumulation rates of
DOTh and 231 Pa and some transition metals on the
BermudaRise. Geochim Cosmochim Acta 46: 651-666
Bacon MP (1984) Glacial to interglacial changes in carbonate and clay sedimentation in the Atlantic estimated from thorium-230 measurements. Isot Geosci
2:97-111
Bennekom AJ van, Berger GW, van der Gaast SJ, De
Vries RTP (1988) Primary productivity and the silica
cycle in the in the southern ocean (Atlantic Sector).
Paleogeogr Paleoclimatol Paleoecol67: 19-30
Berger WH, Smetacek V, Wefer G (1989) Productivity of
the ocean: Present and past. In: Berger WH,
Smetacek V and Wefer G (eds) Productivity of the
Ocean: Present and Past. Dahlem Workshop Reports,
J Wiley & Sons, Chichester, pp 1-34
Broecker WS (1982) Glacial to interglacial changes in
ocean chemistry. ProgrOceangr II: 151-197
Charles CD, Froelich PN, Zibello A, Mortlock RA, Morley
JJ (1991) Biogenic opal in Southern Ocean sediments
over the last 450,000 years: implications for surface
water chemistry and circulation. Paleoceanography
6: 697-728
Dymond J, Suess E, Lyle M (1992) Barium in deep-sea
sediment: A geochemical indicator of
paleoproductivity. Paleoceanography 7: 163-181
Eisenhauer A, Mangini A, Botz R, Walter P, Beer J,
Bonani G, HofinannHJ, Suter M, Wiilfli W (1990) High
resolution lOBe and 230Th stratigraphy of late Quaternary sediments from the Fram Strait (core 23235).
In: Bleil U, Thiede J (eds) Geological history of the
polar oceans: Arctic versus Antarctic. Kluwer,
Dordrecht Boston London, pp 475-487
Francois R, Bacon MP, Suman D (1990) Thorium 230
profiling in deep-sea sediments: High resolution
records of flux and dissolution of carbonate in the
equatorial Atlantic during the last 24,000 years.
Paleoceanography 5: 761-787
Francois R, Bacon MP, Altabet MA, Labeyrie LD (1993)
Glacial/interglacial changes in sediment rain rate
in the SW Indian sector of Subantarctic waters
as recorded by 230Th, 2JlPa, U, and olsN.
Paleoceanography 8: 611-629
Francois R, Bacon MP (1994) Heinrich events in the
North Atlantic: radiochemical evidence. Deep-Sea
Res. 41: 315-334
Francois R, AltabetMA, Yu E-F, Sigman D, Bacon MP,
Frank M, Bohrmann G, Bareille G, Labeyrie L (1997)
Dominance of upper water column stratification in
the southern ocean's contribution to low glacial
atmospheric CO 2 , Nature 389: 929-935
Frank M (1996) Reconstruction oflate Quaternary environmental conditions applying the natural
radionuclides 230Th, lOBe, 231Pa and 238U: A study of
deep-sea sediments from the eastern Atlantic sector of the Antarctic Circumpolar Current system. Ber
Polarforsch Bremerhaven 186, pp 1-136
Frank et al.
rent speed. Higher amounts of focussed sediment
may be caused by a local decrease in current speed,
and consequently decreased capacity of the bottom current to carry particles due to its lower energy. However, it may also point to a larger or more
distant source area in the case of higher current
speed. An unambiguous interpretation ofthe changing redistribution intensity would only be possible
if winnowing had increased, which is a clear indication of higher current speeds. This problem could
be resolved by detailed grain size analyses of all
these cores which are not available at the moment.
In addition, a higher data density is required before
any reliable conclusions may be drawn from such
a map, but nevertheless this preliminary compilation suggests that there is some potential for future
studies.
Acknowledgments
This study was supported by two grants (Ma82 11
9-1; 9-3) of the Deutsche Forschungsgemeinschaft (DFG) to M. F. This research was funded
by the Deutsche F orschungsgemeinschaft (Sonderforschungsbereich 261 at Bremen University,
Contribution No. 176). Data are available under
www.pangaea.de/Projects/SFB261.
References
Abelmann A, Gersonde R (1991) Biosiliceous particle
flux in the Southern Ocean. Mar Chern 35: 503-536
Anderson JB (1990) Sediments. In: Glasby GP (ed)
Antarctic sector of the Pacific. Oceanogr Ser Vol 51 ,
Elsevier, New York, pp 187-205
Anderson RF, Bacon MP, Brewer PG (1983) Removal of
230Th and 2JJPa from the open ocean. Earth Planet Sci
Lett 62: 7-23
Asmus T, Frank M, Koschrnieder C, Frank N, Gersonde
R, Kuhn G, Mangini A (1999) Biogenic particle flux at
the southern Atlantic section of the Subantarctic
Front during the late Quaternary: Evidence from sedimentary 23i Pa and 230Th . Mar Geol, in press
Bacon MP, Rosh~lt IN (1982) Accumulation rates of
DOTh and 231 Pa and some transition metals on the
BermudaRise. Geochim Cosmochim Acta 46: 651-666
Bacon MP (1984) Glacial to interglacial changes in carbonate and clay sedimentation in the Atlantic estimated from thorium-230 measurements. Isot Geosci
2:97-111
Bennekom AJ van, Berger GW, van der Gaast SJ, De
Vries RTP (1988) Primary productivity and the silica
cycle in the in the southern ocean (Atlantic Sector).
Paleogeogr Paleoclimatol Paleoecol67: 19-30
Berger WH, Smetacek V, Wefer G (1989) Productivity of
the ocean: Present and past. In: Berger WH,
Smetacek V and Wefer G (eds) Productivity of the
Ocean: Present and Past. Dahlem Workshop Reports,
J Wiley & Sons, Chichester, pp 1-34
Broecker WS (1982) Glacial to interglacial changes in
ocean chemistry. ProgrOceangr II: 151-197
Charles CD, Froelich PN, Zibello A, Mortlock RA, Morley
JJ (1991) Biogenic opal in Southern Ocean sediments
over the last 450,000 years: implications for surface
water chemistry and circulation. Paleoceanography
6: 697-728
Dymond J, Suess E, Lyle M (1992) Barium in deep-sea
sediment: A geochemical indicator of
paleoproductivity. Paleoceanography 7: 163-181
Eisenhauer A, Mangini A, Botz R, Walter P, Beer J,
Bonani G, HofinannHJ, Suter M, Wiilfli W (1990) High
resolution lOBe and 230Th stratigraphy of late Quaternary sediments from the Fram Strait (core 23235).
In: Bleil U, Thiede J (eds) Geological history of the
polar oceans: Arctic versus Antarctic. Kluwer,
Dordrecht Boston London, pp 475-487
Francois R, Bacon MP, Suman D (1990) Thorium 230
profiling in deep-sea sediments: High resolution
records of flux and dissolution of carbonate in the
equatorial Atlantic during the last 24,000 years.
Paleoceanography 5: 761-787
Francois R, Bacon MP, Altabet MA, Labeyrie LD (1993)
Glacial/interglacial changes in sediment rain rate
in the SW Indian sector of Subantarctic waters
as recorded by 230Th, 2JlPa, U, and olsN.
Paleoceanography 8: 611-629
Francois R, Bacon MP (1994) Heinrich events in the
North Atlantic: radiochemical evidence. Deep-Sea
Res. 41: 315-334
Francois R, AltabetMA, Yu E-F, Sigman D, Bacon MP,
Frank M, Bohrmann G, Bareille G, Labeyrie L (1997)
Dominance of upper water column stratification in
the southern ocean's contribution to low glacial
atmospheric CO 2 , Nature 389: 929-935
Frank M (1996) Reconstruction oflate Quaternary environmental conditions applying the natural
radionuclides 230Th, lOBe, 231Pa and 238U: A study of
deep-sea sediments from the eastern Atlantic sector of the Antarctic Circumpolar Current system. Ber
Polarforsch Bremerhaven 186, pp 1-136