M. Maslin,2,3 S. Burns,4 H. Erlenkeuser,5 and C. Hohnemann2


The Amazon Fan is an excellent area to obtain the climatic records of the last glacial-interglacial cycle. Glacial sedimentation rates ranging from 1 m to over 50 m/k.y. provide an opportunity to obtain marine records approaching the resolution of the Greenland ice cores. Ocean Drilling Program (ODP) Leg 155 Sites 932 and 933 from the eastern, mid-Amazon Fan complex have been studied initially at a resolution of 50 cm (100-400 yr per sample). The identification of paleomagnetic excursions, distinctive patterns in the paleomagnetic remanence intensity records, and radiocarbon dates have provided an age framework for both Sites 932 and 933. However, it was only possible to construct a detailed age model for Site 932. Planktonic foraminiferal stable oxygen and carbon isotope records of six species were obtained for both sites.

The planktonic foraminiferal carbon isotope records of both Sites 932 and 933 show a distinct negative deviation during Termination I (13-15 calendar ka). We suggest this could have been caused by an increase in the sediment discharge of the Amazon River because of the deglaciation of the Andes and/or the release of significant quantities of gas hydrates as large parts of the Amazon Fan sediment column fail because of increased sea level. Positive deviations occur in the composite Site 932 oxygen isotope record, the timing of which seems to coincide with the Heinrich events of the high latitude North Atlantic. However, there are considerable doubts over the validity of the composite record, the Site 932 age model, and the possible affects of reworking.

1Flood, R.D., Piper, D.J.W., Klaus, A., and Peterson, L.C. (Eds.), 1997. Proc. ODP, Sci. Results, 155: College Station, TX (Ocean Drilling Program).
2Geologisch-Paläontologisches Institut, Universität Kiel, Olshausenstrasse 40, 24098 Kiel, Federal Republic of Germany.
3Current address: Environmental Change Research Centre, Department of Geography, University College London, 26 Bedford Way, London WC1H 0AP, United Kingdom. MMaslin@geog.ucl.ac.uk
4Geologisches Institut, Universität Bern, Baltzerstrasse 1, CH-3012, Bern, Switzerland.
5C-14 Laboratory, Department of Physics, Universität Kiel, 24098 Kiel, Federal Republic of Germany.