Palaeoreconstruction of the Amazon River freshwater and sediment discharge using sediments recovered at Site 942 on the Amazon Fan
✍ Scribed by M. A. Maslin; E. Durham; S. J. Burns; E. Platzman; P. Grootes; S. E. J. Greig; M-J. Nadeau; Markus Schleicher; U. Pflaumann; B. Lomax; N. Rimington
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 456 KB
- Volume
- 15
- Category
- Article
- ISSN
- 0267-8179
No coin nor oath required. For personal study only.
✦ Synopsis
A continuous reconstruction of palaeoclimate has been generated for the last 12 000 14 C yr BP, from ODP site 942 (5°45′N, 49°6′W at a water depth of 3346 m), drilled to the west of the Amazon Fan. Records from the site suggest that during the Younger Dryas, the Amazon Basin was extremely dry, and Amazon River discharge was low. This increased aridity is hypothesised to be due predominantly to reduced precipitation. In addition, there is evidence for a discharge event at the end of the Younger Dryas, coeval with Termination 1B, that produced an estimated Amazon River outflow equivalent to present-day values, and an increase in sediments derived from the Andes. The timing of this event, coincident with the warming of the Andean Ice Sheet, suggests that it was at least partly driven by meltwater produced by the retreat of Andean glaciers, but also required an increase in regional rainfall resulting from changes in climate. Site 942 also demonstrates that the sediment input to the western part of the Amazon Fan from the river ceased between 9900 and 9500 14 C yr BP, at a time when sea level was 40-50 m below the present level. If this value is truly indicative of the sea levels at which the sediment supply to the fan switched 'off', then it is far greater than the 30 m below current sea-level suggested previously.