Composition and circulation of bottom water in the western Atlantic Ocean during the last glacial, based on pore-water analyses from the Amazon Fan

Pore waters from very rapidly deposited continental margin sediments may provide a record of changes in the isotopic and chemical composition of seawater over time. Measurements made on pore waters extracted from sediments drilled at five sites during Ocean Drilling Program Leg 155 on the Amazon Fan...

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Bibliographic Details
Main Authors: Burns, SJ, Maslin, MA
Format: Article in Journal/Newspaper
Language:unknown
Published: GEOLOGICAL SOC AMERICA, INC 1999
Subjects:
NORTH-ATLANTIC
DEEP-OCEAN
TEMPERATURE
SEDIMENTATION
CYCLES
RATES
Antarctic
Antarc*
North Atlantic Deep Water
North Atlantic
Online Access:http://discovery.ucl.ac.uk/101364/
Description
Summary:Pore waters from very rapidly deposited continental margin sediments may provide a record of changes in the isotopic and chemical composition of seawater over time. Measurements made on pore waters extracted from sediments drilled at five sites during Ocean Drilling Program Leg 155 on the Amazon Fan show systematic increases in delta(18)O with depth from similar to 0.1 parts per thousand in surface sediments to similar to 0.4 parts per thousand in glacial-age sediments from below about 40 m below sea floor. This relatively small glacial-interglacial difference reflects both the overall increase in delta(18)O of seawater during the last glacial and a change in bottom-water source to the area from North Atlantic Deep Water at present to relatively O-18 depleted Antarctic Bottom Water during the last glacial. When combined with delta(18)O analyses of benthic foraminifers, the pore-water data indicate a glacial-interglatial temperature change of about 4 degrees C.

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