Sediment composition and stable isotopic ratio of Neogloboquadrina pachyderma from DSDP Site 94-609_Site, North Altlantic

Digitized records of optical desnity in many North Atlantic cores exihibt rapid changes from lighter to darker extrems, typically within less than 200 years, at the 5d/5e, 5b/5c and 4/5 boundaries. In cores from DSDP site 609 the changes from lighter to darker color coincide with increasing in relat...

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Bibliographic Details
Main Authors: Bond, Gerard C, Broecker, Wallace S, Lotti, Rusty, McManus, Jerry F
Format: Other/Unknown Material
Language:English
Published: PANGAEA 1992
Subjects:
94-609_Site
COMPCORE
Composite Core
Deep Sea Drilling Project
DSDP
Glomar Challenger
Leg94
North Atlantic/FLANK
Neogloboquadrina pachyderma
North Atlantic
Online Access:https://doi.pangaea.de/10.1594/PANGAEA.667181
https://doi.org/10.1594/PANGAEA.667181
Description
Summary:Digitized records of optical desnity in many North Atlantic cores exihibt rapid changes from lighter to darker extrems, typically within less than 200 years, at the 5d/5e, 5b/5c and 4/5 boundaries. In cores from DSDP site 609 the changes from lighter to darker color coincide with increasing in relative abundance of Neogloboquadrina pachyderma (l.c.), with increases in abundances of lithic grains and with decreasing in carbonate content. The rapid changes to dark color, therefore, are climate-driven and correspond to a lowering of seas surface temperatures and to increases in amounts of ice rafted debris relative to biogenic carbonate. At the 5d&4c boundary, delta18O in N. pachyderma (l.c.) increases abruptly with the change to darker sediments as expected for cooler sea surface temperatures. At the 4/5 boundary, however, delta18O decreases with the change to darker sediment and cooler sea surface temperatures, suggesting that a layer of fresh surface water was present in the North Atlantic at that time.

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