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Climatic changes along the northwestern African Continental Margin over the last 30 kyrs
Author(s) -
Ternois Yann,
Sicre MarieAlexandrine,
Paterne Martine
Publication year - 2000
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/1999gl002306
Subject(s) - alkenone , deglaciation , upwelling , last glacial maximum , geology , glacial period , quaternary , holocene , oceanography , arid , continental margin , climatology , physical geography , geomorphology , paleontology , geography , tectonics
Two sediment cores were investigated to study the regional climatic variability of the NW African upwelling over the late Quaternary. Biomarker data and Sea Surface Temperatures (SSTs) predicted from alkenones at 25°N and 21°N exhibited distinct features. The amplitude of the last deglaciation was estimated to 4.5°C at 25°N and 2–2.5°C at 21°N. At 25°N, terrestrial and marine glacial inputs were higher than Holocene ones as a result of a strengthening of the trade winds and intensification of oceanic production. In contrast, at 21°N, warmer SSTs and lower organic carbon and alkenone productions during the last glacial suggest a regression of the upwelling and therefore a change of wind regime. Low glacial n ‐alkanols are consistent with the migration of the vegetation belt during the maximum of African aridity, while their decrease towards the core‐top may be indicative of anthropogenic disturbances.