Marine and terrestrial biomarker records for the last 35,000 years at ODP site 658c off NW Africa

• Published in: Organic geochemistry 2000-09, Vol.31 (9), p.919-930
• Main Authors: MEIXUN ZHAO, EGLINTON, Geoffrey, HASLETT, Simon K, JORDAN, Richard W, SARNTHEIN, Michael, ZHAOHUI ZHANG
• Format: Article
• Language: English
• Subjects: Earth sciences; Earth, ocean, space; Exact sciences and technology; Florisphaera profunda; Isotope geochemistry; Isotope geochemistry. Geochronology; Marine and continental quaternary; Radiolaria; Surficial geology
• ISSN: 0146-6380; 1873-5290
• DOI: 10.1016/S0146-6380(00)00027-9

Several high-resolution proxy environmental records have been obtained for the last 35 kyr from ODP Hole 658C, a well-studied site ca. 200 km off Cap Blanc, NW Africa. The collective assessment based on the marine proxies (U sub(37) super(K') SST, contents of TOC and chlorins, Upwelling Radiolarian Index and the percentage of Florisphaera profunda), surprisingly indicates that the last glacial maximum (LGM) was characterized by warmer sea surface temperature (SST), weaker upwelling, and lower marine productivity, compared with the preceding older glacial and subsequent deglaciation periods. Of the terrigenous proxies, the mean grain size of the non-carbonate fraction and the terrigenous alkane content indicate that wind strength and aridity were high. The weaker upwelling at the 658 site during the LGM may have resulted from changes in the strength and direction of the wind systems and/or shifts in the position and geometry of the upwelling cell.