Millennial climatic variability during MIS 2 and 3 in the Western Mediterranean Sea: the coccolithophore record
Abstract
A detailed quantitative analysis of coccolithophore assemblages has been carried out in the upper half of the IMAGES core MD99-2343 (41º29.84’N, 4º01.69’E, 2391 m) This core was recovered at the NE margin of the Catalonian-Balearic Sea (W Mediterranean). The superficial hydrodynamic pattern of this basin is characterised by the southwestward flow of cold waters along the Spanish slope and the northward flow of modified atlantic water masses through the Balearic archipelago. The age model of core MD99-2343 was performed by the correlation of its G. bulloides oxygen isotopic curve with the GRIP ice core isotopic curve. The upper 1730 cm of core MD99-2343 cover the last 50 kyrs, with an averaged sedimentation rate of about 34 cm/kyr. The composition of the coccolithophore assemblage recorded in core MD99-2343 is similar to those reported in previous studies carried out in the Western Mediterranean. Gephyrocapsids and Emiliania huxleyi are the dominant taxa; other species such as Calcidiscus leptoporus, Helicosphaera carteri and Syracosphaera spp. occur in smaller proportions. A high-resolution analysis shows millennial scale variations in the response of most of the taxa. These changes can be correlated to the Heinrich and Dansgaard-Oeschger cyclicity identified in the isotopic record. Possible changes in SST and in the water column structure are evidenced by the succession of warm/oligotrophic and cold water taxa at the DO Interstadials and Stadials/Heinrich Events, respectively. Coccolith absolute abundances are also higher during Interstadials; however, dilution due to higher terrigenous input during cold events cannot be discarded. Increases of other taxa (H. carteri and Syracosphaera spp.) are also synchronous with these cold events. All these facts can be indicating lower coccolithophore production and low SST, coincident with an enhancement of the flow of colder waters during Heinrich Events and Dansgaard-Oeschger Stadials to the area.
- Publication:
-
EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003
- Bibcode:
- 2003EAEJA.....5413C