Respuesta de los Cocolitofóridos a los cambios atmosféricos y oceanográficos durante el Periodo Húmedo Africano del Holoceno en el Atlántico
- Autores: A. Mejía Molina
- Localización: Geogaceta, ISSN 0213-683X, Nº. 39, 2005, págs. 99-102
- Idioma: español
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Resumen
Core MD03 2705 was recovered at 18ºN-21ºW at a water depth of 3100 m off Mauritania-Senegal (NW Africa) during the Marion Dufresne II Cruise PICABIA. Qualitative analyses carried out in coccolithophores and wind-transported microfossils from continental NW African areas (phytholiths and fresh-water diatoms), allow us to interpret variations in the direction and intensity of winds and their relationship with surface water dynamics during the Holocene African Humid Period (AHP) (9-5.5 ka). The terrigenous record exhibits a well-defined period of low influx associated with the AHP, when the Sahara was near completely vegetated and covered by perennial lakes. Variations in the production of coccolithophores, showing high productivity during the wet conditions, were monitored. A rapid shift to arid conditions at the end of the AHP coincides with higher abundance in fresh-water diatoms and phytholiths, as well as a positive pulse in the Ti/Al ratio, suggesting intensification in the wind regime. At this time, coccolithophores show a dramatic decreasing of the cool-water species Gephyrocapsa muellerae, interpreted as a return to warmer conditions.
