Climatic change during the Younger Dryas chron in northern South America a test of the evidence
New AMS and palynological data are presented from the Colombian Andes to assess vegetational and climatic change during the Lateglacial-Holocene transition, with special emphasis on the Younger Dryas (YD) chronozone. The new evidence is compared and discussed with other Colombian cores and with data from other countries in the region. The Lateglacial climatic reversal in Colombia, known as the El Abra stadial, has an estimated lower boundary of 11,200 (conventional) and 10,900 (interpolated) 14C yr BP, respectively. Although the El Abra stadial is assumed to be the equivalent of the European YD, the present data suggest that the El Abra stadial is a biostratigraphical signal representing both the YD chronozone and the earliest Holocene (11,000-9000 14C yr BP). On the basis of new AMS dates and a re-evaluation of the pollen zones, we divided the Colombian El Abra biozone into two phases. From ca. 11,000 to ca. 10,500 14C yr BP there is a sharp increase of subparamo and paramo pollen, reflecting a relatively cool phase during the YD chronozone (zone Y1). After ca. 10,500 14C yr BP, a slight increase of arboreal pollen and the presence of Cactaceae (zone Z1) point toward a relatively milder but drier phase extending to ca. 9000 14C yr BP in the earliest Holocene.
| Main Authors: | , , |
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| Format: | Texto biblioteca |
| Language: | eng |
| Subjects: | Palinología, Cambio climático, |
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