Aguas Emendadas Research Articles

A dry climatic event during the late Quaternary of tropical Brazil

Two >25,000-yr palynological records from central Brazil (Vereda de Aguas Emendadas, 15°34′S, 47°35′W, and Cromínia, 17°17′S, 49°25′W) start with abundant pollen, spores and algae from cerrado and forest vegetation. A relatively humid and warm climate occurred from >32.4 to ca. 32 ka B.P., and was followed by a very cold and humid climate between 30 and 26 ka B.P. This humid phase was followed by a phase drier than at present between ca. 19 and ca. 7 ka B.P. During that long time there was desertification on the summit of Aguas Emendadas plateau and the disappearance of the palm swamp in Cromínia. After 7 ka B.P., swamp and marsh vegetation started slowly to grow in the sites, indicating humidity was increasing. However, only after ca. 5 ka B.P. did savanna and wet soil vegetations reach the present values. Geological and geomorphological studies from other sites in tropical Brazil support the interpretation of this dry event. A 6200-yr palynological record from the sediments of Lagoa Santa (19°38′S, 43°54′W) shows that the lake started to form at ca. 4.6 ka B.P. after a period of torrential rainfalls. Palynological indication of dryness in South American savannas during the end of the Pleistocene/beginning of the Holocene was also found by other authors. However, records from rain forest areas and the Gran Sabana do not show a marked decrease in moisture suggesting the dry climatic event of Lake Valencia and central Brazil is perhaps limited to ‘cerrado’ areas and plateau summits in lowland regions. These records suggest that the present savanna areas were under severe water stress from ca. 19 to 6-5 ka B.P., and that this event is independent of the glacial meltwater made available by the global water circulation during deglaciation.

Late quaternary palaeoclimate in the savannas of South America

The paper reviews Late Quaternary palynological evidence from eight sites in the savannas of northern South America. The sites reviewed are Lake Valencia (10°N), Carajas (6°S), Aguas Emendadas (15°S), Crominia (17°S), Salitre (19°S), Lagoa de Serra Negra (18°S), Lagoa Santa (20°S) and Lagoa dos Olhos (20°S). Four of the sites show evidence for a climate more humid than at present from ca. 36 ka BP to ca. 22–18 ka BP. Maximum dryness was reached at 14 ka to 10.5 ka BP at Lake Valencia. There was an increase in moisture from 8.8 ka BP at Lake Valencia and from 7 ka BP in Central Brazil. The presence of charcoal indicates human impact from ca. 8.6 ka BP. ©1997 John Wiley & Sons, Ltd.

Late quaternary palaeoclimate in the savannas of South America

The paper reviews Late Quaternary palynological evidence from eight sites in the savannas of northern South America. The sites reviewed are Lake Valencia (10°N), Carajas (6°S), Aguas Emendadas (15°S), Crominia (17°S), Salitre (19°S), Lagoa de Serra Negra (18°S), Lagoa Santa (20°S) and Lagoa dos Olhos (20°S). Four of the sites show evidence for a climate more humid than at present from ca. 36 ka BP to ca. 22–18 ka BP. Maximum dryness was reached at 14 ka to 10.5 ka BP at Lake Valencia. There was an increase in moisture from 8.8 ka BP at Lake Valencia and from 7 ka BP in Central Brazil. The presence of charcoal indicates human impact from ca. 8.6 ka BP. ©1997 John Wiley & Sons, Ltd.