In:
The Holocene, SAGE Publications, Vol. 15, No. 4 ( 2005-05), p. 625-630
Abstract:
From west to east, the Fluminense coastline, composed of two series of lagoons, presents an aridity gradient induced by a local upwelling that is controlled by trade winds coming from the south Atlantic. The physico-chemical conditions of the lagoons are controlled by the duration of the dry season. They are characterized by hypersaline conditions with organic-carbonate sedimentation in the upwelling-influenced area, and by hyposaline conditions with organic-detrital sedimentation out of the upwelling-influenced area. On a core collected in the Brejo do Espinho hypersaline lagoon, diatom analysis supported by sedimentological data revealed a varying high water level from 4500 to 2200 14 C yr BP induced by successive freshwater inputs in to the lagoon. Two major dry events occurred during this period, probably related to relative sea-level fluctuations. At 2200 14 C yr BP, a drastic change occurred, as indicated by a carbonate nodule, carbonate-dominated sediments and polyto hypersaline diatoms, all suggesting arid conditions. The Brejo do Espinho record suggests that before 2200 14 C yr BP, the central part of the Brazilian coast was mostly subjected to south to southeasterly winds and weaker trade winds, whereas after 2200 14 C yr BP, trade winds dominated, implying drier conditions at the easternmost part of the Fluminense coastline. These results would also suggest a late Holocene increase in El Ninlo activity (after 2200 14 C yr BP), consistent with several El Nifio records from western South America.
Type of Medium:
Online Resource
ISSN:
0959-6836
,
1477-0911
DOI:
10.1191/0959683605hl823rr
Language:
English
Publisher:
SAGE Publications
Publication Date:
2005
detail.hit.zdb_id:
2027956-5
SSG:
14
SSG:
3,4
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