DOI: 10.5194/cp-8-415-2012
Scopus记录号: 2-s2.0-84858837927
论文题名: Climatically-controlled siliceous productivity in the eastern Gulf of Guinea during the last 40 000 yr
作者: Crosta X. ; Romero O.E. ; Ther O. ; Schneider R.R.
刊名: Climate of the Past
ISSN: 18149324
出版年: 2012
卷: 8, 期: 2 起始页码: 415
结束页码: 431
语种: 英语
Scopus关键词: bioaccumulation
; community structure
; diatom
; Heinrich event
; humid environment
; Last Glacial Maximum
; paleoceanography
; paleoclimate
; paleoenvironment
; precipitation (climatology)
; sea level change
; timescale
; Atlantic Ocean
; Gulf of Guinea
; Bacillariophyta
英文摘要: Opal content and diatom assemblages were analysed in core GeoB4905-4 to reconstruct siliceous productivity changes in the eastern Gulf of Guinea during the last 40 000 yr. Opal and total diatom accumulation rates presented low values over the considered period, except during the Last Glacial Maximum and between 15 000 calendar years Before Present (15 cal. ka BP) and 5.5 cal. ka BP, the so-called African Humid Period, when accumulation rates of brackish and freshwater diatoms at the core site were highest. Conversely, accumulation rates of windblown diatoms exhibited an opposite pattern with higher values before and after the African Humid Period and greatest values during Heinrich Events, the Younger Dryas and since 5.5 cal. ka BP. Our results demonstrate that siliceous productivity in the eastern Gulf of Guinea was directly driven by the nutrient load from local rivers, whose discharges were forced by precipitation changes over western Equatorial Africa and/or modification of the fluvio-deltaic systems forced by sea level changes. Precipitation in this region is controlled by the West African monsoon which is, in turn, partly dependent on the presence and intensity of the Atlantic Cold Tongue (ACT). Our results therefore suggest that the ACT was weakened, warmer trade winds were less vigorous, and cloud convection and precipitation were greater during the AHP though centennial-to-millennial timescale dry events were observed at ∼10 cal. ka BP, ∼8.5 cal. ka BP and ∼6 cal. ka BP. Conversely, the ACT was more intense, trade winds were more vigorous and African climate was more arid during H1, the Younger Dryas and after 5.5 cal. ka BP into the present. © 2012 Author(s). Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/49607
Appears in Collections: 气候变化与战略
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Recommended Citation:
Crosta X.,Romero O.E.,Ther O.,et al. Climatically-controlled siliceous productivity in the eastern Gulf of Guinea during the last 40 000 yr[J]. Climate of the Past,2012-01-01,8(2)