DOI: 10.5194/cp-12-623-2016
Scopus记录号: 2-s2.0-84960957594
论文题名: Variability in terrigenous sediment supply offshore of the Río de la Plata (Uruguay) recording the continental climatic history over the past 1200 years
作者: Perez L. ; García-Rodríguez F. ; Hanebuth T.J.J.
刊名: Climate of the Past
ISSN: 18149324
出版年: 2016
卷: 12, 期: 3 起始页码: 623
结束页码: 634
语种: 英语
Scopus关键词: Atlantic Multidecadal Oscillation
; climate forcing
; continental shelf
; diatom
; freshwater sediment
; Little Ice Age
; marine environment
; Medieval Warm Period
; rainfall
; relative abundance
; river plume
; sediment core
; sediment transport
; sedimentation rate
; terrigenous deposit
; water depth
; Atlantic Ocean
; Atlantic Ocean (South)
; Rio de la Plata
; Uruguay
; Bacillariophyta
英文摘要: The continental shelf adjacent to the Río de la Plata (RdlP) exhibits extremely complex hydrographic and ecological characteristics which are of great socioeconomic importance. Since the long-term environmental variations related to the atmospheric (wind fields), hydrologic (freshwater plume), and oceanographic (currents and fronts) regimes are little known, the aim of this study is to reconstruct the changes in the terrigenous input into the inner continental shelf during the late Holocene period (associated with the RdlP sediment discharge) and to unravel the climatic forcing mechanisms behind them. To achieve this, we retrieved a 10 m long sediment core from the RdlP mud depocenter at 57 m water depth (GeoB 13813-4). The radiocarbon age control indicated an extremely high sedimentation rate of 0.8 cm per year, encompassing the past 1200 years (AD 750-2000). We used element ratios (Ti/Ca, Fe/Ca, Ti/Al, Fe/K) as regional proxies for the fluvial input signal and the variations in relative abundance of salinity-indicative diatom groups (freshwater versus marine-brackish) to assess the variability in terrigenous freshwater and sediment discharges. Ti/Ca, Fe/Ca, Ti/Al, Fe/K and the freshwater diatom group showed the lowest values between AD 850 and 1300, while the highest values occurred between AD 1300 and 1850. The variations in the sedimentary record can be attributed to the Medieval Climatic Anomaly (MCA) and the Little Ice Age (LIA), both of which had a significant impact on rainfall and wind patterns over the region. During the MCA, a weakening of the South American summer monsoon system (SAMS) and the South Atlantic Convergence Zone (SACZ), could explain the lowest element ratios (indicative of a lower terrigenous input) and a marine-dominated diatom record, both indicative of a reduced RdlP freshwater plume. In contrast, during the LIA, a strengthening of SAMS and SACZ may have led to an expansion of the RdlP river plume to the far north, as indicated by higher element ratios and a marked freshwater diatom signal. Furthermore, a possible multidecadal oscillation probably associated with Atlantic Multidecadal Oscillation (AMO) since AD 1300 reflects the variability in both the SAMS and SACZ systems. © 2016 Author(s). Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/49046
Appears in Collections: 气候变化与战略
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Recommended Citation:
Perez L.,García-Rodríguez F.,Hanebuth T.J.J.. Variability in terrigenous sediment supply offshore of the Río de la Plata (Uruguay) recording the continental climatic history over the past 1200 years[J]. Climate of the Past,2016-01-01,12(3)