globalchange  > 过去全球变化的重建
DOI: 10.1016/j.palaeo.2014.05.030
论文题名:
The role of North Brazil Current transport in the paleoclimate of the Brazilian Nordeste margin and paleoceanography of the western tropical Atlantic during the late Quaternary
作者: Nace T.E.; Baker P.A.; Dwyer G.S.; Silva C.G.; Rigsby C.A.; Burns S.J.; Giosan L.; Otto-Bliesner B.; Liu Z.; Zhu J.
刊名: Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN: 0031-0182
出版年: 2014
卷: 415
起始页码: 3
结束页码: 13
语种: 英语
英文关键词: Amazon margin ; Heinrich events ; Late Quaternary ; North Brazil Current
英文摘要: Reconstructions of surface paleoceanographic conditions of the western equatorial Atlantic and past climates of the adjacent Northeast Brazilian (the "Nordeste") continental margin were undertaken by analyzing sediments from a piston core and associated gravity and box cores recovered from 3107 meter water depth at 0° 20' N on the equatorial Brazilian continental slope. The record is dated by radiocarbon analysis and oxygen isotopic stratigraphy of planktonic foraminifers and spans from near-modern to approximately 110 Ka.High-resolution XRF analysis provides insight into the paleoclimate history of the Nordeste during the last glacial interval. Several large-amplitude and abrupt peaks are observed in the time series of Ti/Ca and are usually accompanied by peaks of Fe/K. Together these record periods of increased precipitation and intense weathering on the adjacent continent and increased terrestrial sediment discharge from Nordeste rivers into the Atlantic. Within the limits of dating accuracy, most Ti/Ca peaks correlate with Heinrich events in the North Atlantic. This record thus corroborates, and extends back in time, the previous record of Arz et al. (1998) determined on sediment cores from farther southeast along the Nordeste margin.Stable oxygen isotopic analysis and Mg/Ca paleothermometry on the near-surface-dwelling planktonic foraminiferal species Globierinoides ruber find that mean sea-surface temperature (SST) during glacial time (20-55 Ka, n. =. 97) was 23.89. ±. 0.79. °C and the mean SST during the late Holocene (0-5 Ka, n. =. 14) was 26.89. ±. 0.33. °C. SSTs were 0.5-2. °C higher and inferred sea-surface salinities were lower during most of the periods of elevated Ti/Ca, thus, as observed in previous studies, the western equatorial Atlantic was warm (at least locally) and the adjacent southern tropical continent was wet at the same time that the high-latitude North Atlantic was cold.Using the SYNTRACE-CCSM3 fully coupled climate model with transient forcing for the period 22 Ka to present, we find that decreased transport of the North Brazil Current co-occurs with reduced Atlantic meridional overturning circulation, and colder-than-normal SSTs in the North Atlantic region. These simulated conditions are invariably associated with significantly increased precipitation in the Nordeste region. © 2014 Elsevier B.V. All rights reserved.
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/69172
Appears in Collections:过去全球变化的重建

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作者单位: Division of Earth and Ocean Sciences, Duke University, Durham, NC, United States; Departamento de Geologia, Universidade Federal Fluminense, Niterói, RJ, Brazil; Department of Geological Sciences, East Carolina University, Greenville, NC, United States; Department of Geosciences, University of Massachusetts, Amherst, MA, United States; Woods Hole Oceanographic Institution, Woods Hole, MA, United States; Climate and Global Dynamics, National Center for Atmospheric Research, Boulder, CO, United States; Department of Atmospheric and Oceanic Sciences, University of Wisconsin, Madison, WI, United States

Recommended Citation:
Nace T.E.,Baker P.A.,Dwyer G.S.,et al. The role of North Brazil Current transport in the paleoclimate of the Brazilian Nordeste margin and paleoceanography of the western tropical Atlantic during the late Quaternary[J]. Palaeogeography, Palaeoclimatology, Palaeoecology,2014-01-01,415
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