Dynamic intermediate ocean circulation in the North Atlantic during Heinrich Stadial 1: A radiocarbon and neodymium isotope perspective

被引:39
作者
Wilson, David J. [1 ]
Crocket, Kirsty C. [1 ,2 ]
van de Flierdt, Tina [1 ]
Robinson, Laura F. [3 ,4 ]
Adkins, Jess F. [5 ]
机构
[1] Univ London Imperial Coll Sci Technol & Med, Dept Earth Sci & Engn, London, England
[2] Scottish Assoc Marine Sci, Scottish Marine Inst, Oban, Argyll, Scotland
[3] Univ Bristol, Sch Earth Sci, Bristol, Avon, England
[4] Woods Hole Oceanog Inst, Dept Marine Chem & Geochem, Woods Hole, MA 02543 USA
[5] CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA
来源
PALEOCEANOGRAPHY | 2014年 / 29卷 / 11期
基金
欧洲研究理事会; 英国自然环境研究理事会;
关键词
Heinrich stadial; deglaciation; Atlantic meridional overturning circulation; neodymium isotopes; radiocarbon; deep sea corals; DEEP-WATER TEMPERATURE; SOUTHERN-OCEAN; THERMOHALINE CIRCULATION; NORDIC SEAS; OVERTURNING CIRCULATION; MERIDIONAL CIRCULATION; LAST DEGLACIATION; MASS GEOMETRY; ND; CLIMATE;
D O I
10.1002/2014PA002674
中图分类号
P [天文学、地球科学];
学科分类号
07 ;
摘要
The last deglaciation was characterized by a series of millennial-scale climate events that have been linked to deep ocean variability. While often implied in interpretations, few direct constraints exist on circulation changes at mid-depths. Here we provide new constraints on the variability of deglacial mid-depth circulation using combined radiocarbon and neodymium isotopes in 24 North Atlantic deep-sea corals. Their aragonite skeletons have been dated by uranium-series, providing absolute ages and the resolution to record centennial-scale changes, while transects spanning the lifetime of a single coral allow subcentennial tracer reconstruction. Our results reveal that rapid fluctuations of water mass sourcing and radiocarbon affected the mid-depth water column (1.7-2.5km) on timescales of less than 100years during the latter half of Heinrich Stadial 1. The neodymium isotopic variability (-14.5 to -11.0) ranges from the composition of the modern northern-sourced waters towards more radiogenic compositions, suggesting the presence of a greater southern-sourced component at some times. However, in detail, simple two-component mixing between well-ventilated northern-sourced and radiocarbon-depleted southern-sourced water masses cannot explain all our data. Instead, corals from similar to 15.0ka and similar to 15.8ka may record variability between southern-sourced intermediate waters and radiocarbon-depleted northern-sourced waters, unless there was a major shift in the neodymium isotopic composition of the northern end-member. In order to explain the rapid shift towards the most depleted radiocarbon values at similar to 15.4ka, we suggest a different mixing scenario involving either radiocarbon-depleted deep water from the Greenland-Iceland-Norwegian Seas or a southern-sourced deep water mass. Since these mid-depth changes preceded the Bolling-Allerod warming and were apparently unaccompanied by changes in the deep Atlantic, they may indicate an important role for the intermediate ocean in the early deglacial climate evolution.
引用
收藏
页码:1072 / 1093
页数:22
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