Labrador Sea bottom water provenance and REE exchange during the past 35,000 years
Labrador Sea bottom water provenance and REE exchange during the past 35,000 years
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过去35,000年拉布拉多海底水来源和稀土元素交换
DOI：
10.1016/j.epsl.2020.116299
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发表时间：
2020
影响因子：
5.3
通讯作者：
J. Lippold
中科院分区：
文献类型：
--
作者：
P. Blaser;M. Gutjahr;F. Pöppelmeier;M. Frank;Stefanie Kaboth‐Bahr;J. Lippold
拉布拉多海（LS）深层沃茨是大西洋经向翻转环流的重要贡献者，但其水团结构在不同时间尺度上变化剧烈，对气候变化十分敏感。LS也是海水和下伏沉积物之间稀土元素（REE）交换强烈的区域，这使得基于放射成因钕（Nd）同位素的过去深水物源重建变得复杂。最值得注意的是，西北大西洋底层水交换钕与侏罗纪时代的劳伦特碎屑，导致显着的转变，以减少放射性成因的钕同位素签名之前，它进入北大西洋形成北大西洋深层水的深层部分。研究表明，LS岩心顶部沉积物的自生组分具有介于底层水和碎屑之间的Nd同位素特征，因此反映了孔隙沃茨，它包含了两种特征的混合物。我们还发现，在从哈德逊湾到南极洲的冰川侵蚀物质供应增强时期，孔隙沃茨上的碎屑印记导致自生组分中的REE模式向碎屑特征的转变。LS，由放射性铅同位素记录。这使得过去的底栖稀土交换的强度估计内的LS。我们利用在自生阶段的中间稀土富集的变化，提出一个LS Nd同位素记录的碎屑印记来自孔隙水交换的校正。校正后的钕同位素特征被认为更准确地反映了过去的底层沃茨。这一修正导致MIS 2和MIS 3期间过去LS底层水的特征为−16 ± 1，比今天的放射性低得多。这意味着没有南方来源的沃茨先进的LS在过去的35万年，而是支持连续的底层水来源于北欧海。因此，LS底层沃茨很可能向西北大西洋的北大西洋深海冰川底层水提供了非放射性Nd，正如先前假设的那样。
Deep waters of the Labrador Sea (LS) are important contributors to the Atlantic Meridional Overturning Circulation, but their water mass structure has been highly variable and sensitive to climatic changes on different time scales. The LS is also an area of intense exchange of rare earth elements (REE) between seawater and the underlying sediments, which complicates the reconstruction of past deep water provenance based on radiogenic neodymium (Nd) isotopes. Most notably, Northwest Atlantic Bottom Water exchanges Nd with Archaean age Laurentian detritus, resulting in a significant shift to less radiogenic Nd isotope signatures before it enters the North Atlantic to form the deep part of North Atlantic Deep Water. Here we show that the authigenic fractions of LS core top sediments carry Nd isotope signatures intermediate between bottom water and detritus and thus reflect pore waters that incorporate a mixture of both signatures.We furthermore find that detrital imprints on pore waters led to shifts of REE patterns in the authigenic fraction towards detrital signatures in the past during times of enhanced supply of glacially eroded material from Hudson Bay to the LS, as recorded by radiogenic lead isotopes. This allows an estimation of the intensity of past benthic REE exchange inside the LS.We exploit variations in the mid REE enrichment in the authigenic phase to propose a correction to one LS Nd isotope record for detrital imprints originating from pore water exchange. The correctedϵNd signatures are argued to more accurately reflect those of past bottom waters. This correction results in past LS bottom water signatures of −16 ± 1 during MIS 2 and 3, considerably less radiogenic than today. This implies that no southern sourced waters advanced into the LS during the last 35 ka and instead supports continuous bottom water sourcing from the Nordic Seas. It thus seems likely that LS bottom waters supplied unradiogenic Nd to abyssal Glacial North Atlantic Bottom Water in the Northwest Atlantic, as was previously hypothesized.
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影响因子：
5
作者：
Xin-Yuan Zheng;Y. Plancherel;M. Saito;Peter Scott;G. Henderson
通讯作者：
Xin-Yuan Zheng;Y. Plancherel;M. Saito;Peter Scott;G. Henderson
影响因子：
5
作者：
M. Lambelet;T. Flierdt;K. Crocket;M. Rehkämper;K. Kreissig;B. Coles;M. Rijkenberg;L. Gerringa
通讯作者：
M. Lambelet;T. Flierdt;K. Crocket;M. Rehkämper;K. Kreissig;B. Coles;M. Rijkenberg;L. Gerringa
自末次盛冰期以来大西洋西北深海水团的起源
影响因子：
3.5
作者：
Pöppelmeier;M. Gutjahr;P. Blaser;L. D. Keigwin;J. Lippold
通讯作者：
J. Lippold
影响因子：
5.3
作者：
F. Kurzweil;M. Gutjahr;D. Vance;L. Keigwin
通讯作者：
F. Kurzweil;M. Gutjahr;D. Vance;L. Keigwin
影响因子：
5.3
作者：
Channell, J. E. T.;Hodell, D. A.;Roehl, U.
通讯作者：
Roehl, U.