Variability in mid‐depth ventilation of the western Atlantic Ocean during the last deglaciation-猫眼课题宝

DOI：

10.1002/2017pa003095

发表时间：

2017-09

期刊：

Paleoceanography

影响因子：

通讯作者：

中科院分区：

地学2区

文献类型：

作者：

I. Voigt;A. P. Cruz;S. Mulitza;C. Chiessi;A. Mackensen;J. Lippold;Benny Antz;M. Zabel;Yancheng Zhang;C. Barbosa;A. Tisserand

在海因里希阶梯1(HS1)和年轻仙女木(YD)期间，大西洋中深度(~1000-3000米)的大部分海域都观察到了负的稳定碳同位素漂移。尽管人们一致认为这些中深度漂移在某种程度上与大西洋子午线翻转环流的减缓有关，但对于确切的机制仍没有达成共识(S)。本文介绍了赤道西部大西洋5个岩心的海底稳定碳、氧同位素(δ13C和δ18O)记录。结合已公布的附近岩心的海底同位素记录，我们制作了WEA深度断面(约800-2500米)。我们将这条样带的Hs1和YD数据与之前公布的北大西洋和南大西洋岩心的数据进行了比较，结果表明，在这些时间段，最大的负δ13C漂移发生在西太平洋。此外，我们的海底δ18O记录要求存在两个从南大洋流出的水团，被北方分量水(NCW)一分为二。鉴于δ18O是一种保守的水团示踪剂，我们认为δ13C与水团组成解偶联，并不对应于南北来源水域之间的简单交替。相反，δ13C在HS1和YD期间表现为非保守性。与我们在横断面上的231Pa230次新记录一致，我们假设δ13C的负漂移反映了NCW的停留时间随着AMOC的减弱而增加，从而允许13C耗尽的呼吸碳在WEA中层显著积累。

Negative stable carbon isotopic excursions have been observed throughout most of the mid-depth (~1000–3000 m) Atlantic Ocean during Heinrich Stadial 1 (HS1) and the Younger Dryas (YD). Although there is an agreement that these mid-depth excursions were in some way associated with a slowdown of the Atlantic Meridional Overturning Circulation (AMOC), there is still no consensus on the precise mechanism(s). Here we present benthic stable carbon and oxygen isotopic (δ13C and δ18O) records from five cores from the western equatorial Atlantic (WEA). Together with published benthic isotopic records from nearby cores, we produced a WEA depth transect (~800–2500 m). We compare HS1 and YD data from this transect with data from previously published North and South Atlantic cores and demonstrate that the largest negative δ13C excursions occurred in the WEA during these times. Moreover, our benthic δ18O records require the presence of two water masses flowing from the Southern Ocean, bisected by a Northern Component Water (NCW). Given that δ18O is a conservative water mass tracer, we suggest that δ13C was decoupled from water mass composition and does not correspond to simple alternations between northern and southern sourced waters. Instead, δ13C behaved non-conservatively during HS1 and the YD. Consistently with our new 231Pa/230Th record from the WEA transect, that allowed the reconstruction of AMOC strength, we hypothesize that the negative δ13C excursions reflect an increase in the residence time of NCW in response to a weakened AMOC, allowing for a marked accumulation of 13C-depleted respired carbon at the mid-depth WEA.

Variability in mid‐depth ventilation of the western Atlantic Ocean during the last deglaciation

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