Neodymium Evidence for Increased Circumpolar Deep Water Flow to the North Pacific During the Middle Miocene Climate Transition
Neodymium Evidence for Increased Circumpolar Deep Water Flow to the North Pacific During the Middle Miocene Climate Transition
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DOI：
10.1029/2017pa003309
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发表时间：
2018-07
影响因子：
3.5
通讯作者：
S. Kender;K. Bogus;T. Cobb;D. J. Thomas
中科院分区：
文献类型：
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作者：
S. Kender;K. Bogus;T. Cobb;D. J. Thomas
低盐度地表水抑制现代北太平洋局部深水形成。相反，来自南方的环极深水（CDW）填充了盆地，这是南大洋和北大西洋冷沉降中心形成的水团的产物。这个CDW负责在太平洋深处输送大量的全球热量和溶解碳。它的流动历史和更广泛的翻转环流被广泛认为对气候扰动很敏感。然而，缺乏足够的记录存在于北太平洋深部的CDW存在，以评估其演变和在过去23 Ma的主要气候转变中的作用。在这里，我们报告沉积涂层和鱼齿钕同位素值-水团混合的示踪剂-来自深水国际海洋发现计划U1438站点（水深4.7 km），菲律宾海，西北太平洋。我们的研究结果表明，水团转移从北太平洋源在中新世早期的南部来源约14 Ma。在年龄模型和时间的限制，这一重大的重组北太平洋水团结构可能与冰盖建立在南极洲，是最一致的增加向北流动的CDW由于加强下沉的冷水被迫南极冷却。在过去14 Ma的大部分时间里，这种通量的北向范围可能保持相对恒定。
Low salinity surface water inhibits local deepwater formation in the modern North Pacific. Instead, southern‐sourced Circumpolar Deep Water (CDW) fills the basin, which is the product of water masses formed from cold sinking centers in the Southern Ocean and North Atlantic. This CDW is responsible for transporting a significant amount of global heat and dissolved carbon in the deep Pacific Ocean. The history of its flow and the broader overturning circulation are widely assumed to be sensitive to climate perturbations. However, insufficient records exist of CDW presence in the deep North Pacific with which to evaluate its evolution and role in major climate transitions of the past 23 Ma. Here we report sedimentary coatings and fish teeth neodymium isotope values—tracers for water‐mass mixing—from deepwater International Ocean Discovery Program Site U1438 (4.7 km water depth) in the Philippine Sea, northwest Pacific Ocean. Our results indicate the water mass shifted from a North Pacific source in the early Miocene to a southern source by ~14 Ma. Within the age model and temporal constraints, this major reorganization of North Pacific water mass structure may have coincided with ice sheet build up on Antarctica and is most consistent with an increased northward flux of CDW due to enhanced sinking of cold water forced by Antarctic cooling. The northward extent of this flux may have remained relatively constant during much of the past 14 Ma.