Abstract. The Paleogene history of biogenic opal accumulation in the North Atlantic provides insight into both the evolution of deep-water circulation in the Atlantic basin, and weathering responses to major climate shifts. However, existing records are compromised by low temporal resolution and/or stratigraphic discontinuities. In order to address this problem, we present a multi-site, high-resolution record of biogenic silica (_bioSiO₂) accumulation from Blake Nose (ODP Leg 171B, western North Atlantic) spanning the early Paleocene through late Eocene time interval (~65‒34 Ma). This record represents the longest single-locality history of marine _bioSiO₂ burial compiled to date and offers a unique perspective into changes in _bioSiO₂ fluxes through the early-to-mid Paleogene extreme greenhouse interval and subsequent period of long-term cooling. Blake Nose _bioSiO₂ fluxes display prominent fluctuations that we attribute to variations in sub-thermocline nutrient supply via cyclonic eddies associated with the Gulf Stream. Whereas few constraints are available on the _bioSiO₂ flux pulses peaking in the early Paleocene and early Eocene, a middle Eocene interval of elevated _bioSiO₂ flux between ~46 and 42 Ma is proposed to reflect nutrient enrichment due to invigorated overturning circulation following an early onset of Northern Component Water export from the Norwegian-Greenland Sea at ~49 Ma. Comparison of our North Atlantic record against published Pacific _bioSiO₂ flux records indicates a diminished nutrient supply to the Atlantic between ~42 and 38 Ma, interpreted as a response to weakening of the overturning circulation. Subsequently, a deep-water circulation regime favoring limited _bioSiO₂ burial in Atlantic and enhanced _bioSiO₂ burial in the Pacific was established after ~38 Ma, likely in association with a further invigoration of deep-water export from the North Atlantic. We also observe that Blake Nose _bioSiO₂ fluxes through the middle Eocene cooling interval (~48 to 34 Ma) are consistently higher than background fluxes throughout the late Paleocene‒early Eocene interval of intense greenhouse warmth. This observation is consistent with a temporally variable rather than constant silicate weathering feedback strength model for the Paleogene, which would instead predict that marine _bioSiO₂ burial should peak during periods of extreme warming.

中文翻译：

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北大西洋海洋生物硅在古近纪中期到中期的积累：对海洋环流和硅酸盐风化反馈的影响

摘要。北大西洋生物蛋白石积累的古近纪历史为了解大西洋盆地深水循环的演变以及对主要气候变化的风化响应提供了见识。然而，现有的记录受到低时间分辨率和/或地层不连续性的损害。为了解决这个问题，我们提出了一个多站点，生物硅的高分辨率记录（_生物的SiO ₂从布莱克鼻（ODP腿171B，北大西洋西部）横跨古新世早期）的积累，通过晚始新世的时间间隔（〜 65‒34 Ma）。该记录代表了海洋_生物SiO ₂最长的单地点历史迄今已完成的墓葬研究，为古生代早期至中期极端温室间隔以及随后的长期降温期间_生物SiO ₂流量的变化提供了独特的视角。Blake Nose的_生物SiO ₂通量显示出显着的波动，这归因于与湾流相关的旋风涡旋引起的亚热跃层养分供应的变化。而几个约束对可_生物的SiO _2个通量脉冲在早期古和早期始新世，峰值升高的中间始新世间隔_生物的SiO ₂建议在约46Ma至42Ma之间通量，以反映由于挪威-格陵兰海北部地区约49Ma的北部成分水出口较早开始而引起的翻覆循环加剧而引起的养分富集。将我们的北大西洋记录与已公布的太平洋_生物SiO ₂通量记录进行比较，表明在〜42至38 Ma之间对大西洋的营养供应减少了，这被解释为对倾覆环流减弱的反应。随后，深水循环机制有利于限制大西洋中有限的_生物SiO ₂埋藏并增强_生物SiO ₂大约38 Ma之后在太平洋建立了埋葬地，这可能与北大西洋深水出口的进一步活跃有关。我们还观察到，在强烈的温室暖化的古新世-始新世晚期，整个始新世中期冷却间隔（约48至34 Ma）的Blake Nose_生物SiO ₂通量始终高于本底通量。该观察结果与古近代的时间变量而不是恒定的硅酸盐风化反馈强度模型一致，该模型将预测海洋_生物SiO ₂埋藏应在极端变暖时期达到峰值。