Sedimentary organic matter and carbonate variations in the Chukchi Borderland in association with ice sheet and ocean-atmosphere dynamics over the last 155 kyr
Sedimentary organic matter and carbonate variations in the Chukchi Borderland in association with ice sheet and ocean-atmosphere dynamics over the last 155 kyr
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DOI：
10.5194/bg-8-3545-2011
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发表时间：
2011-12
期刊：
影响因子：
4.9
通讯作者：
S. Rella;M. Uchida
中科院分区：
文献类型：
--
作者：
S. Rella;M. Uchida
抽象的。了解北冰洋沉积有机碳过去的变化情况，对于评估与全球气候变化有关的自然碳循环和迁移过程十分重要。然而，对北极晚更新世海洋学历史的了解仍然很少。在目前的研究中，我们显示了沉积记录的总有机碳（TOC），碳酸钙，底栖有孔虫δ 18 O和粗粒度部分从活塞芯回收的北方北风岭在遥远的北冰洋西部，一个地区可能敏感地响应过去的变化，表面电流制度和沉积过程，如海岸侵蚀。基于氧地层学、放射性碳测年和岩性限制的年龄模型表明，活塞岩心记录了过去15.5万年的古环境变化。TOC显示的轨道尺度的增加和减少，可以分别与占主导地位的欧亚北极的大冰盖的变大和变小，这表明平流细悬浮物质来自冰川侵蚀北风岭向东流动的中间水和/或地表水和海冰在寒冷的情节，最后两个冰期-间冰期循环。在千年尺度上，TOC的增加可能与一套120和45万年前（BP）的Dansgaard-Oeschger Stadials，表明可能的响应突然北方半球的温度变化。70和45万年BP之间，封闭和开放的白令海峡可能会影响TOC的变化。CaCO 3含量往往反相关TOC的轨道和千年的时间尺度上，我们解释增强沉积物平流从富含碳酸盐的加拿大北极通过延长博福特环流在温暖的时期，最后两个冰川间冰期循环和增加有机碳平流从西伯利亚北极在寒冷的时期，当博福特环流收缩。我们建议，这种模式可能与轨道和千年尺度的变化，占主导地位的大气表面压力系统表示的模式转变的北极涛动。
Abstract. Knowledge on past variability of sedimentary organic carbon in the Arctic Ocean is important to assess natural carbon cycling and transport processes related to global climate changes. However, the late Pleistocene oceanographic history of the Arctic is still poorly understood. In the present study we show sedimentary records of total organic carbon (TOC), CaCO3, benthic foraminiferal δ18O and the coarse grain size fraction from a piston core recovered from the northern Northwind Ridge in the far western Arctic Ocean, a region potentially sensitively responding to past variability in surface current regimes and sedimentary processes such as coastal erosion. An age model based on oxygen stratigraphy, radiocarbon dating and lithological constraints suggests that the piston core records paleoenvironmental changes of the last 155 kyr. TOC shows orbital-scale increases and decreases that can be respectively correlated to the waxing and waning of large ice sheets dominating the Eurasian Arctic, suggesting advection of fine suspended matter derived from glacial erosion to the Northwind Ridge by eastward flowing intermediate water and/or surface water and sea ice during cold episodes of the last two glacial-interglacial cycles. At millennial scales, increases in TOC might correlate to a suite of Dansgaard-Oeschger Stadials between 120 and 45 ka before present (BP) indicating a possible response to abrupt northern hemispheric temperature changes. Between 70 and 45 ka BP, closures and openings of the Bering Strait could have additionally influenced TOC variability. CaCO3 content tends to anti-correlate with TOC on both orbital and millennial time scales, which we interpret in terms of enhanced sediment advection from the carbonate-rich Canadian Arctic via an extended Beaufort Gyre during warm periods of the last two glacial-interglacial cycles and increased organic carbon advection from the Siberian Arctic during cold periods when the Beaufort Gyre contracted. We propose that this pattern may be related to orbital- and millennial-scale variations of dominant atmospheric surface pressure systems expressed in mode shifts of the Arctic Oscillation.