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Tracking deep-water flow on Eirik Drift over the past 160 kyr: Linking deep-water changes to freshwater fluxes.

机译：跟踪过去160年来在Eirik Drift上的深水流量：将深水变化与淡水通量联系起来。

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摘要

This dissertation uses surface and deep ocean proxies to understand changes in North Atlantic deep-water production associated with periods of increased freshwater input throughout the Late Pleistocene and Holocene. Coring sites on Eirik Drift have long-term sedimentation rates exceeding 15 cm/kyr., allowing for paleoceanographic reconstructions on Milankovitch and millennial time scales.The transition from glacial North Atlantic Intermediate Water (gNAIW) of marine isotope chron (MIC) 2 to North Atlantic Deep Water (NADW) during the Holocene is examined in Chapter 1. Early Holocene (9000-10,500 ka), sedimentation rates in core 21GGC (3471 m) are >100 cm/kyr., indicating gNAIW winnowed upstream glacial sediments, depositing at 21GGC. Enhanced sediment deposition persisted until &sim9ka when long-term rates leveled off at 40 cm/kyr., indicating NADW density had stabilized. From 8.6 to 8.2 ka, catastrophic drainage of glacial Lake Agassiz poured freshwater into the North Atlantic disrupting deep-ocean circulation.Chapter 2 focuses on the past 160 kyr at Site 1306 (2272 m) on the Eirik Drift where highest sedimentation rates occurred during MIC 2- 5d. Mean sortable silt (SS) and delta18O of N. pachyderma (s) are inversely related during this interval, indicating that changes in surface conditions above the Eirik Drift are propagated into the deep ocean. During the past 40 kyr., SS decreases are concomitant with instances of surface ocean freshening. These intervals correlate with Heinrich Events, suggesting that massive ice flows released from the continents altered deep ocean circulation.The final chapter examines deep-ocean response during Terminations 1 and 2. Higher insolation forcing across Termination 2 is postulated to promote rapid melting of continental glaciers, leaving little opportunity for continental storage of freshwater. Conversely, lower insolation across Termination 1 allowed continental ice to linger, allowing for the routing and rapid release of freshwater creating abrupt climate reversals (H1, YD and 8.2 kyr Event). Deep-ocean circulation during MIC 5e loses buoyancy in a fashion similar to the Holocene however, maximum flow velocities are curtailed for &sim7 kyr after the onset of interglacial conditions. This lag is best explained by the melting of Greenland into areas of NCW convection due to increased insolation forcing.
机译：本文利用近海和深海代理来了解北大西洋深水生产的变化，这与整个晚更新世和全新世期间淡水输入增加的时期有关。 Eirik Drift的取心地点的长期沉积速率超过15 cm / kyr。，从而可以在Milankovitch和千年时间尺度上进行古海洋学重建。从冰期北大西洋中层水（gNAIW）到海洋同位素年代（MIC）2的过渡全新世期间的大西洋深水（NADW）在第1章中进行了研究。早期全新世（9000-10,500 ka），21GGC岩心（3471 m）的沉积速率> 100 cm / kyr。表明gNAIW选出了上游冰川沉积物，沉积于21GGC。沉积物沉积物的增加一直持续到＆sim9ka，当长期速率稳定在40 cm / kyr。时，表明NADW密度已经稳定。从8.6到8.2 ka，阿加西兹湖冰川河的灾难性排水将淡水注入北大西洋，破坏了深海循环。第二章着重讨论了埃里克漂流1306号站点（2272 m）上过去的160年，那里的MIC沉积速率最高。 2-5d。在此间隔期间，可分选的淤泥（SS）和厚皮猪笼草的δ18O呈负相关，表明Eirik漂流上方的地表条件变化传播到深海中。在过去的40年中，SS的减少伴随着海洋表面清新的出现。这些间隔与海因里希事件有关，表明从大陆释放的大量冰流改变了深海循环。最后一章考察了1号和2号终端的深海响应。假定2号终端有更高的日照强迫，以促进大陆冰川的快速融化。 ，几乎没有机会在大陆上储存淡水。相反，终端1的日射量较低，使得大陆冰层可以留存下来，从而使淡水流向并迅速释放，从而产生了突然的气候逆转（H1，YD和8.2 kyr事件）。 MIC 5e期间的深海循环以与全新世相似的方式失去了浮力，但是在冰间条件出现后，＆sim7 kyr的最大流速降低了。最好的解释是，由于日照强迫的增加，格陵兰融化为NCW对流区域。

著录项

  • 作者

    Henderson, Samuel Straker.;

  • 作者单位

    Rutgers The State University of New Jersey - New Brunswick.;

  • 授予单位 Rutgers The State University of New Jersey - New Brunswick.;
  • 学科 Geology.Physical Oceanography.Geochemistry.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 173 p.
  • 总页数 173
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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