COLLABORATIVE RESEARCH: Tracing Greenhouse to Icehouse Climate Evolution Along the Western North Atlantic Meridional and Paleodepth Transect

在过去的6500万年里，地球的气候发生了巨大的变化，从温暖的始新世“温室世界”到寒冷的“冰窖世界”，冰川周期性地向中纬度地区推进。在这段时间里，地球接收到的太阳能变化很小，因此地球系统内部的变化导致了观测到的大部分气候变化。大陆的位置、洋流的变化以及影响大气中温室气体水平的碳循环的变化都在地球气候的演变中发挥了重要作用。北大西洋的海洋学变化是导致更新世周期性大冰期的一个重要因素，北大西洋也被假设为数百万年前气候变暖时期的一个重要气候驱动因素。在国际海洋发现计划（IODP）的支持下，研究小组设计了一项现场调查，以确定从北大西洋西部收集沉积物部分的目标。地震反射调查和沉积物记录将用于详细研究海洋在过去6000万年中的变化，包括记录更新世前温暖间隔的海洋温度、深水流量和温室气体水平的变化。这些记录还将用于更好地了解大陆构造和温室气体如何协同作用，以稳定温暖的气候。研究更新世前的气候也将帮助科学家了解未来可能影响气候敏感性的过程。安全科学的钻探需要高质量的海底成像来确定合适的钻探地点。该项目的核心是使用Scripps便携式高分辨率地震系统进行为期31天的多通道地震调查。该调查将包括数字地震反射剖面采集和每个拟议钻探地点的多波束测绘。这些数据不仅将为钻井提供所需的数据，而且还将产生随着深水生产来源随时间变化而变化的沉积物分布的地震图像。数字地震反射剖面将把新提议的地点与现有的DSDP钻探地点联系起来，以取代目前可用的低质量模拟地震数据。该项目还将包括对北大西洋旧DSDP岩心中新世变化的调查研究，利用约束良好的磁反转地层学，将北部成分水的生产证据与海面温度梯度、CaCO3溶解和生物成因生产的变化进行比较。这是建立在最近的观察之上的，即中新世中晚期的冷却在非常高的北纬地区相对于深海和南大洋的冷却被推迟了，并将测试冷却在纬度上是历时性的假设。IODP钻探最终将提供连续的始新世-全新世沉积记录，解决轨道周期问题，与太平洋的类似记录进行比较。该项目支持罗格斯大学的研究生培训，并通过“联合首席科学家培训”项目为其他研究生提供航海经验。

Earth's climate has changed dramatically in the last 65 million years, from a warm Eocene "greenhouse world" in which the polar regions were temperate and ice-free, to the cold "icehouse world" where glaciers periodically advanced to the mid-latitudes. Solar energy received by the earth has changed little in that time period, so variations internal to the earth system have caused the majority of the observed climate change. Position of continents, changes in ocean currents, and changes in the carbon cycle that affect the atmospheric level of greenhouse gases have all played important roles to in the evolution of Earth's climate. Oceanographic variability in the North Atlantic Ocean has been an important factor for causing periodic large glaciations in the Pleistocene, and the North Atlantic is also hypothesized to be an important climate driver under warmer climate regimes millions of years ago. The research team has designed a site survey to locate targets for collecting sediment sections from the Western North Atlantic under the auspices of the International Ocean Discovery Program (IODP). The seismic reflection survey and sediment records will be used study in detail how the ocean has changed over the last 60 million years, including documenting changes in ocean temperature, deep water flow, and greenhouse gas levels in pre-Pleistocene warm intervals. The records will also be used to better understand how continental configurations and greenhouse gases functioned in tandem to stabilize warm climates. Studying pre-Pleistocene climates will also help scientists understand processes that are likely to affect climate sensitivity in the future. Safe scientific drilling requires high-quality sub-seafloor imaging to identify suitable drill sites. The centerpiece of this project is a 31-day multichannel seismic survey using the Scripps portable high-resolution seismic system. The survey will consist of digital seismic reflection profile acquisition and multibeam mapping at each proposed drill site. These data will not only provide required data for drilling, but also will produce seismic images of changing sediment distribution as sources of deep-water production change through time. Digital seismic reflection profiles will tie the new proposed sites to existing DSDP drill sites to replace poor quality analog seismic data now available. The project will also include a reconnaissance study of Miocene change from legacy DSDP cores in the North Atlantic with well-constrained magnetic reversal stratigraphy to compare evidence for production of Northern Component Water with changes in sea surface temperature gradients, CaCO3 dissolution, and biogenic production. This builds on recent observations that cooling during the middle to late Miocene was delayed in the very high northern latitudes relative to cooling of the deep sea and southern ocean, and will test the hypothesis that cooling was diachronous across latitudes. The IODP drilling will eventually provide continuous Eocene-Holocene sedimentary records that resolve orbital periodicities to compare to similar records from the Pacific. The project supports graduate student training at Rutgers University, and provides sea going experiences for additional graduate students through a "co-chief scientist in training" program.