Collaborative Research: Coring the Line Islands Ridge for Paleoceanographic Research

全球气候的两个关键特征——热带辐合带（ITCZ）和厄尔尼诺南方涛动（ENSO）——过去的行为变化目前尚不清楚。需要海洋沉积物的连续记录来为全新世期间这些以及其他气候和海洋模式的古重建提供信息。该项目将尝试从热带太平洋中部的莱恩群岛海岭获取此类记录，该地区是一个关键且敏感的地点，现有样本或数据很少。 由于多种原因，莱恩群岛山脊是捕捉沉积物中记录的古海洋和古气候变化的理想地点。首先，ITCZ 和 ENSO 在该地区不像其他地方那样容易受到季节或空间变化的影响。此外，由于莱恩群岛海脊处于测深高点，因此与附近深海环境相比，含有古环境代理指标的碳酸钙贝壳受到溶解的影响较小。佐治亚理工学院、哥伦比亚大学拉蒙特-多尔蒂地球观测站、罗德岛大学海洋学研究生院、德克萨斯农工大学、波士顿大学和加州大学圣克鲁斯分校的研究人员将合作对莱恩群岛山脊进行勘察取芯调查。在 R/V Langseth 上进行研究巡航期间，PI 将收集测深和地球物理数据，以限制最佳取芯位置；一旦确定了最佳位置，他们将在每个地点收集一套物理样本（初始重力核心、CTD/Niskin 花环铸件、活塞核心和多核心）。岩心分析将包括使用扫描 XRF 确定沉积物成分，以及使用浮游有孔虫的氧同位素开发地层和年龄模型。 此次勘察工作的核心数据和相关数据将提供给更广泛的社区，以促进未来对数万至数十万年范围内的古气候和海洋变化的研究。该领域的专家预计使用这些数据集可以更好地了解该地区过去的 ITCZ 和 ENSO 行为、海面温度、海洋化学、生产力、营养物和沉积物循环以及风尘输入的变化。此外，这些数据集将为校准古气候模型提供额外的机会，并可用于支持地理上重叠的美国国务院倡议（海洋法？扩展大陆架计划）。其他更广泛的影响包括通过将物理数据（核心）添加到 LDEO 样本存储库、通过 SESAR（地球样本注册系统）对样本进行编目以及将相关数据集贡献给可广泛访问的数据库（SedDB、NCDC）来加强科学基础设施和传播信息。该项目还将包括对几名研究生的培训。最后，该项目的多方面方法将为 NSF 提供评估 R/V Langseth 多用途功能的机会。

Past changes in the behavior of two key features of the global climate, the Intertropical Convergence Zone (ITCZ) and the El-Nino Southern Oscillation (ENSO), are not clearly understood at present. Continuous records from marine sediments are needed to inform paleoreconstructions of these and other climatic and oceanographic patterns during the Holocene. This project will attempt to acquire such records from the Line Islands Ridge in the Central Tropical Pacific, a key and sensitive location with little in terms of existing samples or data. The Line Islands Ridge is an ideal site to capture paleooceanographic and paleoclimatic changes recorded in sediment for a number of reasons. First, the ITCZ and ENSO are not as susceptible to seasonal or spatial variation in this region as they are elsewhere. In addition, because the Line Islands Ridge is a bathymetric high, the calcium carbonate shells that contain the paleoenvironmental proxy indicators are less likely to be affected by dissolution than in nearby deep ocean settings. Researchers at the Georgia Institute of Technology, Columbia University's Lamont-Doherty Earth Observatory, the Graduate School of Oceanography at the University of Rhode Island, Texas A&M University, Boston University, and the University of California at Santa Cruz will collaborate to conduct a reconnaissance coring survey of the Line Islands Ridge. During a research cruise aboard the R/V Langseth, the PIs will collect bathymetric and geophysical data to constrain optimal coring locations; once optimal locations are established, they will collect a suite of physical samples (an initial gravity core, a CTD/Niskin rosette cast, a piston core, and a multi-core) at each site. Analyses of the cores will include determination of sediment composition using scanning XRF, as well as development of stratigraphic and age models using oxygen isotopes from planktonic foraminifera. Cores and associated data from this reconnaissance effort will be made available to the broader community in order to facilitate future research on paleoclimatic and -oceanographic change over scales of tens to hundreds of thousands of years. Experts in the field foresee using these datasets to better understand past changes in ITCZ and ENSO behavior, sea surface temperature, ocean chemistry, productivity, nutrient and sediment cycling, and eolian dust inputs in the region. Furthermore, these datasets will provide additional opportunities to calibrate paleoclimate models, and may be used to support a geographically overlapping US State Department initiative (Law of the Sea?Extended Continental Shelf program). Additional broader impacts include enhancing scientific infrastructure and disseminating information by adding physical data (cores) to the LDEO sample repository, cataloguing samples through SESAR (System for Earth Sample Registration), and contributing the associated datasets to widely accessible databases (SedDB, NCDC). This project will also involve training for several graduate students. Finally, the multi-faceted approach of this project will provide NSF with an opportunity to evaluate the multi-purpose functionality of the R/V Langseth.