Collaborative Research: Heat Source and Flux Distributions in the Western Ross Sea Seafloor

了解冰冻圈底部可用热量的来源和性质，对于破译南极洲及其海洋中冰的范围和停留时间至关重要。控制冰盖稳定性的参数约束、地壳对冰加载和卸载的响应、火山活动和地球内部热量对上覆冰的影响是全球气候变化界广泛关注的问题。本研究的目的是确定并记录罗斯海西南部海底的热源和热通量分布。地热热通量是形成和控制冰流、海洋环流和生态系统的基本参数之一，与冰下水文及其对冰盖滑动和内部变形能力的影响有关。尽管这很重要，特别是在南极环境中，但在罗斯海进行的关于岩石圈热通量如何随时间影响冰冻圈动力学的研究很少。该项目研究地点位于罗斯海西部海底，包括恐怖裂谷，它代表了南极西部裂谷系统最年轻的扩展阶段，这是世界上最大的裂谷之一，也是唯一一个被大陆冰盖覆盖的裂谷。变薄的西罗斯海岩石圈和恐怖裂谷包含了500万年至今的活跃火山活动，表明这一时期上新世-第四纪断层运动和冰盖范围和厚度的动态变化与岩浆活动同时发生。该项目将对罗斯海西部海底进行船载调查。收集的数据集包括海底热流/电导率测量、实时海底可视化、水柱热液信号采集以及通过疏浚进行岩石取样。热流和直接海底观测将为海底-海洋相互作用提供一个前所未有的背景，解决了限制罗斯海生态系统的水柱中的一些生物地球化学循环（例如，海底火山活动和由此产生的热液系统对水柱的化学和营养贡献）。所有数据的汇编将能够检验罗斯海西部的岩浆侵入和火山活动是影响该地区海洋-冰冻圈系统动力学的主要岩石圈热源的假设。收集到的数据还将使我们能够完善当前的时间序列和地球动力学，从而驱动世界上主要的大陆裂谷系统之一。该项目的交付成果将是新的地理空间信息数据，包括该地区所有正在进行的地球物理网格，这些数据可以通过NSF资助的数据存储库公开获取。在获得地球化学和地质年代学信息后，剩余的岩石样本将被保存在极地岩石储存库。培养博士后1人，研究生2人，本科生3人以上。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Understanding the origins and nature of heat available at the base of the cryosphere is essential in deciphering the extent and residence time of the ice in Antarctica and its oceans. Constraints on parameters that control ice-sheet stability, response of the crust to ice loading and unloading, and the effects of volcanism and heat from Earth’s interior on overlying ice is of broad interest to the global climate change community. The goal of this study is to identify and to document the distribution of heat source and heat flux within the seafloor of the southwestern Ross Sea. Geothermal heat flux is one of the basic parameters that shape and control ice flow, ocean circulation, and ecosystem, connecting with subglacial hydrology and its influence on the ability of the ice sheet to slide and internally deform. Despite the importance, particularly in the Antarctic environments, there have been few investigations made in the Ross Sea on how lithospheric heat flux contributes to cryospheric dynamics over time. The project study site in the western Ross Sea seafloor comprises the Terror Rift, which represents the youngest phase of extension within the West Antarctic Rift System, one of the world’s largest rifts and the only one covered by continental ice sheets. The thinned western Ross Sea lithosphere and Terror Rift encompasses active volcanism that range from 5 million years to present-day, suggesting that Pliocene-Quaternary fault movement and dynamic changes in ice sheet extent and thickness over this period are concurrent with magmatic activities.This project will conduct a shipboard survey of the western Ross Sea seafloor. The datasets to be collected include seafloor heatflow/conductivity measurements, real-time seafloor visualization, water-column hydrothermal signal acquisition, and rock sampling via dredging. Heat flow and direct seafloor observations will provide an unprecedented context for seafloor-ocean interactions, addressing some of the biogeochemical cycles in the water column (e.g., chemical and nutrients contributions to the water column from seafloor volcanism and resultant hydrothermal systems) in constraining Ross Sea ecosystems. The compilation of all the data will enable the testing of hypotheses that magmatic intrusion and volcanism in the western Ross Sea is the primary lithospheric heat source that has influenced the dynamics of the ocean-cryosphere system in this region. Data collected will also allow us to refine current timeseries and geodynamics that drive one of the world’s major continental rift systems. Deliverables from this project will be new geospatial information data, including all the underway geophysics grids of the area, publicly available via NSF funded data repositories. After acquiring geochemistry and geochronology, the remaining rock samples will be archived at the Polar Rock Repository. The project will also train 1 postdoc, 2 graduate students, and at least 3 undergraduate students.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.