Investigating Early Miocene Sub-ice Volcanoes in Antarctica for Improved Modeling and understanding of a Large Magmatic Province

对未来海平面上升的预测需要更好地了解格陵兰岛和南极冰盖的变化动态。更好地了解冰盖过去历史的一种方法是获取过去地质时期的内陆冰的记录，特别是在南极洲。这是美国现存最大的冰盖。这样的记录非常罕见，可以在横贯南极山脉中部的拉戈尔斯山脉的火山露头中获得。现在暴露在拉戈尔斯山脉的火山在南极东部冰盖下爆发，收集的数据将记录过去冰盖的厚度。此外，这些信息还将用于确定影响冰盖稳定性的冰盖底部的热条件。该项目还将调查南极洲火山活动的起源以及与南极西部裂谷系统（WARS）的联系。南极洲是一个广阔的伸展（即拉伸）大陆地壳的区域，类似于在东非发现的，火山活动分布广泛，寿命长（6500万年至今活跃），尽管有50多年的研究，南极洲火山作用和裂谷的根本原因仍然存在激烈的争论。因此，这一奖项的结果也可能影响整个西南太平洋地区（例如新西兰和澳大利亚）的海洋火山作用研究，在这些地区，具有相似组成和年龄的火山场由共同的岩浆来源和过程联系在一起。实地项目包括一名研究生，他将收集、分析和解释岩石学数据，作为他/她硕士项目的一部分。所提供的经验和专业分析训练将提高学生的素质。研究并优化他们未来的机会。拟议的工作促进教师和学生的国内和国际合作，包括与多用户设施合作，为理科生提供先进的技术指导。研究结果将在同行评议的期刊、科学会议上的公开报告和推广活动中广泛传播。岩石学和地球化学数据将通过极地岩石储存库向社区传播。对冰下喷发火山岩的研究已经发展到一定程度，它现在是建立精确“快照”的最有力的代理方法。冰盖，包括多个关键的冰参数。这些数据应包括冰厚、地表高程和稳定性的测量，这些数据将用于验证或拒绝已发表的有关冰动力与海平面变化的半经验模型。除了确定在火山形成期间南极东部是否存在冰外，数据还将用于推导同期冰厚度、地表高度和基础热状态，并使用40Ar/39Ar定年方法进行精确的新地质年代学。根据标准地球化学特征（主要、微量元素和Sr、Nd、Pb、O同位素）的测量推断，将用于研究火山与最近在南极东部冰下发现的冰下脊（可能是裂谷侧翼隆起）之间的可能关系。这个山脊从来没有被取样过，没有日期，它的意义也不确定。这些数据将提供重要的新信息，了解南极大陆这片大部分被冰覆盖、人们知之甚少的区域下的地球深部和地球动力学过程。

Predictions of future sea level rise require better understanding of the changing dynamics of the Greenland and Antarctic ice sheets. One way to better understand the past history of the ice sheets is to obtain records from inland ice for past geological periods, particularly in Antarctica, the world?s largest remaining ice sheet. Such records are exceedingly rare, and can be acquired at volcanic outcrops in the La Gorce Mountains of the central Transantarctic Mountains. Volcanoes now exposed within the La Gorce Mountains erupted beneath the East Antarctic ice sheet and the data collected will record how thick the ice sheet was in the past. In addition, information will be used to determine the thermal conditions at the base of the ice sheet, which impacts ice sheet stability. The project will also investigate the origin of volcanic activity in Antarctica and links to the West Antarctic Rift System (WARS). The WARS is a broad area of extended (i.e. stretched) continental crust, similar to that found in East Africa, and volcanism is wide spread and long-lived (65 million years to currently active) and despite more than 50 years of research, the fundamental cause of volcanism and rifting in Antarctica is still vigorously debated. The results of this award therefore also potentially impact the study of oceanic volcanism in the entire southwestern Pacific region (e.g., New Zealand and Australia), where volcanic fields of similar composition and age have been linked by common magma sources and processes. The field program includes a graduate student who will work on the collection, analysis, and interpretation of petrological data as part of his/her Masters project. The experience and specialized analytical training being offered will improve the quality of the student?s research and optimize their opportunities for their future. The proposed work fosters faculty and student national and international collaboration, including working with multi-user facilities that provide advanced technological mentoring of science students. Results will be broadly disseminated in peer-reviewed journals, public presentations at science meetings, and in outreach activities. Petrologic and geochemical data will be disseminated to be the community through the Polar Rock Repository.The study of subglacially erupted volcanic rocks has been developed to the extent that it is now the most powerful proxy methodology for establishing precise ?snapshots? of ice sheets, including multiple critical ice parameters. Such data should include measurements of ice thickness, surface elevation and stability, which will be used to verify, or reject, published semi-empirical models relating ice dynamics to sea level changes. In addition to establishing whether East Antarctic ice was present during the formation of the volcanoes, data will be used to derive the coeval ice thicknesses, surface elevations and basal thermal regime(s) in concert with a precise new geochronology using the 40Ar/39Ar dating method. Inferences from measurement of standard geochemical characteristics (major, trace elements and Sr, Nd, Pb, O isotopes) will be used to investigate a possible relationship between the volcanoes and the recently discovered subglacial ridge under the East Antarctic ice, which may be a rift flank uplift. The ridge has never been sampled, is undated and its significance is uncertain. The data will provide important new information about the deep Earth and geodynamic processes beneath this mostly ice covered and poorly understood sector of the Antarctic continent.