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和南极冰盖的变化动态。要更好地了解冰盖过去的历史，一种方法是从内陆冰中获得过去地质时期的记录，特别是在南极洲，世界上最大的剩余冰盖？S。这样的记录极其罕见，可以在横贯北极山脉中部的拉戈尔奇山脉的火山露头处获得。现在暴露在拉戈尔奇山脉内的火山在东南极冰盖下喷发，收集的数据将记录过去冰盖的厚度。此外，信息将被用来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西南极裂谷系统(WARS)的联系。这场战争是一片广阔的延展(即拉伸)的大陆地壳，类似于在东非发现的那样，火山活动广泛而持久(目前活跃的时间为6500万年)，尽管进行了50多年的研究，但南极洲火山活动和裂谷的根本原因仍存在激烈辩论。因此，该奖项的结果还可能影响整个西南太平洋区域(例如新西兰和澳大利亚)的大洋火山作用的研究，在这些地区，成分和年龄相似的火山场通过共同的岩浆来源和过程联系在一起。该项目包括一名研究生，作为其硕士项目的一部分，他将从事岩石学数据的收集、分析和解释工作。所提供的经验和专门的分析培训将提高学生S研究的质量，并优化他们未来的机会。这项拟议的工作促进了教师和学生在国内和国际上的合作，包括与为理科学生提供先进技术指导的多用户设施合作。结果将在同行评议的期刊、科学会议上的公开陈述和外联活动中广泛传播。岩石学和地球化学数据将通过极地岩石储存库传播给社区。对亚冰川喷发火山岩的研究已经发展到了这样的程度，它现在是建立精确快照？的最强大的替代方法。冰盖，包括多个关键的冰层参数。这类数据应包括对冰厚度、表面高度和稳定性的测量，这些测量将被用来验证或否定已发表的与海平面变化有关的冰动力学半经验模型。除了确定在火山形成期间是否存在南极东部的冰之外，还将使用数据来推导出同时代的冰厚度、表面海拔和基本热状况(S)，并使用40Ar/39Ar测年方法得出精确的新地质年代学。根据标准地球化学特征(主要、微量元素和锶、钕、铅、氧同位素)的测量结果，将研究这些火山与最近在东南极冰下发现的冰下隆起之间的可能关系，该隆起可能是裂谷侧向隆起。这座山脊从未被采集过样本，没有确定日期，其意义也不确定。这些数据将提供有关地球深处和南极大陆这一主要被冰覆盖且知之甚少的区域下地球动力学过程的重要新信息。

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.