Geodynamics and Thermal Regime across the Central Transantarctic Mountains from Analysis of Magnetotelluric Measurements

从大地电磁测量分析中跨南极中部山脉的地球动力学和热力状况

• 批准号: 1243559
• 负责人: Philip Wannamaker
• 金额: $ 17.33万
• 依托单位: University of Utah
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-12-01 至 2016-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1243559&HistoricalAwards=false
• 关键词: Geodynamics; Thermal; Regime; across; Central

Intellectual Merit: The PIs propose to analyze a transect of 57 high-quality magnetotelluric (MT) soundings acquired over two Antarctic field seasons to examine competing hypotheses for the mechanism of extension and creation of the Transantarctic Mountains. These data will also be used to characterize the thermal regimes of rifted West Antarctica and stable East Antarctica. In the MT method, temporal variations in the Earth's natural electromagnetic field are used as source fields to probe the electrical resistivity structure in the depth range of 1 to 200 km below Earth's surface. Raw MT soundings contain significant information related to the thermal regime beneath the Transantarctic Mountains as it relates to support mechanisms and composition. This information will enable comparison to other rift-platform transitions, such as in the western United States. The distinct character of the MT data will also be correlated with regional aeromagnetic trends and tied to outcrops in terms of distinct lithologies such as meta-sedimentary terranes and plutonic complexes. Specifically, the goals of this research are: to establish the location of the tectonic transition between East and West Antarctica, which may help infer a support mechanism for the Transantarctic Mountains; to use MT data to estimate crustal heat flux into the ice sheet base; and to determine if regional-scale resistivity properties be used as a proxy for lithological discrimination, to support facies extrapolation and terrane reconstruction.Broader impacts: This project involves international collaborations between University of Utah, GNS Sciences Wellington NZ, and Tokyo Institute of Technology Japan. It will support a female post-doc who will gain experience in state of the art geophysical instrumentation, parameters of field survey design, practical logistical matters in remote settings, modern methods of MT inversion, and the relationship between electrical resistivity and physico-chemical state in the Earth. Heat flow estimates could improve models of ice sheet stability.

知识价值：PIs建议分析在两个南极野外季节获得的57个高质量大地电磁测深样带，以检验关于横贯南极山脉延伸和形成机制的相互竞争的假设。这些数据还将用于描述断裂的西南极洲和稳定的东南极洲的热状态。在大地电磁法中，利用地球自然电磁场的时间变化作为源场，探测地表以下1 ~ 200 km深度范围内的电阻率结构。原始的大地电磁测深包含了与横贯南极山脉下的热状态有关的重要信息，因为它与支撑机制和成分有关。这些信息将有助于与其他裂谷平台过渡进行比较，例如美国西部的裂谷平台过渡。MT数据的独特特征也将与区域航磁趋势相关，并与不同岩性的露头联系起来，如变质沉积地体和深成杂岩。具体而言，本研究的目标是：确定东西南极洲之间的构造过渡位置，从而有助于推断横贯南极山脉的支撑机制；利用MT资料估算进入冰盖基底的地壳热通量；并确定区域尺度电阻率特性是否可以作为岩性判别的代表，以支持相外推和地层重建。更广泛的影响：该项目涉及犹他大学、新西兰惠灵顿GNS科学公司和日本东京工业大学之间的国际合作。该项目将支持一名女性博士后，她将在最先进的地球物理仪器、野外调查设计参数、偏远地区的实际后勤问题、现代大地电磁学反演方法以及地球电阻率与物理化学状态的关系等方面获得经验。热流估算可以改进冰盖稳定性模型。