Rift Mechanisms and Thermal Regime of the Lithosphere across Beardmore Glacier Region, Central Transantarctic Mountains, from Magnetotelluric Measurements

大地电磁测量显示横贯南极山脉中部比尔德莫尔冰川地区岩石圈的裂谷机制和热状况

• 批准号: 0838914
• 负责人: Philip Wannamaker
• 金额: $ 43.02万
• 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: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2012-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0838914&HistoricalAwards=false
• 关键词: Rift; Mechanisms; Thermal; Regime; Lithosphere

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). The investigators will examine competing hypotheses for the mechanism of extension and creation of the Transantarctic Mountains, and evolution of the thermal regimes of rifted West Antarctica and stable East Antarctica using magnetotelluric (MT) profiles. Surrounded almost entirely by ocean ridges, Antarctica is a special tectonic situation because of the need to make accommodation space for rifting in the Transantarctic region. 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, or more. Geophysical methods, such as MT, are appropriate in Antarctica because of the predominance of thick ice cover over most of the Continent and the difficult operating environment. The proposed effort will consist of approximately 50 sites over a distance approaching 500 km with a 10 km average spacing, oriented normal to the Transantarctic Mountains (TAM), in the Beardmore glacier area. High quality MT soundings will be collected over thick ice sheets using a custom electrode preamp design, updated from previous Antarctic projects. Data acquisition will take place over two field seasons. The primary goals are three-fold: to establish the location of the deeper tectonic transition between East and West Antarctica that may be offset from the physiographic transition at the surface, using deep resistivity structure distinguish between modes of extensional upwelling and magmatism that may be vertically non-uniform, depth and magnitude of quasi-layered deep crustal low resistivity, particularly below West Antarctica, will be used to estimate crustal heat flux into the ice sheet base.

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。调查人员将利用大地电磁（MT）剖面研究跨南极山脉的延伸和形成机制以及断裂的西南极洲和稳定的东南极洲的热状态演变的相互竞争的假设。南极洲几乎完全被洋脊包围，是一个特殊的构造环境，因为需要为横贯南极洲的裂谷提供容纳空间。在MT方法中，地球自然电磁场的时间变化被用作源场，以探测1至200 km或更深深度范围内的电阻率结构。地球物理方法，如大地电磁法，适用于南极洲，因为南极洲大部分地区都有厚厚的冰层覆盖，而且作业环境困难。拟议的工作将包括大约50个地点，距离接近500公里，平均间距为10公里，方向垂直于Beardmore冰川地区的跨南极山脉。高质量的大地电磁测深将收集厚冰盖使用定制的电极前置放大器设计，从以前的南极项目更新。数据采集将在两个野外季节进行。主要目标有三个方面：确定东南极洲和西南极洲之间较深的构造过渡位置，该位置可能偏离地表的地文过渡，利用深电阻率结构区分可能垂直不均匀的伸展上涌和岩浆活动模式，准层状深地壳低电阻率的深度和幅度，特别是在西南极洲以下，将被用来估计进入冰盖底部的地壳热通量。