MAGIC MT - Uplift of the Appalachians

北美大陆的东部边缘远离目前活跃的构造板块边界，因此在板块构造方面通常被认为是相对“安静”的。 然而，北美东缘经历了漫长而丰富的板块构造历史，最近参与了北美和欧洲的解体以及大西洋的形成。 这一分裂涉及多个重要的地质过程，包括岩浆活动，大陆的拉伸，以及导致阿巴拉契亚山脉形成的隆起。虽然大部分活动在很久以前就结束了，但有证据表明阿巴拉契亚山脉现在甚至部分受到山脉下方地幔流动的支撑。我们正在使用在地表记录的地球电场和磁场来成像大陆的结构和下面的对流地幔的特性，以便更好地了解控制现代地形的过程以及与大陆分裂或裂谷有关的过程。该项目部分支持博士生的教育以及高技能技术人员的培训，实验使用Cape Abilities制造的设备，Cape Abilities是科德角的一家非营利公司，为残疾人找到工作。技术摘要我们正在进行实地工作，收集阿巴拉契亚山脉从俄亥俄州到弗吉尼亚州约28个站点的大地电磁（MT）数据。 大地电磁法测量地球表面自然产生的电场和磁场，并利用这些信息对地表以下数百公里深处的结构进行成像。该方法测量地球传导电流的能力，这是一种对温度以及水或岩浆等流体的存在敏感的特性。我们可以构建沿着剖面的整个长度沿着的深层结构的横截面图像。 该调查与正在进行的地震实验相吻合，我们正在与该项目的主要研究人员合作，对限制岩石圈厚度、地幔水合状态以及与地幔上涌相关的任何部分熔融的存在的结果进行协调的联合解释。

Non-technical summaryThe eastern edge of the North American continent is located far from currently active boundaries of tectonic plates, and is thus often considered relatively "quiet" in plate tectonic terms. However, the eastern margin of North America has experienced a long and rich plate tectonic history, most recently being involved in the break-up of North America and Europe and the formation of the Atlantic Ocean. That break-up involved multiple important geologic processes, including magmatism, stretching of the continent, and uplift that is responsible for the formation of the Appalachian Mountains.Although most of this activity finished long ago, there is evidence to suggest the Appalachians are even now being partially supported by flow of the mantle beneath the mountains. We are using electric and magnetic fields of the earth recorded at the surface to image the structure of the continent and the properties of the underlying convecting mantle, in order to better understand the processes that control modern day topography and those involved in continental break-up, or rifting. The project partly supports the education of a PhD student as well as training of highly skilled technical staff, and the experiment uses equipment manufactured by Cape Abilities, a non-profit company on Cape Cod that finds work for people with disabilities.Technical summaryWe are carrying out fieldwork to collect magnetotelluric (MT) data in a profile of about 28 stations across the Appalachians, from Ohio to Virginia. The MT method measures naturally occurring electric and magnetic fields at the surface of the earth, and uses this information to image structure to depths of several hundred km below the surface. The method measures the ability of the earth to conduct electrical current, a property that is sensitive to temperature as well as to the presence of fluids such as water or magma. We can construct a cross sectional image of the deep structure along the entire length of the profile. The survey is coincident with an ongoing seismic experiment, and we are working with the principal investigators of that project to carry out a coordinated joint interpretation of results constraining lithospheric thickness, hydration state of the mantle, and the presence of any partial melt associated with mantle upwelling.