Investigating Lithospheric Evolution Beneath the Southern and Northeastern United States

研究美国南部和东北部的岩石圈演化

• 批准号: 1614860
• 负责人: Aibing Li
• 金额: $ 15.99万
• 依托单位: University of Houston
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-06-01 至 2019-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1614860&HistoricalAwards=false
• 关键词: Investigating; Lithospheric; Evolution; Beneath; Southern

Throughout Earth?s history, the tectonic plates that make up the lithosphere have converged to form super-continents and then pulled apart over time-scales of hundreds of millions of years. The southern U.S. near the Gulf Coast and the eastern U.S. bordering the Atlantic experienced two cycles of super-continent formation and break-up. These episodes of collision and rifting altered the crust and mantle lithosphere of the North American plate, thickening these layers in some regions, thinning them in others, and producing distinctive structures by aligning mineral grains and melting small amounts of rock. In this project we will use earthquake waves to construct three-dimensional models of the crust and mantle lithosphere, and we will interpret these models to better understand how continental collision and rifting affect continental lithosphere.The goal of this work is to improve resolution of crust and mantle structure in the southern and eastern U.S. in order to better understand lithospheric evolution and modification through the last Wilson cycle. The southern and eastern margins of the North America continent experienced two complete Wilson cycles of orogeny and rifting, leaving varied signatures of deformation and magmatism in the crust and mantle lithosphere of these regions. However, many aspects of crust and mantle structure remain poorly known at the scales relevant to distinguishing the effects of orogeny, rifting, and other processes such as hotspot interaction. Using data from the NSF EarthScope USArray/Transportable Array (TA), now completed in the contiguous U.S., we propose to image crust and mantle seismic structure in new detail. We will focus on two regions: one spanning the southern craton edge, the entire Ouachita orogeny and the Gulf of Mexico coastal plain, and the other containing the eastern craton edge, the central and northern Appalachians, and the Atlantic coast. We will use seismic data from TA stations, supplemented by other temporary and permanent broadband stations, to image crustal and mantle discontinuities using Sp and Ps receiver functions, construct 3-D anisotropic models based on Rayleigh wave, Love wave and shear-wave-splitting analyses, and we will integrate these data and methods through joint analyses and inversions. The seismic models will be used constrain the style and geometry of deformation in the crust and mantle lithosphere due to the last episodes of orogeny and rifting. This interpretation will be guided by geological and active source indicators of deformation in the shallow crust and by the type and age of magmatism across the region, bearing in mind that some facets of crust and mantle structure may reflect events that predated or followed the last cycle of orogeny and continental rifting. Variations in the impact of orogeny and rifting on the lithosphere will be compared between and within the study regions. The proposed project will support the education and career development of graduate students at the University of Houston and at Brown. It will also contribute to undergraduate senior theses, lab exercises and group research projects in undergraduate and graduate courses, and to science outreach activities with local public schools. Students from diverse backgrounds will be recruited to participate in this research.

在整个地球的历史中，构成岩石圈的构造板已经融合形成了超级容器，然后随着数亿年的时间尺度拉开。 在墨西哥湾沿岸和美国东部与大西洋接壤的美国东部的美国南部经历了两个超大型地层和分裂的周期。 这些碰撞和裂谷的发作改变了北美板块的地壳和地幔岩石圈，在某些地区增厚这些层，在其他地区稀疏，并通过对齐矿物谷物并熔化少量岩石来产生独特的结构。 在这个项目中，我们将使用地震波来构建外壳和地幔岩石圈的三维模型，我们将解释这些模型，以更好地了解大陆碰撞和裂变如何影响大陆岩石圈。这项工作的目的是改善美国南部和东部在美国的地壳和壁炉结构的分辨率，以便更好地了解岩石层层次的质地化和修改岩石层的循环循环。北美洲大陆的南部和东部边缘经历了两个完整的造山基和裂痕的全部威尔逊周期，在这些地区的地壳和地幔岩石圈中留下了各种变形和岩浆的特征。 然而，在与区分造口，裂谷和其他过程（例如热点相互作用）的影响相关的尺度上，地壳和地幔结构的许多方面仍然鲜为人知。 使用NSF Earthscope USArray/可运输阵列（TA）的数据，现在在美国连续的美国完成，我们建议以新的细节对地壳和地幔地震结构进行图像。 我们将重点关注两个区域：一个跨越南部克拉通边缘，整个瓦希塔造山基因和墨西哥沿岸平原，另一个横跨墨西哥沿海地区，另一个横跨克拉通边缘，中部和北部的阿巴拉契亚人以及大西洋沿岸。 我们将使用来自TA车站的地震数据，并补充了其他临时和永久宽带站，以使用SP和PS接收器功能来对地壳和地幔不连续性进行构图，构建基于Rayleigh Wave，Love Wabe Wave和Sharear-Splave-Splations分析的3-D各向异性模型，并且我们将通过关节分析集成这些数据和方法。 地震模型将用于约束由于造口和裂谷的最后发作，因此在地壳和地幔岩石圈中的变形的样式和几何形状。 这种解释将由浅层地壳中变形的地质和主动源指标以及整个地区的岩浆主义的类型和年龄进行指导，请记住，壳和地幔结构的某些方面可能反映出前面或遵循最后一个造型和大陆裂隙的周期的事件。 研究区域之间和内部将比较造口和裂谷对岩石圈的影响的变化。拟议的项目将支持休斯顿大学和布朗大学研究生的教育和职业发展。它还将为本科和研究生课程的本科高级论文，实验室练习和小组研究项目以及与当地公立学校的科学外展活动做出贡献。 来自不同背景的学生将被招募参加这项研究。