Collaborative Research: Understanding Lithospheric Suturing and Passive Margin Development Beneath the Southeastern U.S.

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。在建造阿巴拉契亚山脉的岩石圈吸积的顶峰（2.5 - 3.2亿年前），另一个大陆（冈瓦纳）的岩石圈与原北美碰撞。这两个岩石圈之间的缝合线在格鲁吉亚南部的地壳下划定的化石，岩石类型和年龄的变化，和一个向南倾斜的反射区的地震反射数据成像。 本项目的目标是确定地幔中岩石圈缝合线的位置和形状，并测量缝合线上地壳和地幔物理和化学性质的差异。将85个EarthScope USAray柔性阵列宽带站部署在横跨缝线的两个N-S线性阵列中。一条线路从北卡罗来纳州延伸到佛罗里达狭长地带的海岸。另一条从南卡罗来纳州延伸到佛罗里达中部。这些台站与EarthScope USAray便携式阵列台站一起，将记录来自地球仪各地的地震波。将对这些数据进行分析，以测量各向同性和各向异性波速的三维变化，并根据温度、岩石成分（包括挥发分含量）和岩石变形组构解释速度模型。地壳缝合线如何连接到地幔结构？地幔增生发生在浅倾剪切带上，还是至少部分发生在更垂直的接触上，这意味着在一个广泛的深度范围内水平缩短？如果存在倾斜地幔界面，它们是残留的俯冲岩石圈，还是与以前的俯冲无关的剪切带？地震波速度的各向异性对吸积过程中的变形分布意味着什么？与冈瓦纳大陆和劳伦提斯大陆碰撞有关的俯冲方向是什么？岩石圈碰撞之后，大陆分裂，导致大西洋打开。大陆岩石圈如何受到这一幕伸展、裂谷和岩浆作用的影响？有岩石圈分层的证据吗？现今岩石圈下面的弱地幔软流圈中的流动模式是什么？该项目直接支持研究生和本科生的教育和培训。我们正在开发教育材料，利用这个研究项目来建立对大陆碰撞，造山和大陆分裂等概念的理解。实验结果将用于我们的本科生和研究生课程，并推广到我们在格鲁吉亚，北卡罗来纳州和罗得岛的家乡机构附近的学校。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).At the culmination of the lithospheric accretion that built the Appalachian Mountains (250-320 million years ago) the lithosphere of another continent (Gondwana) collided with proto-North America. The suture between these two lithospheres is delineated in the crust beneath southern Georgia by variations in fossils, rock types and ages, and a zone of southward dipping reflectors imaged by seismic reflection data. However, the location and geometry of the suture in the mantle is unknown.The goal of this project is to determine the position and shape of the lithospheric suture in the mantle, and to measure any contrasts in crust and mantle physical and chemical properties across the suture. 85 EarthScope USArray Flexible Array broadband stations are being deployed in two N-S linear arrays that straddle the suture. One line stretches from North Carolina to the coast of the Florida panhandle. The other extends from South Carolina into central Florida. These stations, together with the stations of the EarthScope USArray Transportable Array, will record seismic waves from around the globe. These data will be analyzed to measure three-dimensional variations in isotropic and anisotropic wave velocities, and the velocity models will be interpreted in terms of temperature, rock composition (including volatile content), and rock deformation fabrics.This research will address a series of fundamental questions. How does the crustal suture connect to mantle structures? Did mantle accretion occur on shallow dipping shear zones, or did it occur at least in part on more vertical contacts that imply horizontal shortening over a broad depth range? If dipping mantle interfaces exist, do they represent relict subducted lithosphere, or are they shear zones unrelated to prior subduction? What does anisotropy in seismic velocities imply about the distribution of deformation during accretion? What was the direction of subduction associated with the collision of Gondwana and Laurentia? Continental break-up followed the lithospheric collision, leading to the opening of the Atlantic Ocean. How was the continental lithosphere affected by this episode of extension, rifting and magmatism? Is there evidence for delamination of the lithosphere? What are the present-day patterns of flow in the weak mantle asthenosphere that underlies the lithosphere?This project is directly supporting the education and training of graduate and undergraduate students. We are developing educational materials that use this research project to build understanding of concepts such as continental collision, mountain building, and continental break-up. Experiment results will be used in our undergraduate and graduate classes, and in outreach to schools in the vicinity of our home institutions in Georgia, North Carolina, and Rhode Island.