Final stages of breakup and early spreading history of the Eastern North America passive margin from multichannel seismic data

多道地震数据显示北美东部被动边缘破裂的最后阶段和早期扩张历史

• 批准号: 1551807
• 负责人: Anne Becel
• 金额: $ 20万
• 依托单位: Columbia University
• 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: 2016-03-15 至 2019-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1551807&HistoricalAwards=false
• 关键词: Final; stages; breakup; early; spreading

Rifted passive margins record the full geologic history of rifting, from rift onset to continental breakup to the initiation of seafloor spreading and post-rift evolution of the margin. This project focuses on the Eastern North America continental margin offshore Cape Hatteras that was formed after the breakup of supercontinent Pangaea. A large suite of data has been collected across the transition from continental crust to oceanic crust in this region. These data will be analyzed and interpreted to obtain an improved understanding of events surrounding the final stage of continental breakup including the relationship between the timing of rifting and the occurrence of offshore magmatism and early opening of the Central Atlantic Ocean. The project will also provide new information on landslides that have occurred along the margin of the U.S. and an estimate of the number of landslides that might have produced tsunamis. A postdoctoral researcher will be trained in geophysical data analysis and interpretation, and the results of the proposed work will be incorporated into outreach programs for high school and middle school students.This project consists of the processing and interpretation of offshore, long-offset multichannel seismic (MCS) data from the Eastern North American Margin. The long-offset MCS data analysis will provide critical new information about the along-strike variations of the complex transitional crust between unambiguous continental and oceanic crust at a smaller-scale than previous studies. The crustal-scale closely-spaced MCS profiles will be essential to image the small-scale heterogeneities of the volcanic products along the margin, spatial patterns in basement topography, thickness of sediment and rift unconformities within the sediments and features within the crust and lithosphere (e.g., faults and crustal thickness variations). MCS imaging of those features are needed to assess the late-stage rifting processes and variations in time and space of these processes. Different kinematic plate models for the earliest stage of evolution of the Central Atlantic Ocean make very different predictions for the half spreading rate. In addition, large-scale segmentation at the modern Mid-Atlantic ridge has also been proposed to be inherited from the geometry of the adjacent continental margin. MCS data from this project will constrain variations in basement roughness, crustal thickness and crustal structure and reflectivity along and across new oceanic crust that will provide important constraints on the early seafloor spreading history and will help to distinguish between competing models.

裂谷被动边缘记录了裂谷作用的全部地质历史，从裂谷开始到大陆解体，再到海底扩张的开始和边缘的裂谷后演变。该项目的重点是在超大陆泛大陆分裂后形成的北美东部大陆边缘的哈特拉斯角近海。在该区域从大陆地壳向洋壳过渡的各个阶段收集了大量数据。 将对这些数据进行分析和解释，以更好地了解大陆分裂最后阶段的事件，包括裂谷时间与近海岩浆活动发生和中大西洋早期开放之间的关系。 该项目还将提供有关美国边缘沿着发生的山体滑坡的新信息，以及可能产生海啸的山体滑坡数量的估计。 一名博士后研究员将接受地球物理数据分析和解释方面的培训，拟议工作的结果将纳入面向高中和中学生的外联方案。该项目包括处理和解释北美东部边缘的海上长偏移距多道地震（MCS）数据。长偏移距MCS数据分析将以比以往研究更小的尺度提供关于明确大陆地壳和大洋地壳之间复杂过渡地壳沿走向变化的重要新信息。地壳尺度的密集MCS剖面图对于以下方面的成像至关重要：火山产物沿着边缘的小尺度不均匀性、基底地形的空间格局、沉积物厚度和沉积物内的裂谷不整合面以及地壳和岩石圈内的特征（例如，断层和地壳厚度变化）。需要对这些特征进行MCS成像，以评估后期裂谷过程以及这些过程的时间和空间变化。不同的运动学板块模型的最早阶段的中大西洋的演变作出了非常不同的预测的半扩展率。此外，现代中大西洋海脊的大规模分段也被认为是继承了邻近大陆边的几何形状。来自该项目的MCS数据将限制基底粗糙度、地壳厚度和地壳结构以及沿着和横跨新洋壳的反射率的变化，这将对早期海底扩张历史提供重要的限制，并将有助于区分相互竞争的模型。