Along-strike variations in synrift magmatism on the Eastern North American Margin

北美东部边缘同裂谷岩浆作用的沿走向变化

• 批准号: 1654629
• 负责人: Donna Shillington
• 金额: $ 13.17万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-04-15 至 2021-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1654629&HistoricalAwards=false
• 关键词: Along; strike; variations; synrift; magmatism

Continental breakup to form new oceans is often accompanied by extensive outpouring of magmatism. Magmas may make continental breakup possibly by heating up and weakening continental tectonic plates. Volcanism associated with these events has also been associated with major extinction events on Earth. Despite the importance of magmatism during continental breakup, very little is known about the total volume of magmatism involved during rifting and how the volume varies between rift systems. The continental margin off the coast of the eastern U.S. is one of the best examples in the world of a continental breakup event associated with extensive magmatism. One of the biggest magmatic events in history occurred during the breakup of the supercontinent of Pangea and opening of the Atlantic Ocean. This project will involve the analysis of existing marine seismic data collected across the margin offshore North Carolina in 2014 to quantify the volume and distribution of magma frozen in the crust and how it relates to the structures that allowed breakup to occur. The project supports the training of an undergraduate student.Magmatic intrusions contribute to the growth and modification of the crust of the Earth and strongly influence strain localization in a variety of tectonic settings. Despite this, very few constraints exist on the 3-D distribution of magmatic intrusions throughout the crust in a tectonic setting that can be used to understand the controls on their distribution and the consequences for crustal modification and deformation. This project focuses on magmatism in rifts, but the scientific questions apply across many tectonic settings. Do intrusions exploit pre-existing structures and/or are they focused in the areas of greatest crustal/lithospheric thinning? Does the volume of intrusions in magmatic rifts vary along strike and relate to segmentation at the mid-ocean ridge, or does voluminous magmatism overwhelm focusing mechanisms and result in a more uniform distribution of intrusions along the margin? A 3D seismic velocity model of the crust and uppermost mantle will be built in one of the type examples of magma-rich continental rifting: The Eastern North American Margin (ENAM). The NSF-GeoPRISMS Program supported the collection of active/passive, onshore/offshore seismic data across the ENAM in 2014. As a part of this experiment, data were also collected along and across the East Coast Magnetic Anomaly, which is thought to mark the location of significant synrift magmatism. The data provide excellent 3-D ray coverage of the ENAM area and will be used for 3-D travel time tomography. The resulting velocity model will be used to map the 3-D distribution of magmatic intrusions. This part of the margin is an excellent place to test competing ideas for controls on synrift magmatic addition to the crust.

大陆分解以形成新的海洋，通常伴随着大量的岩浆主义。 岩浆可能会通过加热和削弱大陆构造板来使大陆分解。与这些事件相关的火山主义也与地球上的重大灭绝事件有关。尽管在大陆分解过程中岩浆主义的重要性很重要，但对于裂谷过程中涉及的岩浆总数以及裂谷系统之间的体积如何变化，知之甚少。美国东部沿海的大陆边缘是世界上与广泛岩浆作用相关的大陆分手事件的世界上最好的例子之一。历史上最大的岩浆事件之一是在庞吉亚超大型企业的分手和大西洋开放期间。 该项目将涉及对2014年在北卡罗来纳州近海边缘收集的现有海洋地震数据的分析，以量化冰冻中冰冻的岩浆的体积和分布及其与允许分裂发生的结构的关系。该项目支持对本科生的训练。魔力侵入有助于地球地壳的生长和修改，并在各种构造环境中强烈影响应变定位。 尽管如此，在整个地壳的3-D分布中，在构造环境中的3-D分布中存在很少的约束，该构造环境可用于了解其分布的控制以及对地壳修饰和变形的后果。 该项目的重点是裂谷中的岩浆性，但是科学问题适用于许多构造环境。入侵是否会利用预先存在的结构和/或它们集中在最大的地壳/岩石圈稀疏区域？岩浆裂缝中的入侵量是否随着罢工而变化，并且与中山脊的分割有关，还是大量的岩浆岩浆层压着焦点的机制，导致沿边缘的入侵分布更加均匀？地壳和最高地幔的3D地震速度模型将建立在岩浆丰富的大陆裂谷的类型之一中：东北美边缘（ENAM）。 NSF-Geprisms计划支持收集2014年ENAM的主动/被动，陆上/离岸地震数据。作为本实验的一部分，还沿着东海岸磁异常收集了数据，这被认为标志着明显的同步岩浆质量的位置。 数据提供了ENAM区域的出色3-D射线覆盖范围，并将用于3D旅行时间断层扫描。所得的速度模型将用于绘制岩浆入侵的3-D分布。边距的这一部分是测试与地壳中岩浆岩浆岩浆的控制互动想法的绝佳场所。