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

大陆裂解形成新的海洋往往伴随着大量的岩浆活动。岩浆可能通过加热和削弱大陆构造板块而使大陆解体。与这些事件相关的火山作用也与地球上的重大物种灭绝事件有关。尽管岩浆作用在大陆解体过程中很重要，但人们对裂谷过程中涉及的岩浆活动总量以及不同裂谷系统之间的体积变化知之甚少。美国东部沿海的大陆边缘是世界上与广泛的岩浆作用有关的大陆分裂事件的最好例子之一。历史上最大的岩浆事件之一发生在盘古大陆解体和大西洋开放期间。该项目将涉及对2014年在北卡罗来纳州近海边缘地区收集的现有海洋地震数据进行分析，以量化冻结在地壳中的岩浆的数量和分布，以及它与允许发生破裂的构造之间的关系。该项目支持对本科生的培训。岩浆侵入作用有助于地壳的生长和改造，并强烈影响各种构造环境中的应变局部化。尽管如此，在可以用来了解岩浆侵入体分布的控制以及地壳变形和变形后果的构造背景下，对岩浆侵入体在整个地壳中的三维分布几乎没有什么限制。这个项目的重点是裂谷中的岩浆作用，但这些科学问题适用于许多构造背景。侵入体是否利用先前存在的构造和/或它们集中在地壳/岩石圈减薄最严重的地区？岩浆裂谷中侵入体的体积是否沿走向变化并与大洋中脊的分段有关，还是巨大的岩浆作用压倒了聚焦机制，导致侵入体沿边缘分布更均匀？在富含岩浆的大陆裂谷作用的典型例子之一：北美东部边缘(ENAM)，将建立地壳和最上地幔的三维地震速度模型。2014年，NSF-GeoPRISMS方案支持在整个ENAM地区收集主动/被动、陆上/近海地震数据。作为这项实验的一部分，还收集了东海岸磁异常的数据，该异常被认为标志着重大同裂谷岩浆活动的位置。这些数据提供了埃纳姆地区出色的3-D射线覆盖率，并将用于3-D旅行时间断层成像。得到的速度模型将被用来绘制岩浆侵入的三维分布图。边缘的这一部分是检验控制同裂谷岩浆添加到地壳的相互竞争的好地方。

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.