Asthenospheric melting and melt-induced evolution of the lithosphere beneath the Colorado Plateau and the Basin and Range from a seismic characterization of mantle layering

地球上地幔的部分熔融在控制地表火山活动方面起着关键作用。它还影响构造板块的演化和下面的热地幔的变形，称为软流圈。近年来，美国大陆已经被EarthScope的可移动阵列覆盖，该计划部署了数千台地震仪器。收集到的数据提供了前所未有的最上层地幔结构的新约束，告知其动力学和历史的形成和改变。在这里，研究人员分析了来自科罗拉多高原的数据，这是一个具有古老的元古代地壳的地区。该地区在多次挤压事件和随后周围盆地和山脉的延伸中保持相对未变形。高原从接近海平面上升到目前的高度还没有很好的理解。盆地和山脉的火山活动现在正在积极地侵蚀古老的高原。 通过结合地震学和热力学模型，研究小组绘制出了最上层地幔的部分熔融和蚀变。 该项目为美国西南部一个重要地区的过去演变和现状带来了新的曙光。它还支持一名早期职业女性科学家，首席研究员，并为地震学领域的本科生提供培训。该团队调查了科罗拉多高原地区，在那里，不同的构造环境在一个小的地理区域内并列。研究人员使用面波频散数据和来自S-to-P接收器函数的关于上地幔急剧速度梯度的信息。他们计算精确的地震速度模型，采用地质合理的分层框架。该模型建立在首席研究员以前的工作与接收器功能，它提供了分层的岩石圈软流层框架，其中反演的分散数据。该团队将联合收割机地震分析与热力学建模以自洽的方式结合起来，以估计区域速度结构。该模型考虑了组分、压力和温度以及深度处的熔体分数。这些估计受到该地区丰富的火山活动和捕虏体的成分和温度数据的限制。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Partial melting in the Earth's upper mantle plays a key role in controlling surface volcanism. It also impacts the evolution of tectonic plates and the deformation of the hot mantle underneath, called the asthenosphere. In recent years, the continental United States has been blanketed by EarthScope's Transportable Array, a program that deployed thousands of seismic instruments. The collected data provide unprecedented new constraints on the structure of the uppermost mantle, informing its dynamics and history of formation and alteration. Here, the researchers analyze the data from the Colorado Plateau, an area with ancient Proterozoic crust. This area has remained relatively undeformed through multiple compression episodes and subsequent extension of the surrounding Basin and Range. The rise of the Plateau from near sea level to its current elevation is not well understood. The volcanism of the Basin and Range is now actively encroaching on the ancient Plateau. By combining seismology and thermodynamic modeling, the team maps out the partial melt and alteration of the uppermost mantle. This project brings new light on the past evolution and present state of an important region of the southwestern United States. It also supports an early-career female scientist, the principal investigator, and provides training to an undergraduate student in the field of seismology.The team investigates the Colorado Plateau region, where disparate tectonic settings are juxtaposed within a small geographical area. The researchers use surface-wave dispersion data and information derived from S-to-P receiver functions about sharp velocity gradients in the upper mantle. They calculate accurate seismic-velocity models which employ a geologically reasonable layered framework. The models build on the Principal Investigator's previous work with receiver functions, which provides the layered lithosphere-asthenosphere framework in which to invert the dispersion data. The team combine seismic analysis with thermodynamic modeling in a self-consistent way to estimate regional velocity structures. The modeling accounts for the composition, pressure and temperature, as well as melt fraction at depth. These estimates are constrained by compositional and temperature data from the abundant volcanism and xenoliths in the area.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.