C and H Retention Mechanisms in the Deep Earth

碳和水在地球岩石内部和表面之间的循环对海洋和大气的形成和长期演化至关重要。它影响了地球固体地幔的组成、融化和粘性流动。大陆的形成，大多数火山活动的产生，以及可能的板块构造本身，都取决于碳和水（或其组成元素氢）在地球内部储存和从内部释放的方式。然而，在地幔条件下测量C和H的化学性质是具有挑战性的，因为在深处存在极端的压力和温度。在这里，研究人员通过实验研究了碳和氢是如何储存在地幔中存在的矿物质中的。他们还测试了这些矿物质持续存在或释放这些元素的条件。该团队开发并使用了最先进的高压设备来重现地幔的极端条件。在实验中，他们探索了C和H在不同压力和温度下在宿主矿物中的行为方式。他们的工具是在一个国家同步加速器设施中使用强大的x射线，在他们的家庭实验室中使用红外线和激光。该项目还为加州大学圣克鲁斯分校的研究生和本科生提供支持和培训。它是由NSF地球物理项目和岩石地球化学项目共同资助的。该团队在室温和高温下，在钻石砧细胞中进行单晶x射线衍射和振动光谱测量（红外和拉曼），在两个对立钻石的尖端产生极端压力。研究人员研究了一系列的碳酸和水合相，以研究挥发性物质在地球上的保留和循环。探索了与地球不稳定的预算和不相容元素的隔离相关的阶段。具体而言，该项目旨在：(1)表征压缩下目标相碳酸盐单元的移位键合环境-该单元可能在高压下发生异常键合变化；(2)以前所未有的分辨率探测了稳定场最接近上地幔中深部条件的水合相高压结构。该团队还继续增强和测试位于劳伦斯伯克利国家实验室先进光源的社区可访问的高压/高温单晶x射线衍射设备的能力。该奖项反映了美国国家科学基金会的法定使命，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。

The cycling of carbon and water between the Earth’s rocky interior and its surface is critical for the genesis and long-term evolution of oceans and atmosphere. It influences the composition, melting, and viscous flow of the planet’s solid mantle. The genesis of continents, the production of most volcanism, and likely plate tectonics itself hinge on the way carbon and water (or its constituent hydrogen) are stored within the Earth and released from its interior. Yet, measuring C and H chemical properties at mantle conditions is challenging, because of the extreme pressures and temperatures prevailing at depth. Here, the researchers investigate experimentally how C and H are stored within the minerals present in the mantle. They also test the conditions in which these minerals persist or release these elements. The team develops and uses state-of-the-art high-pressure devices to reproduce the mantle’s extreme conditions. During the experiments, they explore the way C and H behave in their host minerals at various pressures and temperatures. Their tools are powerful X-rays at a national synchrotron facility, and infrared and laser light in their home laboratory. The project also provides support and training for graduate and undergraduate students at the University of California Santa Cruz. It is co-funded by the NSF Geophysics program and Petrology and Geochemistry program.The team conducts single-crystal X-ray diffraction and vibrational spectroscopic measurements (Infrared and Raman) at room and high temperature in the diamond anvil cell, where extreme pressures are produced at the tips of two opposing diamonds. The researchers investigate a sequence of carbonated and hydrated phases of interest for volatile retention and cycling within Earth. Phases that are relevant for both the planet’s volatile budget and the sequestration of incompatible elements are probed. Specifically, the project aims to: (1) characterize the shifting bonding environment of the carbonate unit in targeted phases under compression - a unit that may undergo anomalous bonding changes at high pressures; and (2) probe at an unprecedent resolution the high-pressure structure of the hydrated phase whose stability field most closely approaches the conditions of the mid- to deep-upper mantle. The team also continues to augment and test the capabilities of a community-accessible, high-pressure/high-temperature single crystal X-ray diffraction facility located at the Advanced Light Source at Lawrence Berkeley National Labs.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.