Aluminum- and Iron-rich Perovskites and Post-perovskites and Earth's Deep Lower Mantle

富含铝和铁的钙钛矿和后钙钛矿以及地球深层下地幔

• 批准号: 0838017
• 负责人: Thomas Duffy
• 金额: $ 25.18万
• 依托单位: Princeton University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-02-01 至 2013-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0838017&HistoricalAwards=false
• 关键词: Aluminum; Iron; rich; Perovskites; Post

Understanding the deep interior of the Earth is a key ingredient in unraveling the processes involved in the origin and evolution of our planet. In addition, the geological activity that manifests itself so profoundly at the surface of the Earth has its ultimate origins in processes ongoing in the deep interior. Studying minerals under the extreme pressure-temperature conditions of the deepest Earth provides a means to test the limits of our understanding of basic physical and chemical properties of materials. The Earth's core-mantle boundary is particularly complex as it juxtaposes the churning liquid iron core against the hot but solid silicate minerals of the deep mantle at greater than a million times atmospheric pressure. In this work, we propose to recreate the conditions of Earth's deep mantle in the laboratory and study the detailed nature of the crystal structures that form under such conditions and their physical properties.The Earth's core-mantle boundary region (called D") is a thin layer (~200 km thick) lying just above the core that has long been of interest due to its unusual seismic properties. Perovskites (Pv) and post perovskites (pPv) are expected to be the major mineral phases of Earth's lower mantle and core-mantle boundary regions. Seismic evidence indicates the deep lower mantle exhibits considerable chemical heterogeneity and this may result from such phenomena as core-mantle interactions, partial melting in D", retained primordial material, or accumulation of subducting slabs. This chemical complexity will influence many key properties of the deep mantle including location and width of phase boundaries, density, sound velocities, element partitioning, and transport and thermal properties. In this project, the investigators will use synchrotron x-ray diffraction and scattering techniques to explore the behavior of iron- and aluminum-bearing perovskites and post-perovskites over a wide pressure range. They will synthesize a variety of phases at conditions up to 200 GPa and 2500 K and measure such properties as equations of state, compressibilities, phase boundaries, and Clapeyron slopes. This study of chemically complex systems at high pressures and temperatures will enable a better interpretation of seismically observed deep mantle structure in terms of the physical and chemical properties of realistic mineral assemblages. The proposed research will yield advances in understanding the geochemistry and thermoelastic properties of minerals of relevance for the Earth's deep mantle, and will impact the fields of mineral physics, geodynamics, seismology, and petrology.

了解地球的深层内部是揭示地球起源和演化过程的关键因素。 此外，在地球表面如此深刻地表现出来的地质活动，其最终起源是在地球内部深处正在进行的过程。 在地球最深处的极端压力-温度条件下研究矿物提供了一种方法来测试我们对材料基本物理和化学性质的理解的极限。 地球的地核-地幔边界特别复杂，因为它将搅动的液态铁核与深部地幔炽热但固态的硅酸盐矿物并置，压力超过一百万倍大气压。 在这项工作中，我们建议在实验室中重现地球深部地幔的条件，并研究在这种条件下形成的晶体结构的详细性质及其物理性质。地球的核心-地幔边界区域（称为 D"）是位于核心正上方的一个薄层（约 200 公里厚），由于其不寻常的地震特性，长期以来一直受到人们的关注。预计会出现钙钛矿 (Pv) 和后钙钛矿 (pPv) 是地球下地幔和核-地幔边界区域的主要矿物相。 地震证据表明，深部下地幔表现出相当大的化学异质性，这可能是由于核心-地幔相互作用、D"部分熔融、保留的原始物质或俯冲板片的堆积等现象造成的。 这种化学复杂性将影响深部地幔的许多关键特性，包括相界的位置和宽度、密度、声速、元素分配以及传输和热特性。 在这个项目中，研究人员将使用同步加速器X射线衍射和散射技术来探索含铁和铝的钙钛矿和后钙钛矿在宽压力范围内的行为。 他们将在高达 200 GPa 和 2500 K 的条件下合成各种相，并测量状态方程、压缩性、相界和克拉佩龙斜率等特性。 这项对高压和高温下化学复杂系统的研究将能够根据真实矿物组合的物理和化学性质更好地解释地震观测到的深层地幔结构。 拟议的研究将在了解与地球深层地幔相关的矿物的地球化学和热弹性特性方面取得进展，并将影响矿物物理学、地球动力学、地震学和岩石学领域。