在核心-地幔边界的可能羽毛根的地震约束
Sebastian Rost1, Edward J Garnero, Quentin Williams
1Department of Geological Sciences, Arizona State University, Box 871404, Tempe , Arizona 85287-1404, USA. srost@asu.edu
Nature
|June 3, 2005
概括
地震波分析显示,在澳大利亚东部的地球核心-地幔边界处有一个密集的,部分化的口袋. 这种复杂的结构,与纯融不同,表明被困的晶体,可能表明深层羽毛根区域.
科学领域:
- 地质物理学 地质物理学
- 地震学 地震学
- 地球科学 地球科学 地球科学
背景情况:
- 地球的核心-地幔边界表现出复杂的结构,而不是简单的接口.
- 地震波速度的减速表明,地幔最下层存在局部复杂性.
研究的目的:
- 证明在核心-地幔边界处有一个特定的,密集的,部分化的物质口袋.
- 描述这种异常的地震特性和影响.
主要方法:
- 对异常地震波 (ScP) 前体的阵列分析.
- 计算压缩和剪切波速度和密度变化.
主要成果:
- 在澳大利亚东部发现了一个8.5公里厚,50公里宽的密,部分化的物质口袋.
- 观察到地震速度减少 (8%的压缩,25%的剪切) 和10%的密度增加.
- 地震数据表明,非纯融的组成需要融捕获机制.
结论:
- 这种异常很可能是由被困的融形成的累积结构,可能来自覆盖的热区域.
- 这种结构可能代表上升的地幔羽毛的根区.
- 这些发现凸显了核心-地幔界限的复杂性质.
相关概念视频
Elastic Collisions: Case Study
Elastic collision of a system demands conservation of both momentum and kinetic energy. To solve problems involving one-dimensional elastic collisions between two objects, the equations for conservation of momentum and conservation of internal kinetic energy can be used. For the two objects, the sum of momentum before the collision equals the total momentum after the collision. An elastic collision conserves internal kinetic energy, and so the sum of kinetic energies before the collision equals...
Strain and Elastic Modulus
The quantity that describes the deformation of a body under stress is known as strain. Strain is given as a fractional change in either length, volume, or geometry under tensile, volume (also known as bulk), or shear stress, respectively, and is a dimensionless quantity. The strain experienced by a body under tensile or compressive stress is called tensile or compressive strain, respectively. In contrast, the strain experienced under bulk stress and shear stress is known as volume and shear...
Elastin is Responsible for Tissue Elasticity
Elastic fiber contains the protein elastin along with lesser amounts of other proteins and glycoproteins. The main property of elastin is that it will return to its original shape after being stretched or compressed. Elastic fibers are prominent in elastic tissues found in skin and the elastic ligaments of the vertebral column.
Ligaments and tendons are made of dense regular connective tissue, but in ligaments not all fibers are parallel. Dense regular elastic tissue contains elastin fibers and...
Ligaments and tendons are made of dense regular connective tissue, but in ligaments not all fibers are parallel. Dense regular elastic tissue contains elastin fibers and...
Elastic Strain Energy for Normal Stresses
Strain energy quantifies the energy stored within a material due to deformation under loading conditions, a fundamental concept in materials science and engineering. The strain energy can be modeled when a material is subjected to axial loading with uniformly distributed stress. In this scenario, the stress experienced by the material is the internal force divided by the cross-sectional area, and the strain induced is directly proportional to this stress through the modulus of elasticity.
If...
If...
Elastic Strain Energy for Shearing Stresses
As discussed in previous lessons, strain energy in a material is the energy stored when it is elastically deformed, a concept crucial in materials science and mechanical engineering. This energy results from the internal work done against the cohesive forces within the material. When a material undergoes shearing stress and corresponding shearing strain, the strain energy density, which is the energy stored per unit volume, is calculated. Within the elastic limit, where the stress is...
Elasticity in Concrete
Upon subjecting concrete to moderate or high uniaxial compressive or tensile stresses, the strain response is non-linear relative to the stress applied. As the stress is removed, the resulting stress-strain curve deviates from the original path traced during loading, creating a hysteresis loop, indicative of the concrete's non-linear and non-elastic properties. Typically, a material's modulus of elasticity, which is a measure of the material's stiffness, is inferred from the linear portion of...


