Mantle Layer: Composition, Structure, and Dynamics
The Earth’s mantle is a layer of solid rock extending from the core-mantle boundary (CMB) to the lithosphere. It is the largest and most important layer of the Earth, and is composed primarily of silicate minerals, such as olivine, pyroxene, and garnet. This layer is also where most of the Earth’s seismic activity occurs. The mantle is divided into two distinct parts: the upper mantle and the lower mantle. The upper mantle, which extends from the CMB to the 660-kilometer discontinuity, is composed of softer, more easily deformed rocks. The lower mantle, which extends from the 660-kilometer discontinuity to the Mohorovicic discontinuity, is composed of denser, more rigid rocks.
The mantle is a dynamic layer, and is constantly in motion. It is broken into several layers, each with its own composition and structure. The uppermost layers of the mantle contain a mixture of silicate minerals, while the lower layers are composed of more dense minerals, such as periclase and bridgmanite. The mantle convects heat from the core to the surface through a process known as mantle convection. This process is responsible for the movement of tectonic plates and the formation of volcanoes and mountain ranges.
The mantle is also important for the formation of mineral deposits. As minerals are heated and pressurized within the mantle, they become more chemically stable and form deposits of precious metals and gems. This process, known as metamorphism, is responsible for the formation of many of the Earth’s major mineral deposits.
The mantle is a complex and dynamic layer, and much is still unknown about its composition, structure, and dynamics. However, advances in seismology, geochemistry, and other fields of Earth sciences are helping to shed light on these mysteries. By studying the mantle, we can gain a better understanding of the Earth’s structure and how it has evolved over time.
References
American Geosciences Institute. (2017). Earth’s Mantle: Composition, Structure, and Dynamics. Retrieved from https://www.americangeosciences.org/education/k5geosource/earth-structure/earths-mantle-composition-structure-and-dynamics
Bercovici, D., & Ricard, Y. (2012). Mantle Dynamics. In Treatise on Geophysics (2nd ed., pp. 573-608). Amsterdam: Elsevier.
Gurnis, M., & Tackley, P. J. (2008). Mantle Convection. In Encyclopedia of Geology (pp. 441-454). Oxford: Elsevier.
Karpoff, A. M., & Turcotte, D. L. (2005). Metamorphism. In Encyclopedia of Geology (pp. 677-685). Oxford: Elsevier.