Results 31 to 40 of about 3,352 (155)

The Gravity Signal of Mercury's Inner Core

Earth and Space Science, 2022
In a reference frame rotating with Mercury's mantle and crust, the inner core and fluid core precess in a retrograde sense with a period of 58.646 days.
Mathieu Dumberry
doaj   +1 more source

Upwellings and Mantle Ponding Zones in the Lower Mantle Transition Zone (660–1000 km)

Geosciences
Convective instabilities at various boundary layers in the earth’s mantle—including the core–mantle boundary, mantle transition zone and lithosphere-asthenosphere boundary— result in upwellings (mantle plumes) and downwellings (subducting slabs).
Jean-Paul Montagner, Barbara Romanowicz, Mathurin Wamba, Gael Burgos   +3 more
doaj   +1 more source

Grain boundary diffusion cannot explain the W isotope heterogeneities of the deep mantle

Nature Communications
The low 182W/184W and high 3He/4He in some ocean island basalts compared to the bulk mantle values may derive from the Earth’s core through long-term core-mantle interactions. It has been proposed that the grain boundary diffusion of siderophile elements
Yihang Peng, Takashi Yoshino, Jie Deng
doaj   +1 more source

Enhanced Core-Mantle Coupling Due to Stratification at the Top of the Core

Frontiers in Earth Science, 2018
Fluctuations in the length of day (LOD) over periods of several decades are commonly attributed to exchanges of angular momentum between the mantle and the core. However, the forces that enable this exchange are less certain.
Sebastian Glane, Bruce Buffett
doaj   +1 more source

An Ancient Martian Dynamo Driven by Hemispheric Heating: Effect of Thermal Boundary Conditions

The Planetary Science Journal, 2023
Magnetic field observations from the MGS, MAVEN, and InSight missions reveal that a dynamo was active in Mars’s early history. One unique feature of Mars’s magnetic crustal field is its hemispheric dichotomy, where magnetic fields in the southern ...
Chi Yan, Ankit Barik, Sabine Stanley, Jason S.-Y. Leung, Anna Mittelholz, Catherine L. Johnson, Ana-Catalina Plesa, Attilio Rivoldini   +7 more
doaj   +1 more source

HYDROGEN IN THE EARTH’S OUTER CORE, AND ITS ROLE IN THE DEEP EARTH GEODYNAMICS

Геодинамика и тектонофизика, 2016
The content of hydrogen in the outer core of the Earth is roughly quantified from the dependence of the density of iron (viewed as the main component of the core) on the amount of hydrogen dissolved in the core, with account of the most likely presence ...
V. N. Rumyantsev
doaj   +1 more source

Rolling hills on the core–mantle boundary

Earth and Planetary Science Letters, 2013
Recent results suggest that an iron-rich oxide may have fractionally crystallized from a primordial magma ocean and settled on the core–mantle boundary (CMB). Based on experimental results, the presence of only a few percent of Fe-rich oxide could slow seismic waves down by several percent.
Sun, Daoyuan, Helmberger, Don V., Jackson, Jennifer M., Clayton, Robert W., Bower, Dan J.   +4 more
openaire   +2 more sources

Topography at the core‐mantle boundary

Geophysical Research Letters, 1986
Analysis of the Earth's gravity field using ratio of gravity to geoid (g/N) and cumulative degree contribution curve techniques improves resolution of the mass, depth, and dimensions of anomalous mass sources within the planet. The source for four of the ten major geoid anomalies of the Earth has large contributions from harmonic degrees 2 and 3, lie ...
openaire   +1 more source

Hot action at the core‐mantle boundary

Eos, Transactions American Geophysical Union, 1994
Recent discoveries about the Earth's most prominent internal feature, the core‐mantle boundary, were revealed at a workshop just held at the University of California at Berkeley. The latest seismological evidence points to the interface between the mantle and core being among the most dynamically active regions of the planetary interior.Though distant,
Raymond Jeanloz, Barbara Romanowicz
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Dissipation at the core‐mantle boundary on a small‐scale topography [PDF]

Journal of Geophysical Research: Solid Earth, 2006
The parameters of the nutations are now known with a good accuracy, and the theory accounts for most of their values. Dissipative friction at the core‐mantle boundary (CMB) and at the inner core boundary is an important ingredient of the theory. Up to now, viscous coupling at a smooth interface and electromagnetic coupling have been considered. In some
Le Mouël, Jean-Louis, Narteau, C, Greff-Lefftz, M, Holschneider, M   +3 more
openaire   +4 more sources