Results 31 to 40 of about 121 (99)

Ultra‐Low Velocity Zone Beneath the Atlantic Near St. Helena

Geochemistry, Geophysics, Geosystems
There are various hotspots in the Atlantic Ocean, which are underlain by mantle plumes that likely cross the mantle and originate at the core‐mantle boundary. We use teleseismic core‐diffracted shear waves to look for an Ultra‐Low Velocity Zone (ULVZ) at
Sefira Davison, Carl Martin, Rita Parai, Sanne Cottaar   +3 more
doaj   +1 more source

A new probe of ULVZ S‐wave velocity structure: Array stacking of ScS waveforms

Geophysical Research Letters, 2006
S‐wave velocity reductions in thin layers above the core‐mantle boundary (CMB) are resolved by modeling precursors to the tangential‐components of core‐reflected ScS phases. Unlike most phases used to study ultra‐low velocity zone (ULVZ) structure, ScS provides direct sensitivity to shear velocity structure, VS.
Megan Avants, Thorne Lay, Edward J. Garnero   +2 more
openaire   +1 more source

Regimes of Element Transfer Between Earth's Core and Basal Magma Ocean

Journal of Geophysical Research: Solid Earth, Volume 130, Issue 7, July 2025.
Abstract Earth's accretion was highly energetic and likely involved multiple global melting events. Following the Moon‐forming giant impact, extensive mantle melting and the separation of solids and melts under deep mantle pressures likely produced a basal magma ocean (BMO) beneath the solidified mantle.
Zhongtian Zhang, Haiyang Luo, Ming Hao, Jie Deng   +3 more
wiley   +1 more source

The Hole in the Pacific LLVP and Multipathed SKS

Geosciences
In contrast to a relatively simple whole structure of the African Large Low Velocity Province (LLVP), the Mid-Pacific LLVP appears to be much more complex and likely interacts more with the down-going slab debris from the circum-Pacific subduction zones.
Daoyuan Sun
doaj   +1 more source

Small post‐perovskite patches at the base of lower mantle primordial reservoirs: Insights from 2‐D numerical modeling and implications for ULVZs

Geophysical Research Letters, 2016
AbstractWe perform numerical experiments of thermochemical mantle convection in 2‐D spherical annulus geometry to investigate the distribution of post‐perovskite (pPv) with respect to the location of primordial reservoirs of dense material in the lowermost mantle.
Li, Yang, Deschamps, Frédéric, Tackley, Paul J.   +2 more
openaire   +2 more sources

Thermal Evolution of Planetary Interiors With a Crystallizing Basal Magma Ocean Coupled to Parameterized Mantle Convection

Journal of Geophysical Research: Planets, Volume 130, Issue 7, July 2025.
Abstract Basal magma oceans (BMOs) persisting in the silicate portion of terrestrial planets for long periods of time (> ${ >} $1 Gyr) offer the potential to reconcile unexplained contradictions between geochemical and geophysical observations, yet our knowledge of how the presence of such layers influence planetary evolution is far from mature.
Victoria Auerbach, Dave R. Stegman
wiley   +1 more source

Detection of Lowermost Mantle Heterogeneity Using Seismic Migration of Diffracted S‐Waves

Journal of Geophysical Research: Solid Earth, Volume 130, Issue 6, June 2025.
Abstract The bottom of Earth's mantle hosts strong seismic wave speed heterogeneities. These are commonly detected via forward modeling of seismic waveforms, which can include time‐consuming waveform synthesis and visual inspection. Furthermore, such imaging has been most commonly carried out with waves that have limited global coverage.
Jonathan Wolf, Edward Garnero, Benjamin Schwarz, Kuangdai Leng, Yantao Luo, Regina Maass, John D. West   +6 more
wiley   +1 more source

Ab Initio Study of the Conductivities of B2 FeSi Under Core‐Mantle Boundary Conditions

Geophysical Research Letters, Volume 52, Issue 10, 28 May 2025.
Abstract While the ultra‐low velocity zones (ULVZs) may hold key information about deep Earth dynamics, their elusive state and origin remain enigmatic. Recent high‐pressure experiments suggest that ULVZs may originate from the B2 FeSi crystallization from the outer core. Understanding the conductivity of the B2 phase can shed light on its role in deep
Yonghui Huang, Yunguo Li, Dario Alfè, Monica Pozzo, Huaiwei Ni   +4 more
wiley   +1 more source

Evidence for Ultra-Low Velocity Zone Genesis in Downwelling Subducted Slabs at the Core–Mantle Boundary

The Seismic Record
We investigate broadband SPdKS waveforms from earthquakes occurring beneath Myanmar. These paths sample the core–mantle boundary beneath northwestern China.
Madeleine M. Festin, Michael S. Thorne, Mingming Li   +2 more
doaj   +1 more source

A melting model for the lowermost mantle using Clapeyron slopes derived from experimental data: Consequences for the thickness of ultralow velocity zones (ULVZs)

Geochemistry, Geophysics, Geosystems, 2013
Ultralow velocity zones (ULVZs) are relatively thin regions directly above the core‐mantle boundary (CMB) that exhibit marked seismic P‐ and S‐velocity reductions. A viable explanation for the reduction is the presence of melt fractions within ULVZs.
Marcus J. Beuchert, Harro Schmeling
openaire   +1 more source